bluuebunny/crossref_metadata_2025 huggingface dataset:
Bleomycin‐induced urticarial flagellate drug hypersensitivity reaction
Authors: Rubeiz Nelly G.. , Salem Ziad , Dibbs Rania , Kibbi Abdul‐Ghani
Published: March 2003

New York, NY 10022[TAB]A 70‐year‐old woman was found to have an infiltrating ductal carcinoma of the right breast in July 1992, for which she underwent a modified radical mastectomy and was started on tamoxifen. In May 1995, she presented with metastasis to the right lung and ribs. The patient received 60 mg of bleomycin intrapleurally, and was started on leucovorin, 5‐fluorouracil and mitoxantrone. One week following the administration of chemotherapy, she developed pruritic erythematous indurated dermal papules and plaques, arranged in a linear configuration over the face, trunk and extremities ( Fig. 1). The patient is right‐handed. Two skin biopsy specimens, obtained from the forehead and right anterior chest, exhibited similar histopathologic features. Beneath focal areas of parakeratosis, the dermis displayed papillary dermal edema and superficial and deep perivascular and interstitial mixed inflammatory cell infiltrate composed of lymphocytes, neutrophils and eosinophils (Fig. 2). These findings were consistent with an urticarial allergic drug hypersensitivity reaction. The eruption resolved over a period of 1 month leaving residual linear and flagellate hyperpigmentation.

Flagellate erythema over the back

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Perivascular and interstitial mixed inflammatory cell infiltrate(× magnification)[TAB]

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Squamous cell carcinoma and keratoacanthoma of the lower lip associated with “Goza” and “Shisha” smoking
Authors: El‐Hakim Ibrahim E. , Uthman Mirghani A.E.
Published: March 2003

Background A positive correlation between lip and buccal cancers and pipe smoking has been suggested. Various types of crude and manufactured tobacco products are consumed by smoking, chewing, and snuff dipping habits. “Shisha” and “Goza” smoking are widely practiced in the Middle East. The “hubble‐bubble” method and apparatus are used. These smoking habits are hazardous to health, causing obstructive lung disease, and may be important predisposing factors for the development of oral cancers.

Case reports Two cases of squamous cell carcinoma and a case of keratoacanthoma localized to the lower lip are presented in well‐known “Shisha” and “Goza” smokers.

Conclusions“Shisha” and “Goza” smoking have adverse effects on general health and may predispose to oral cancer. An extensive epidemiological study should be performed to determine whether this type of smoking habit is associated with a statistically increased incidence of squamous cell carcinoma and keratoacanthoma of the lips.
Pemphigus and pemphigoid‐like effects of nifedipine on in vitro cultured normal human skin explants
Authors: Brenner Sarah , Ruocco Vincenzo , Bialy‐Golan Anat , Tur Ethel , Flaminio Concetta , Ruocco Eleonora , Lombardi Maria Luisa
Published: March 2003

Background A variety of drugs have been implicated in the onset and exacerbation of pemphigus and bullous pemphigoid. The demonstration of biochemical acantholysis in skin explants to various drugs in the absence of autoantibodies, in which the tested drugs evoke a biochemical reaction that leads to desmosomal function loss, may be a valuable adjunct to patient management by confirming the suspicion of drug‐related pemphigus or bullous pemphigoid.

Objective To determine whether a skin explant model might serve as a possible in vitro correlate of drug‐induced pemphigus and pemphigoid‐like effects related to the calcium channel blocker nifedipine.

Methods Normal human breast skin obtained from nonpemphigus and nonpemphigoid patients undergoing mastectomy was cultured with nifedipine at final concentrations of 2, 4, and 8 mm. The drug effect on skin explants evidenced by morphologic changes was evaluated by microscopy by three observers.

Results Five out of seven explants cultured with nifedipine at concentrations ranging from 2 to 8 mm exhibited obvious morphologic changes of two types: intraepithelial (or pemphigus‐type) splittings and subepithelial (or pemphigoid‐type) splittings. Two explants showed no acantholysis and no subepithelial splittings. Control cultures without polyethylene glycol 200 (PEG) showed no changes. Skin control samples cultured in medium supplemented with 10% PEG displayed vacuolar degeneration throughout the entire epidermis, but no sign of cell–cell dyshesion or dermo‐epidermal detachment.

Conclusions A type of skin susceptibility to nifedipine may be genetically determined, with some nifedipine‐treated patients developing an acantholytic reaction and others a subepidermal bullous eruption.
Modified technique of suction blistering for epidermal grafting in vitiligo
Authors: Gupta Somesh , Shroff Satish , Gupta Sanjeev
Published: March 2003

Background Suction blister epidermal grafting is a useful modality of treatment of resistant and stable vitiligo; however, it requires expensive and heavy suction apparatus. This study is an attempt to develop a cheap and small apparatus which can be assembled in the physician’s own office.

Patients and methods The method was tried in 22 vitiligo/leukoderma patients. The apparatus consisted of a cylindrical funnel connected with a three‐way tap , and suction was given by a 50‐mL syringe. The pressure inside the suction cup was retained by changing the position of lock of the three‐way tap. The pressure was measured by connecting the three‐way tap to a vacuum gauge. The apparatus remained adhered to the donor area because of negative pressure. The blister was formed in about 1.5 h. The roof of the blister was grafted onto the dermabraded recipient site.

Results The pigmentation was complete in 20 out of 22 patients. There were no complications.

Conclusions The technique is inexpensive and easy and obviates the need of cumbersome and heavy equipment.
Basal cell carcinoma of the lower extremities
Authors: Pearson Greg , King Lloyd E. , Boyd Alan S.
Published: March 2003

Background The most common malignancy in the USA is basal cell carcinoma. It is most prevalent on the head and neck, but can occur elsewhere. We sought to determine the frequency of basal cell carcinomas arising on the lower extremities, as well as the gender of affected patients, the histologic subtype, and the specific sites of involvement.

Methods We reviewed cases submitted to the Vanderbilt Dermatopathology Service between 1994 and 1997 which were diagnosed as basal cell carcinoma. A subset of 150 cases which arose on the lower extremities and a control group of 150 cases which arose at other anatomic sites were studied further.

Results A significantly greater number of basal cell carcinomas of the lower extremities arose in women, were of the superficial subtype, and were found below the knee; 59% of basal cell carcinomas in both sexes arose on the right limb.

Conclusion Basal cell carcinomas of the lower extremities occur more often in women in the USA and are of the superficial subtype. This may be due to differing patterns of dress and exposure to the sun.
Psoralen–ultraviolet A therapy vs. psoralen–ultraviolet B therapy in the treatment of plaque‐type psoriasis: our experience with Fitzpatrick skin type IV
Authors: Khurshid Khawar , Haroon T. S. , Hussain I. , Pal S. S. , Jahangir M. , Zaman T.
Published: March 2003

Abstract

Background  Oral psoralen, when combined with UVB, shows an increased response in psoriasis. In this study, conventional psoralen–UVA (PUVA) therapy was compared with psoralen–UVB (PUVB) therapy in plaque‐type psoriasis in patients with Fitzpatrick skin type IV.

Patients and methods  Equal numbers of patients with stable, plaque‐type psoriasis were treated with either PUVA (n = 22) or PUVB (n = 22), three times weekly until 90% clearance was achieved. A final evaluation was made 3 months later.

Results  The two groups showed no significant differences in terms of clearance of disease, mean number of exposures, or the average duration of therapy; however, the cumulative dose of UVB required for clearance was significantly lower than that of UVA. Both groups had a similar acute side‐effects' profile.

Conclusions  PUVB therapy is as effective as conventional PUVA in the treatment of stable, plaque‐type psoriasis in patients with Fitzpatrick skin type IV. A significantly lower dose of UVB is required for clearance as compared with UVA.
Cutaneous and gastrointestinal tract hemangiomas associated with disappearing bones: Gorham syndrome
Authors: Hsu Te‐Shao , Cooper Leslie T. , Maus Timothy P. , Miller Edmund A. , Barlow James H. , Davis Mark D. P.
Published: March 2003

A 42‐year‐old woman presented with a 15‐year history of increasingly severe headaches. Since birth, she had hemangiomas involving predominantly her sacrum and rectum that were associated with episodes of rectal and back pain and hematochezia. During adolescence, she had multiple surgical procedures to repair the hemangiomas. Her family had no history of similar disease.

Parietal headaches developed at age 27 years. Radiographic evaluation revealed destructive lesions of the cranium, the right scapula, the symphysis pubis, and the sacroiliac joint. Her headaches were managed conservatively with pain medication and observation. When her headaches steadily worsened, she was referred to our institution for another opinion.

On physical examination, her skull appeared flattened bilaterally (Fig. 1) and was soft to palpation. Multiple, flesh‐colored skin polyps involving the sacral areas were noted (Fig. 2); these were 3‐4 cm in diameter, soft, and compressible.

Patient’s skull appears flattened bilaterally with an asymmetric contour

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Hemangiomas are present in the sacral area

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Radiographic examination of the skull showed extensive bony defects involving the parietal areas bilaterally and extending into the right occipital region (Fig. 3). A review of the results of the patient's previous radiographic studies beginning in 1982, including computed tomographic scans and magnetic resonance imaging, demonstrated lytic lesions consistent with osseous hemangiomas, with significant progression in the size and extent of the lytic areas in 1997 and 1998. A sheath of soft tissue was noted at the sites of the former bones. The studies showed mixed sclerotic and lytic lesions involving the right humerus and multiple bony lesions of the left superior and inferior pubic rami with associated destruction at the pubic symphysis.

Coronal computed tomographic scan through the level of the temporomandibular joint shows bony defects

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Extended upper gastrointestinal tract endoscopy showed exophytic jejunal hemangiomas and a gastric hemangioma. Colonoscopy displayed no evidence of vascular malformation. Laboratory tests showed mild normocytic anemia. Results of other laboratory investigations were unremarkable. The patient refused a skin biopsy.

The headaches were believed to be related to the mass effect of the enlarging hemangiomas of the skull. Because a trial of valproic acid gave only minimal relief, the decision was made to use radiotherapy for the involved bones (cranium, pelvis, and humerus). A total of 34 Gy was delivered in 17 fractions. The patient reported an improvement in her headaches, which is sustained a year later. Follow‐up radiographic studies at the end of treatment showed no progression of the osseous hemangiomas.
Acquired immunodeficiency syndrome‐related oral and/or cutaneous histoplasmosis: a descriptive and comparative study of 21 cases in French Guiana
Authors: Couppié Pierre , Clyti Emmanuel , Nacher Mathieu , Aznar Christine , Sainte‐Marie Dominique , Carme Bernard , Pradinaud Roger
Published: March 2003

Background Oral or cutaneous acquired immunodeficiency syndrome (AIDS)‐related histoplasmosis is a rare presentation of disseminated histoplasmosis.

Objective To describe this clinical presentation and to compare it with other forms of AIDS‐related disseminated histoplasmosis.

Methods A cross‐sectional study of patients with AIDS‐related disseminated histoplasmosis was performed. CD4 counts and survival were compared between patients with oral or cutaneous histoplasmosis and patients with nonmucocutaneous disseminated histoplasmosis.

Results The mean CD4 lymphocyte count was lower in patients with mucocutaneous lesions than in patients with nonmucocutaneous disseminated histoplasmosis (29 vs. 72/mm3, P = 0.002). The proportion of survivors 1 month after diagnosis did not differ significantly between the two groups (13/21 vs. 32/45, P = 0.4). At 6 months, the proportion of survivors was significantly lower for patients with mucocutaneous lesions (6/21 vs. 22/39, P = 0.03).

Conclusions These results suggest that mucocutaneous lesions occur at a later stage of human immunodeficiency virus infection, but are not, in themselves, associated with a higher level of mortality. The excess mortality at 6 months reflects deaths from other complications of severe immunodepression. This study confirms the polymorphism of mucocutaneous lesions, emphasizing the need for systematic testing for Histoplasma in all cases of mucocutaneous lesions in AIDS patients.
The genetic epidemiology of psoriasis vulgaris in Chinese Han
Authors: Zhang Xuejun , Wang Hongyan , Te‐shao Hsu , Yang Sen , Chen Shanyu
Published: March 2003

Background The aim of this study was to explore the effects of genetic factors on the onset of psoriasis vulgaris and to develop a possible genetic model of psoriasis in Chinese Han.

Methods Data for 1043 patients with psoriasis vulgaris were obtained by questionnaire. Complex segregation analysis and heritability were performed using Penrose's method, Falconer's method, and the epi info 6.0 and sage‐regtl programs.

Results (1) For male and female patients, the peak ages of initial onset were 30–39 and 10–19 years, respectively, with the mean age of initial onset being 27.69 ± 12.32 years in males and 23.26 ± 12.56 years in females. (2) Of 1043 patients with psoriasis, 326 (31.26%) were reported to have a family history of psoriasis. The onset for males with a family history of psoriasis was earlier than that for those without a family history (P < 0.01). The morbidities of first‐degree relatives were 7.67% in patients with type I psoriasis and 5.27% in patients with type II (P < 0.01), and those of second‐degree relatives were 1.04% in type I and 0.24% in type II (P < 0.01). (3) The onset of psoriasis was earlier in females than in males in type I psoriasis (P < 0.01), but this was not the case in type II (P > 0.05). (4) The prevalence of psoriasis in first‐ and second‐degree relatives of the proband with psoriasis was 7.24 and 0.95%, respectively; higher than that in the general population (0.146%). (5) The heritability of psoriasis in first‐ and second‐degree relatives was 67.04 and 46.59%, respectively. The Mendelian, no‐major‐gene and environment model was rejected by complex segregation analysis.

Conclusion Psoriasis vulgaris follows a pattern of polygenetic or multifactorial inheritance rather than single‐gene inheritance.
Atypical varicella with palm and sole involvement
Authors: Auvin Stéphane , Catteau Benoît , Ganga‐Zandzou Patrice‐Serge , Ythier Hubert
Published: March 2003

Varicella is a common disease characterized by a typical presentation. We report a case of an atypical presentation of varicella with a centrifugal distribution, eruption with many vesicles, no pustular stage in evolution and distal involvement. There were none of the known modifying factors (immunosuppression, skin disease, injury or sun exposure). To explain the distal involvement, we suggest intraepidermic lesions caused by a pre‐existing B1 coxsackie infection.
Cutaneous ciliated cyst on the cheek in a male
Authors: Ohba Norihiro , Tsuruta Daisuke , Muraoka Michinari , Haba Tomoko , Ishii Masamitsu
Published: March 2003

A 53‐year‐old man presented with a 2‐year history of a painless mass on the right cheek. On physical examination, the lump was a solitary, well‐demarcated, mobile lesion. There was no abnormality in the surrounding skin. Ultrasonography demonstrated a single, cystic, well‐defined, subcutaneous cyst, measuring 20 mm in diameter. Laboratory tests, including sex hormones, were within the normal range. The tumor was resected surgically under local anesthesia. The cyst had a slightly yellow wall and contained clear, watery fluid. The patient had no other medical problems and no history of other skin disease.

Histopathologically, the unilocular cyst was lined with two layers of epithelium and was devoid of papillary infolding. The inner layer of the cyst was composed of cuboidal to columnar epithelial cells, most of which demonstrated prominent cilia. The outer layer consisted of polygonal cells that contained clear cytoplasm (Fig. 1). No foci of squamous metaplasia were present and the cyst wall did not contain adnexal structures. The inner layer of the epithelium was positive for periodic acid–Schiff (PAS) stain, but contained no diastase‐resistant granules.

Hematoxylin and eosin staining. A unilocular cyst lined with two layers of epithelium (original magnification, × 200)

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Immunohistochemical staining revealed strong staining in the membrane for epithelial membrane antigen (EMA) and diffuse cytoplasmic reaction to cytokeratin in the epithelial component, but carcinoembryonic antigen (CEA) staining was negative. Staining for α‐smooth muscle actin (αSMA) and S‐100 protein was positive in the outer layer (Fig. 2), suggesting myoepithelial cells. There were no desmin, vimentin, amylase or estrogen receptor‐positive cells in the epithelium.

α‐Smooth muscle actin (αSMA) staining was positive in the outer layer (original magnification, × 100)

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Women's views of two interventions designed to assist in the prophylactic oophorectomy decision: a qualitative pilot evaluation
Authors: Bhavnani Vanita , Clarke Aileen , Dowie Jack , Kennedy Andrew , Pell Ian
Published: March 2003

Introduction  A qualitative pilot evaluation of two different decision interventions for the prophylactic oophorectomy (PO) decision: a Decision Chart and a computerized clinical guidance programme (CGP) was undertaken. The Decision Chart, representing current practice in decision interventions, presents population‐based information. The CGP elicits individual values to allow for quality‐adjusted life years to be calculated and an explicit guidance statement is given. Prophylactic oophorectomy involves removal of the ovaries as an adjunct to hysterectomy to prevent ovarian cancer. The decision is complex because the operation can affect a number of long‐term outcomes including breast cancer, coronary heart disease and osteoporosis.

Methods  Both interventions were based on the evidence and were administered by a facilitator. The Decision Chart is a file, which progressively reveals information in the form of bar charts. The CGP is a decision‐analysis based program integrating the results from a cluster of Markov cycle trees. The research evidence is incorporated with woman's individual risk factors, values and preferences. A purposive sample of 19 women awaiting hysterectomy used the decision interventions (10 CGP, nine Decision Chart). In‐depth semi‐structured interviews were undertaken. Interviews were transcribed and analysed to derive themes.

Results  Reactions to the different decision interventions were mixed. Both were seen as clarifying the decision. Some women found some of the tasks difficult (e.g. rating health status). Some were surprised by the ‘individualized’ guidance, which the CGP offered. The Decision Chart provided some with a sense of empowerment, although some found that it provided too much information.

Conclusions  Women were able to use both decision interventions. Both provided decision clarification. Problems were evident with both interventions, which give useful pointers for future development. These included the possibility for women to see how their individual risks of different outcomes are affected in the Decision Chart and enhanced explanation of the CGP tasks. Future design and evaluation of decision aids, will need to accommodate differences between patients in the desire for amount and type of information and level of involvement in the decision‐making process.
Fertility interactions in Drosophila: Theoretical model and experimental tests
Authors: Moya Andrés , Ayala Francisco J.
Published: March 2003

The results of 11 experiments with Drosophila species show that fertility is not a reducible property: the fertility of a mating pair cannot be predicted from the average fertility of the two genotypes involved. We propose a model of fertility selection that does not assume additivity (or multiplicativity) but assumes random mating and that the genotypic frequencies are in Hardy‐Weinberg equilibrium. Numerical simulations show that removal of the assumption of Hardy‐Weinberg frequencies does not significantly change the equilibrium frequencies predicted by the model.
Ancestral patterns in bird limb development: A new look at Hampé's experiment
Authors: Müller Gerd B.
Published: March 2003

The “Archaeopteryx limb” of experimentally treated bird embryos has become a standard quotation in the growing literature on developmental factors in evolution. It has not only been claimed that an early manipulation of the chick limb produces a series of atavistic skeletal features, but the experiment is also frequently interpreted within a genome‐centered concept of atavism. The present study provides a morphological, quantitative, and comparative analysis of the skeletal and muscular reactions to the classic barrier insertion experiment of Hampé. The main result of this operation, traditionally seen as a “full length fibula”, is shown to be a relative effect due to tibia shortening, while all the other ancestral skeletal features, which are usually pointed out as being provoked by the elongated fibula, do not appear. The experimentally generated fibula/tibia length ratio and distance, however, mimic the pattern in developing reptilian limbs and are seen to induce secondary effects in the muscular system that are reminiscent of archosaur reptiles. Similar muscle patterns are found as interspecific variations in several bird species. The revised view of the skeletal changes and the additional data on muscular effects allow for a renewed interpretation of the experiment, shifting the emphasis from atavisms to the role of heterochrony, developmental integration, and epigenetic constraint in the evolutionary modification of organismic structures.
Novel chloroplast DNA polymorphism in a sympatric region of two pines1
Authors: Govindaraju Diddahally R. , Dancik Bruce P. , Wagner David B.
Published: March 2003

Nine hundred and two individuals from two populations in a Pinus banksiana — P. contora sympatric region were classified by restriction fragment length polymorphisms of two polymorphic chloroplast DNA markers. A large number of novel chloroplast DNA variants were identified which have not been observed in the allopatric ranges of the two parental species. Three apparently recombinant chloroplast DNA genotypes were discovered, in each of which one marker was typical of P. banksiana and the other was typical of P. contorta. These unusual sympatric chloroplast DNA's are evidence that the genetic complexity and rare variants of hybrid zones are not limited to the nuclear genome.
Development of the dimorphic anthers in Collomia grandiflora; evidence for heterochrony in the evolution of the cleistogamous anther
Authors: Lord E. M. , Eckard K. J. , Crone W.
Published: March 2003

A modification characterizing all cleistogamous species is reduction in anther size of the CL (cleistogamous or closed) flower. In Collomia grandiflora the CL anther, in addition to being smaller, has only two locules; the CH (chasmogamous or open) flower anther has four locules. As a consequence, there is a modification in CL anther shape. From initially similar primordia, a divergence in histology between the two anther forms appears at archesporial cell differentiation when only two locules are established in the CL anther. The process of form divergence in the two anther types is examined in this study using histological, allometric, and 3‐D computer graphic techniques. Allometric data from SEM images demonstrates the equivalence of primordial shapes at anther inception and divergence just prior to archesporial cell division, which signals the onset of sporogenous cell proliferation. Reconstructions of the anthers at archesporial cell division stage revealed differences in external and internal form and size, features unrelated to locule number. Fewer initial archesporial cells and a shorter duration of sporogenous cell proliferation in the CL anther correlates with a smaller anther with 1/10th the number of pollen grains at maturity. The CL anther shows less cell division activity from the time of archesporial cell division and no trace of the intercalary growth which appears during meiosis in the CH anther. The divergent CL anther size and form may be attributed to an earlier onset of abaxial locule differentiation in a smaller primordium which may itself preclude adaxial locule initiation. Heterochrony, or alteration in developmental timing, is proposed as the mode of evolution of the CL from the ancestral CH form.
Allozyme divergence between different gene arrangements in Drosophila subobscura
Authors: Pinsker W. , Böhm I.
Published: March 2003

Allozyme and chromosomal polymorphism were analysed simultaneously in three population samples of Drosophila subobscura from Scotland, Germany and Italy. The study revealed significant genic divergence between the various chromosomal gene arrangements for the loci Acph, Lap and Pep, which are located inside inversions. No difference was found with the loci Me and Odh, which are both on the same chromosome but proximal to the structurally polymorphic region. Samples of a given gene arrangement taken from the different localities are genetically uniform. The data indicate that the observed non‐random associations between enzyme genes and chromosomal inversions are the result of inhibited recombination in heterokaryotypes and gradual differentiation of the separated gene pools, rather than selection and coadaptation.
On the genetical basis of the laying‐date in an island population of blue tits
Authors: Blondel Jacques , Perret Philippe , Maistre Marie
Published: March 2003

There are striking differences in life‐history traits associated with reproduction, between an insular population of the blue‐tit and one on the nearby mainland. In order to test the extent to which these differences are genetic, two samples of birds, one from Corsica and one from mainland southern France, were hand‐raised. These birds bred subsequently in aviaries at Montpellier during three consecutive years, at the same date and in the same way as did the natural populations from which they came. It is concluded that the difference in laying‐date between the two samples has a genetic basis. The adaptation to each particular set of environmental conditions is discussed.
Effects of exposure to short‐term heat stress on fitness components in Drosophila melanogaster
Authors: Krebs Robert A. , Loeschcke Volker
Published: March 2003

Effects of thermal stress on survival and reproductive success in ten recently collected isofemale lines of Drosophila melanogaster were compared for flies treated as follows: always held at 25° C, placed in an incubator set at 37° C for 120 min, or exposed to 40° C in an incubator for 90 min, with or without previous exposure to 37° C. Short‐term exposure to the higher temperature greatly reduced adult survival, the mating frequency of males and females, and female fecundity, which was measured as offspring produced over ten days. Male fertility, measured as the progeny produced by a female mated once, differed little among treatments. Previous exposure to a high, but non‐lethal, temperature before exposure to the higher one, improved survival of males and females, and improved offspring production of females. Genetic variation was present among lines for offspring production, but genetic variation for survival was not significant, and genotype by environment interactions for fitness components of females were small. These results indicated low genetic variation in thermal resistance in the studied population, such that a threshold for temperature stress probably exists, above which local extinction is more likely than the evolution of resistance.
Sociogenetic organization of the ants Myrmica ruginodis and Myrmica lobicornis: Number, relatedness and longevity of reproducing individuals
Authors: Seppä Perttu
Published: March 2003

The number and relationships of reproducing individuals create the observed genetic heterogeneity within a social insect colony. These are referred to as sociogenetic organization and were studied in the red ants M. ruginodis and M. lobicornis. Direct observations of the queen numbers were obtained by excavating colonies. The effective number of reproducing individuals was estimated from genetic relatedness based on genotype frequency data. Sociogenetic organization of colonies of both species is simple. The number of queens is low, single mating of queens is the rule and queen to queen variation in worker production is minor. The important variables of sociogenetic organization are the number and relatedness of coexisting queens in polygynous colonies. Queen nestmates are related on average by 0.405 in polygynous colonies of M. ruginodis, showing that colonies recruit their own daughters as new reproductives. The distribution of queen number in M. ruginodis indicates that the study population contains both microgyna and macrogyna types of the species. The large proportion of colonies where the resident queen(s) is not the mother of the workers shows that the average life span of a queen is short and colonies are serially polygynous.
Segretation distortion in a deme-structured population: opposing demands of gene, individual and group selection
Authors: Boven M. Van , Weissing
Published: March 2003

The evolution of segregation distortion is governed by the interplay of selection at different levels. Despite their systematic advantage at the gamete level, none of the well-known segregation distorters spreads to fixation since they induce severe negative fitness effects at the individual level. In a deme-structured population, selection at the population level also plays a role. By means of a population genetical model, we analyse the various factors that determine the success of a segregation distorter in a metapopulation. Our focus is on the question of how the success of a distorter allele is affected by its segregation ratio and its fitness effects at the individual level. The analysis reveals that distorter alleles with high segregation ratios are the best invaders and reach the highest frequencies within single demes. However, the productivity of a deme harbouring a distorter with a high segregation ratio may be significantly reduced. As a consequence, an efficient distorter will be underrepresented in the migrant pool and, moreover, it may increase the probability of deme extinction. In other words, efficient distorters with high segregation ratios may well succumb to their own success. Therefore, distorters with intermediate segregation ratios may reach the highest frequency in the metapopulation as a result of the opposing forces of gamete, individual and group selection. We discuss the implications of this conclusion for the t complex of the house mouse.
Selfing versus outcrossing propensity of the fungal pathogen Microbotryum
violaceum across Silene
latifolia host plants: O. KALTZ AND J. A. SHYKOFF
Authors: Kaltz  , Shykoff
Published: March 2003

In the fungal pathogen Microbotryumviolaceum mating (i.e. conjugation between cells of opposite mating type) is indispensable for infection of its host plant Silenelatifolia. Since outcrossing opportunities are potentially rare, selfing may be appropriate to ensure reproduction. On the other hand, outcrossing may create genetic variability necessary in the coevolutionary arms race with its host.

We investigated the propensity of M. violaceum to outcross vs. self in different host environments. We used haploid sporidia from each of three strains from five fungal populations for pairwise mixtures of opposite mating type, representing either selfing or outcrossing combinations. Mixtures were exposed to leaf extract from seven S. latifolia plants. The proportion of conjugated sporidia quantified mating propensity.

The identity of both fungal strains and host influenced conjugation. First, individual strains differed in conjugation frequency by up to 30%, and strains differed in their performance across the different hosts. Second, selfing combinations produced, on average, more conjugations than did outcrossing combinations. Selfing appears to be the predominant mode of reproduction in this fungus, and selfing preference may have evolved as a mechanism of reproductive assurance. Third, individual strains varied considerably in conjugation frequency in selfing and outcrossing combinations across different hosts. This indicates that conjugation between outcrossing partners could be favoured at least in some hosts. Since the dikaryon resulting from conjugation is the infectious unit, conjugation frequency may correspond with infection probability. This assumption was supported by an inoculation experiment, where high infectious sporidial dosage resulted in higher infections success than did low dosage. We therefore predict that sexual recombination can provide this pathogen with novel genotypes able to infect local resistant hosts.
Wolbachia infection and incompatibility dynamics in experimental selection lines
Authors: Perrot-Minnot  , Werren
Published: March 2003

High and low levels of Wolbachia-induced cytoplasmic incompatibility (CI) were selected for in the parasitic wasp Nasonia vitripennis, in the single-infected strain Ti277. After nine generations of selection, males from lines selected for high incompatibility level (HI lines) were significantly more incompatible with uninfected females (AsymC) than the maternal strain. The reverse response, a full compatibility with AsymC, was observed in eight out of 12 lines selected for low incompatibility (LO lines), correlated with loss of Wolbachia infection. Bacterial density estimates in the eggs of some HI lines increased significantly. The procedure for line maintenance resulted in introgression of AsymC nuclear genome into the Ti277 background. Significant changes of CI level and bacterial density due to the introgression were also observed in the control lines, possibly reflecting an effect of host genotype on bacterial density and CI. After selection had been relaxed for six generations, bacterial density in the five high-infected HI lines declined back to a level comparable to the other lines. The data are consistent with the ‘bacterial dosage’ model, but with an upper threshold of bacterial infection above which there is no correlation between infection level and CI level. We further investigate the maternal transmission of bacterial density by a mother–daughter regression on bacterial density. The pattern observed is consistent with a density dependent regulation of bacterial numbers around an ‘equilibrium’ density, independent of any effects of CI. The equilibrium value is likely to be determined by both bacterial strain and host genotype.
Optimal rates of bisexual reproduction in cyclical parthenogens with density-dependent growth
Authors: Serra  , King
Published: March 2003

This work explores theoretical patterns of reproduction that maximize the production of resting eggs and the long-term fitness of genotypes in cyclical parthenogens. Our focus is on density-dependent reproduction as it influences the consequences of a trade-off between producing amictic daughters – which reproduce parthenogenetically and subitaneously – and producing mictic daughters – which undergo meiosis and bisexual reproduction. Amictic females increase competitive ability and allow the population to achieve a larger size; mictic females directly contribute to population survival through harsh periods by producing resting eggs. Although morphologically indistinguishable, the two types of females differ greatly in their ecological and reproductive roles. What factors underlie the differential allocation of resources to produce amictic and mictic females?

Using a demographic model based on readily accessible parameters we demonstrate the existence of a frequency of mictic females that will maximize the population's long-term fitness. This frequency, termed the optimal mictic ratio, mo, is 1 − (q/b)1/2, where q is the mortality rate and b is the maximum birth rate. Using computer simulation we compared the fitness of a population with this constant mictic ratio with populations having multiple switches from complete parthenogenetic growth to complete allocation in mixis (mictic ratio either 0 or 1). Two important conclusions for optimal mixis in density-dependent growth conditions are: (1) intermediate mictic ratios are optimal, and (2) optimal mictic ratios are higher when habitat conditions are better. Physiological cues responding to differences in birth and death rates are common so that it is possible that populations may adjust their relative rates of mictic and amictic female production in response to environmentally induced changes to the optimum mictic ratio. Our analysis demonstrates that different patterns of mixis are expected in different type of habitats. Since the optimal mictic ratio is sensitive to the effects of a variety of environmental challenges, our model makes possible a new means to evaluate life history evolution in cyclical parthenogens.
Habitat-specific variation in life-history traits, clonal population structure and parasitism in a freshwater snail (Potamopyrgus antipodarum)
Authors: Jokela  , Dybdahl  , Lively
Published: March 2003

High risk of infection by parasites may select for early reproduction in natural host populations. In a previous study of a freshwater snail (Potamopyrgus antipodarum) we found (1) that different clones of the snail are associated with different depth-structured vegetation zones and (2) that snails in shallow water, where the age-specific risk of infection is highest, mature at a smaller size than snails in deeper habitats. This result suggests that there has been selection for early reproduction in these snails, and that different clonal genotypes have different life-history strategies. Alternatively, the observed life-history variation in the snails might be due to ecological factors that are independent of parasites, but correlated with depth. In the present study, we decoupled parasitism and depth by examining life histories and clonal population structure in a second lake (Lake Tennyson) where the mean prevalence of trematode parasites was low and unrelated to depth. Consistent with the previous results, clones were structured according to vegetation zones in Lake Tennyson. However, we found no relationship between depth and life-history traits, which is inconsistent with the idea that depth-associated factors other than parasites affect snail life histories. Taken together, these results suggest that life-history variation is more likely to result from a depth-specific risk of infection than from depth per se, and that partitioning of habitat zones by different groups of clones may be a general phenomenon in P. antipodarum populations.
The effects of pathogen infection and mutation on life-history characters in Arabidopsis thaliana
Authors: Peters
Published: March 2003

The nature of the interaction among deleterious mutations is important to models in many areas of evolutionary biology. In addition, interactions between genetic and environmental factors may affect the predictions of such models. Individuals of unknown genotypes of Arabidopsis thaliana, ecotype Marburg, were exposed to five levels of chemical (EMS) mutagenesis and three levels of Pseudomonas syringae infection. Survival, growth and flowering characteristics of each individual were measured. The logarithm of fitness is expected to be a linear function of mutation number if mutations act independently. Furthermore, the expected number of mutations should be approximately a linear function of time of exposure to mutagen. Therefore, nonlinear effects of mutagen exposure on the logarithm of fitness characters would suggest epistasis between mutations. Similarly, if pathogen infection and mutation act independently of each other, their effects should be additive on a log scale. Statistical interactions between these factors would suggest they do not act independently; particularly, if highly mutated individuals suffer more when infected than do less mutated individuals, this suggests that pathogens and mutations act synergistically. Pseudomonas-infected individuals were shown to have an increased probability of flowering under conditions of short day length, but to ultimately produce fewer flowers than uninfected individuals. This suggests a plastic response to stress and, despite that response, an ultimately deleterious effect of infection on fitness. Leaf rosette growth was negatively and linearly related to the expected number of mutations, and the effects of mutation on different life-cycle stages appeared to be uncorrelated. No significant interactions between pathogen and mutation main effects were found. These results suggest that mutations act multiplicatively with each other and with pathogen infection in determining individual fitness.
Genes affecting phenotypic plasticity in Arabidopsis: pleiotropic effects and reproductive fitness of photomorphogenic mutants
Authors: Pigliucci  , Schmitt
Published: March 2003

Many plants exhibit characteristic photomorphogenic shade ’avoidance’ responses to crowding and vegetation shade; this plasticity is often hypothesized to be adaptive. We examined the contribution of specific photomorphogenic loci to plastic shade avoidance responses in the annual crucifer Arabidopsis thaliana by comparing single-gene mutants defective at those loci with wild type plants exhibiting normal photomorphogenesis. The hy1 and hy2 mutants, deficient in all functional phytochromes, were less plastic than the wild type in response to a nearby grass canopy or to a low-red/far-red light ratio characteristic of vegetation shade. These mutants displayed constitutively shade-avoiding phenotypes throughout the life cycle regardless of the treatment: they bolted at an earlier developmental stage and were characterized by reduced branching. In contrast, the hy4 mutant, deficient in blue light reception, exhibited greater plasticity than the wild type in response to vegetation shade after the seedling stage. This mutant produced more leaves before bolting and more basal branches under normal light conditions when compared to the wild type. These results indicate that specific photomorphogenic loci have different and sometimes antagonistic pleiotropic effects on the plastic response to vegetation shade throughout the life cycle of the plant. The fitness of the constitutively shade-avoiding phytochrome-deficient mutants was lower than that of the plastic wild type under normal light, but was not different in the vegetation shade treatments, where all genotypes converged toward similar shade avoidance phenotypes. This outcome supports one key prediction of the adaptive plasticity hypothesis: that inappropriate expression of shade avoidance traits is maladaptive.
Circularity, evolution, systematics … and circularity
Authors: Lee
Published: March 2003

Many have argued strongly that incorporation of evolutionary theory into systematics is dangerously circular, while others have maintained that such an integrated approach increases the accuracy of phylogenetic inference. Here, it is demonstrated that such blanket statements regarding exclusion or inclusion of evolutionary principles in systematics fail to distinguish between two very different types of principles. ‘Phylogeny-neutral’ evolutionary principles are those inferred without any recourse to specific phylogenetic hypotheses (e.g. via developmental genetics, biomechanics). In contrast, ‘phylogeny-dependent’ principles are those which can only be inferred on the basis of specific phylogenetic hypotheses (e.g. character associations detected via ‘comparative methods’). Inclusion of phylogeny-neutral principles in systematic studies as a priori assumptions can be justified, since these principles have (often strong) external empirical support from other spheres of investigation. However, inclusion of phylogeny-dependent principles in systematic studies is circular, since such principles have no external empirical support but are themselves derived from systematic studies. Advocating inclusion or exclusion of all (or as many as possible) evolutionary principles from phylogenetic analysis is therefore misguided. Rather, phylogeny-neutral principles are independently supported and can be included, while phylogeny-dependent principles are unjustified assumptions and should be excluded to avoid circularity. However, integration of complex phylogeny-neutral principles in systematics can create operational problems, even though there are no methodological reasons against their inclusion.
Pollen transfer dynamics and the evolution of gametophytic self-incompatibility
Authors: Steinbachs  , HolSinger
Published: March 2003

Recent studies of mating system evolution have attempted to include aspects of pollination biology in analysis of both theoretical models and experimental systems. In light of this growing trend, we propose a simple population genetic model for the evolution of gametophytic self-incompatibility, incorporating parameters for pollen discounting and pollen export/capture. In this model, we consider several cases that span the spectrum for dominance of the mutant self-incompatibility allele and for the degree of incompatibility conferred by the allele. We confirm earlier results that inbreeding depression is required for successful invasion of the self-incompatibility allele and we demonstrate that, unless pollen discounting is very low, the level of inbreeding depression must be very high for an allele conferring self-incompatibility to become established. Finally, we show that the dominance of the mutant allele has a greater impact on the fate of a newly arisen self-incompatibility allele than the strength of the incompatibility conferred by the allele. In particular, the more recessive the self-incompatibility expression in heterozygote stigmas and the weaker the response induced, the easier it is for a self-incompatibility allele to invade.
Convergent evolution of the mating behaviour of founder-flush populations of the housefly
Authors: Meffert L. M. , Regan J. L. , Brown B. W.
Published: March 2003

Courtship bouts of six founder-flush populations (two-pair founder-flush) and two nonbottlenecked controls of the housefly were videotaped over the course of 26 generations in order to evaluate the stability of mating behaviour. Limited-choice mate preference tests were conducted periodically to assess levels of homogamic preference. Both founder-flush and control treatments showed significant evolutionary potential in courtship, along with homogamic and heterogamic preferences. The founder-flush populations were significantly differentiated from the controls in courtship repertoire, but all of the populations pursued convergent evolutionary trajectories in adapting to the laboratory, resulting in dissolution of homogamic preferences. The phenotypic shifts in courtship and mate preferences were unrelated to evolutionary trends in overall mating vigour; therefore, the convergence in courtship could not be attributed to either a fitness meltdown due to inbreeding or the purge of deleterious alleles. Only one founder-flush population showed some independence from the selectional pressures for convergence; therefore, the single two-pair founder-flush event was generally inadequate to stimulate stable incipient speciation. This study thus demonstrates how convergent evolution can dissolve founder-flush effects.