bluuebunny/crossref_metadata_2025 huggingface dataset:
Lesional T‐cell subset in leprosy and leprosy reaction
Authors: Mahaisavariya Punkae , Kulthanan Kanokvalai , Khemngern Supakan , Pinkaew Sumruay
Published: March 2003

Background The T‐cell‐mediated immune response plays an important role in leprosy. The in situ proportion and pattern of distribution of T‐cell subsets in leprosy skin lesions have been studied, but no conclusion could be drawn.

Methods We used monoclonal antibodies for T‐helper and T‐suppressor surface antigen to define the nature of dermal infiltration in 17 cases of nonreactional leprosy and 20 cases of reactional leprosy.

Results We found T helper admixed with T suppressor in an aggregated pattern in the granulomas of most cases of nonreactional leprosy and in type I reactional leprosy, but a diffuse infiltrate throughout the dermis of type II reactional leprosy. The T‐helper/suppressor ratio was 1.68 in tuberculoid and 1.5 in lepromatous cases. The T‐helper/suppressor ratios of borderline tuberculoid (3.11) and type I reactional leprosy (2.54) were not statistically different. The T‐helper/suppressor ratio of type II reactional leprosy (5.83) was statistically higher than nonreactional lepromatous cases.

Conclusions The alteration of the T‐helper/suppressor ratio in our study is mainly due to the reduction of T‐suppressor cells in the dermal infiltrates, especially in type II reactional leprosy. Further studies of T‐suppressor functions may be important in the pathogenesis of leprosy.
Bacteriologic and immunologic aspects of Gram‐negative folliculitis: a study of 46 patients
Authors: Neubert Uwe , Jansen Thomas , Plewig Gerd
Published: March 2003

Background Gram‐negative folliculitis is an infection with Gram‐negative rods that most often occurs as a complication of prolonged broad‐spectrum antibiotic therapy in patients suffering from acne and rosacea.

Methods The bacteriologic and immunologic findings are reported in 46 patients, 39 men and 7 women, aged 16–79 (median, 28) years, with Gram‐negative folliculitis. Hypersensitivity reactions to various microbial recall antigens as well as granulocyte functions were evaluated. Quantitative measurements of serum levels of immunoglobulin M, G, A, and E, total complement activity, complement factors C3 and C4, and alpha‐1‐antitrypsin were performed.

Results The Gram‐negative organisms most frequently cultivated from nares, facial skin, and pustules were Klebsiella spp., Escherichia coli, Enterobacter spp., and Proteus spp. In all patients, deviations of one or more immune parameters were detected, including lowered serum concentrations of immunoglobulin M and alpha‐1‐antitrypsin, and elevated levels of immunoglobulin E. The humoral and cellular parameters were not influenced by isotretinoin therapy of Gram‐negative folliculitis.

Conclusions These findings suggest that Gram‐negative folliculitis is not only a complication of long‐lasting antibiotic treatment of acne and rosacea, but might be an entity of its own. Immunologic factors may play a critical role in the pathogenesis of Gram‐negative folliculitis.
Azithromycin for the treatment of acne
Authors: Fernandez‐Obregon Adolfo C.
Published: March 2003

Background Acne affects a large number of young adults, including women, who often present with facial as well as truncal involvement. Systemic antimicrobial agents currently used for the reduction of inflammatory papules and cysts require frequent administration and are sometimes associated with uncomfortable side‐effects contributing to a decrease in compliance.

Methods Ninety‐nine episodes of inflammatory acne in 79 patients treated with oral antimicrobial agents were studied retrospectively over a period of 46 weeks. Patients were treated with tetracycline, erythromycin, minocycline, and doxycycline, the most commonly prescribed oral antimicrobials used to treat acne. Individuals that were unable to tolerate this therapy or had failed conventional therapy were treated with the azalide antibiotic azithromycin, given in a single oral 250‐mg dose three times a week. The other agents were administered daily in divided doses as is current practice. Patients were also on topical care.

Results The efficacy and reported side‐effects were examined for all agents. Significant improvement was noted in 4 weeks. All agents were effective in reducing inflammatory lesions and improving acne. Azithromycin produced a slightly higher percentage of patients with a greater than 80% reduction in their inflammatory acne lesions (85.7%) vs. an average of 77.1% for all other agents. All differences observed were not statistically significant.

Conclusions The results show that azithromycin is a safe and effective alternative in the treatment of inflammatory acne with few side‐effects and good compliance, and suggest the need for further investigation with a clinical trial that will compare the long‐term efficacy and tolerability.
Tinea pedis in Korean children
Authors: Jang Kyoung‐Ae , Chi Doo‐Hyun , Choi Jee‐Ho , Sung Kyung‐Jeh , Moon Kee‐Chan , Koh Jai‐Kyoung
Published: March 2003

Background Tinea pedis is an infrequent disease in children before the age of puberty. There are few epidemiologic and clinical data regarding cases of tinea pedis observed in children.

Materials and methods We prospectively collected all cases of tinea pedis in children diagnosed during the years 1995–1997. Only those showing a positive result with potassium hydroxide preparation were included in the study. We performed fungal cultures in Sabouraud’s agar in all cases to document the etiologic fungi. The clinical characteristics were investigated.

Results A total of 21 children, aged 3 months to 14 years, were included. Fifteen patients were boys and six were girls. The mean age was 7.1 years. All the children were otherwise healthy. Prior to the establishment of the diagnosis of tinea pedis, 17 patients (80.9%) were treated for eczema without improvement. The intertriginous type was most common (53.3%). The first or second toe‐webs were the sites of predilection (32.3%). Eighteen children (86%) had a family history of tinea pedis and more than half of cases (52.4%) showed occurrence in the summer. The results of fungal cultures were positive in 13 patients (57%). Trichophyton rubrum was the most commonly isolated pathogen (69.2%). The other associated dermatoses were onychomycosis (33.3%), atopic dermatitis (14%), plantar warts (10%), and chronic urticaria (5%). Tinea pedis and onychomycosis cleared after treatment with topical antifungals with or without systemic antifungals in all cases.

Conclusions Tinea pedis in children can occur more frequently than suspected. Our study shows the strong association with a family history and the seasonal relationship with occurrence in summer in more than half of cases. We suggest that tinea pedis should be considered in the differential diagnosis of foot dermatitis in children.
Chronic lymphocytic leukemia presenting as cutaneous and bone involvement
Authors: Stefanidou Maria P. , Kanavaros Panayotis E. , Tosca Androniki D.
Published: March 2003

An 84‐year‐old man had a 3‐year history of a progressive, painless, papulonodular eruption, that was particularly prominent on the face and extremities. Physical examination revealed firm, bluish‐red nodules and plaques, located on the tip of the nose, the cheeks, ears, and distal digits. Skin lesions produced a leonine facies (Fig. 1), deformities of the fingers and toes, finger clubbing, and onyxis. An identical lesion was seen on a postoperational scar on the left cheek. The mucous membranes were spared. The patient had anterior and posterior cervical and bilateral axillary lymphadenopathy and splenomegaly.

Leonine facies

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On admission, the peripheral blood count revealed 260,000/mm3 leukocytes (lymphocytes 97%, neutrophils 2%, and monocytes 1%), a hemoglobin level of 9.5 g/dL, and platelet count of 100,000/mm3. Hypogammaglobulinemia with reduction of immunoglobulin G (IgG) and IgM was found.

Radiography of the fingers showed multiple osteolytic lesions of the phalanges and phalangette destruction of the left median finger (Fig. 2a,b). Computed tomography of the chest and abdomen revealed bilateral axillary, mediastinal, and para‐aortic lymphadenopathy and spleen enlargement.

X‐Ray of the hands: (a)  multiple osteolytic lesions of the phalanges and (b)  partial destruction of the left median phalangette

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Skin biopsy specimens from the ear and finger lesions showed a massive nonepidermal leukemic infiltration in the papillary and reticular dermis, with a grenz zone consisting of small lymphocytes (Fig. 3).

Skin biopsy (hematoxylin and eosin, × 250). Massive leukemic infiltration consisting of small lymphocytes. Subepidermally, a grenz zone of connective tissue is noted

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Biopsy of the enlarged cervical lymph node showed a diffuse infiltration with lymphocytes. Tissue biopsy from a finger lytic lesion revealed infiltration of bone trabecular and fibrous tissue with a dense population of small‐ and medium‐sized lymphocytes. Immunohistochemical study of cutaneous and bone lesions showed that the infiltrate in both biopsies consisted mainly of B lymphocytes (CD20+, CD45R+, CD45Ro–, OPD4–).

Peripheral blood smear had a B‐cell phenotype (CD19 98%, CD20 97%, CD23 99%, CD25 40%, CD5 90%, HLA‐DR 100%). Bone marrow smear and immunophenotyping surface marker analysis found a diffuse pattern of B‐lymphocytic infiltration.

A diagnosis of B‐cell chronic lymphocytic leukemia stage C (Binet staging system), with specific cutaneous and bone lesions, was established.

The patient received chemotherapy with chlorambucil and methylprednisolone, which resulted in improvement of the hematologic profile. Two years later, the cutaneous lesions showed partial remission.
Rosacea fulminans (pyoderma faciale): successful treatment of a 3‐year‐old girl with oral isotretinoin
Authors: Firooz Alireza , Firoozabadi Mehdi Rashighi , Dowlati Yahya
Published: March 2003

A 3‐year‐old girl presented with several erythematous papules, pustules, cysts, and purulent discharging sinuses on the face. The lesions suddenly appeared on the cheeks 3 months previously and then rapidly extended to other areas of the face. She had been treated with a variety of topical and systemic antimicrobials (including erythromycin, cephalexin, dicloxacillin, and suIfamethoxazole‐trimethoprim) and topical corticosteroids with no effect. Examination revealed deep red erythema of facial skin with several papules, pustules, cysts, and draining sinuses on the cheeks, chin, perioral, and paranasal areas (Fig. 1). No comedones or signs of hidradenitis suppurativa were observed. The child was otherwise in good health. She did not have a family history of severe acne vulgaris.

Patient before treatment

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Routine laboratory tests, including complete blood count, blood chemistry, and urinalysis, were within normal limits. Bacterial cultures showed negative results. Her parents refused to give consent to perform a biopsy.

She was initially treated with oral erythromycin, 250 mg four times daily, oral prednisolone, 7.5 mg (0.5 mg/kg body weight) daily, tapered to zero in 2 weeks, 0.025% fluocinolone acetonide cream, and warm compresses for 2 weeks with moderate improvement. Then oral isotretinoin, 10 mg (0.75 mg/kg body weight) daily, was instituted. The lesions showed marked improvement after 4 weeks and disappeared completely after 8 weeks, leaving only a few pitted scars (Fig. 2). The treatment with isotretinoin was continued for a total of 24 weeks. She tolerated isotretinoin very well. She was followed for 1 year after completion of treatment with no relapse.

Patient after 8 weeks of treatment with oral isotretinoin

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Lichenoid photodermatitis associated with nimesulide
Authors: Tursen Umit , Kaya Tamer Irfan , Kokturk Aysin , Dusmez Duygu
Published: March 2003

An 81‐year‐old‐female patient presented with a 2 week history of erythematous to violaceous lichenoid papules and plaques exhibiting a reticulated pattern on the ‘‘V’' area of the chest and dorsal hands. Fine, whitish reticulated networks were present over the surface of many well developed papules. The lesions were sharply demarcated and moderately pruritic (Fig. 1).

 Violaceous lichenoid papules with reticular pattern located on the ‘‘V’' area of the chest

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The result of routine complete blood cell count, urinalysis, erythrocyte sedimentation rate, liver and kidney function tests were within normal limits. Antinuclear and anti‐DNA antibodies were negative, and total C3 and C4 complement levels were normal. Hepatitis B surface antigen, anti‐Hepatitis B surface antigen, anti‐Hepatitis B core IgM antibody were negative, while anti‐Hepatitis C virus antibody was positive. A skin biopsy specimen obtained from the neck of our patient revealed an interface lichenoid dermatitis accompanied by individual necrotic epidermal keratinocytes, parakeratosis and eosinophils in the infiltrate (Fig. 2).

 Interface lichenoid dermatitis accompanied by individual necrotic epidermal keratinocytes and parakeratosis (Hematoxylin and eosin; original magnification, × 200)

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Nimesulide therapy was stopped and the patient was treated with topical corticosteroids and systemic antihistamines. The eruption resolved within 5 days. The rash returned following nimesulide rechallenge.
Prurigo pigmentosa
Authors: Gür‐Toy Günes , Güngör Emel , Artüz Ferda , Aksoy Fehmi , Alli Nuran
Published: March 2003

Background Prurigo pigmentosa is a rare inflammatory dermatosis of unknown etiology characterized by recurrent, pruritic erythematous papules and gross reticulate hyperpigmentation. It is seen most commonly among young adult Japanese females. Only 20 cases have been described outside Japan.

Methods We report two female, Turkish patients aged 20 and 26 years who had a pruritic rash with the characteristic clinical appearance and supportive histopathology of prurigo pigmentosa.

Results They were successfully treated with minocycline and doxycycline.

Conclusions Prurigo pigmentosa is a relatively new clinical entity, and we believe that a more widespread knowledge of this disease will lessen its misdiagnosis. We find it noteworthy to point out that there may be a predisposition to prurigo pigmentosa amongst the Turkish and Sicilian populations.
Leukomelanodermic leprosy
Authors: Tomimori‐Yamashita Jane , Maeda Solange M. , Sunderkötter Cord , Kaminsky Silvia K. , Michalany Nilceo S. , Rotta Osmar , Castro Raimundo M.
Published: March 2003

A 39‐year‐old woman presented with a 6‐year history of asymptomatic macules on her back. The patient had no other complaints, and she did not report any case of infectious disease in her family. Examination revealed hyperpigmented macules, presenting irregular edges but with a sharp demarcation, on the midline of the back from the cervical to the lumbar region. Within these hyperpigmented areas, islands of normal appearing skin were observed. There were also some hypopigmented macules on the lateral and posterior aspects of the trunk (Fig. 1). The patient presented thickening of the left ulnar nerve and sensory loss to temperature on the lateral aspect of the left arm.

Hyperpigmented macules, presenting irregular but sharply demarcated edges, on the midline of the back. Islands of normal appearing skin are observed in these hyperpigmented areas. Hypopigmented macules on the lateral and posterior aspects of the trunk

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Biopsy specimens were obtained from the hyper‐ and hypopigmented areas. In the hyperpigmented macule, the biopsy revealed focal areas of hypomelanosis in the epidermis and the presence of melanophages in the superficial dermis, but no acid‐fast bacilli were found (Fig. 2a). The Masson–Fontana stain showed an evident pigmentary incontinence (Fig. 2b). The biopsy obtained from the hypopigmented lesion also revealed focal areas of hypomelanosis, but in the superficial dermis an infiltrate of foamy macrophages was observed, as typically found in lepromatous leprosy (Fig. 3a); acid‐fast bacilli were found by Fite–Faraco stain. The focal hypomelanosis was confirmed by Masson–Fontana stain (Fig. 3b). Mitsuda's reaction in this patient was negative and slit‐skin smears (cutaneous lesion, earlobes, elbows, and knees) were negative for acid‐fast bacilli.

Biopsy of hyperpigmented macule. (a) Focal areas of hypomelanosis and presence of melanophages in the superficial dermis (hematoxylin and eosin stain, ×100). (b) Evident pigmentary incontinence in the superficial dermis (Masson–Fontana stain, ×100)

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Biopsy of hypopigmented macule. (a) Focal areas of hypomelanosis in the epidermis and dermal infiltrate of foamy macrophages (hematoxylin and eosin stain, ×100). (b) Focal areas of hypomelanosis (Masson–Fontana stain, ×100)

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The patient was treated with multidrug therapy for multibacillary leprosy: rifampin, 600 mg once monthly (supervised), clofazimine, 300 mg once monthly (supervised), dapsone, 100 mg daily, and clofazimine, 50 mg daily, all given for 2 years. After 7 months of treatment, the hypopigmented lesions diminished and the hyperpigmented lesions improved after 2 years of treatment and the sensory loss to temperature was restored.
An open‐label study of the safety and efficacy of limited application of fluticasone propionate ointment, 0.005%, in patients with atopic dermatitis of the face and intertriginous areas
Authors: Tan Mei‐Heng , Meador Stacie L. , Singer Giselle , Lebwohl Mark G.
Published: March 2003

Background The treatment options for facial and intertriginous skin are limited because these sites are more susceptible to corticosteroid‐induced atrophy. The long‐term management of these corticosteroid‐sensitive sites requires the use of dosing regimens that are effective, but also safe.

Methods The affected areas in 21 patients with atopic dermatitis were treated twice daily for 2 weeks, and then once daily for two consecutive days each week for eight more weeks.

Results After 2 weeks, treatment success occurred in 95% of facial and intertriginous lesions and also in 95% of nonfacial, nonintertriginous lesions. During long‐term therapy, treatment success was maintained in > 76% of facial and intertriginous lesions, and > 76% of other lesions. Recurrence rates were low, and skin atrophy and telangiectasia did not occur.

Conclusions Patients with atopic dermatitis of facial and intertriginous areas were successfully treated with a limited application of fluticasone propionate ointment, 0.005%. The treatment resulted in rapid healing and provided efficacy with a low rate of recurrence and no evidence of skin atrophy or telangiectasia over 8 weeks.
Kaposi's sarcoma in renal transplant patients: experience at the Cruces Hospital in Bilbao
Authors: Mitxelena Josune , Gomez‐Ullate Pablo , Aguirre Antonio , Rubio Gurutze , Lampreabe Ildefonso , Díaz‐Pérez José Luis
Published: March 2003

Background Kaposi's sarcoma (KS) in renal transplant recipients (RTRs) probably arises from a complex interplay of multiple factors.

Objective In order to analyze the prevalence of KS in patients transplanted at the Cruces Hospital in Bilbao, together with their clinical features, treatment, and etiologic factors, we performed a study using the registry of RTRs in our center.

Methods The records of 1230 kidney transplant patients at the Cruces Hospital between 1979 and 1998 were reviewed. Immunosuppressive therapy was reduced once a diagnosis of KS was made. A nested polymerase chain reaction was used to detect human herpesvirus 8 (HHV‐8) DNA in the biopsy tissue. The DNA was extracted from fresh tissue (n = 2) or from formalin‐fixed, paraffin‐embedded specimens (n = 5).

Results Six cases of KS were diagnosed. All patients with cutaneous KS improved with a reduction in immunosuppressive drugs. HHV‐8 was detected in 100% (2/2) of the frozen biopsies and 20% (1/5) of the formalin‐fixed samples investigated.

Conclusions Our experience indicates that a continuous state of immunodeficiency is important for the development of KS in RTRs. The association, previously described between HHV‐8 and transplant‐associated KS, also exists in the studied population.
Mass-to-light ratios from the fundamental plane of spiral galaxy discs
Authors: Graham Alister W.
Published: March 2003

The best-fitting two-dimensional plane within the three-dimensional space of spiral galaxy disc observables (rotational velocity υrot, central disc surface brightness μ0=-2.5 log I0 and disc scalelength h) has been constructed. Applying the three-dimensional bisector method of regression analysis to a sample of ∼100 spiral galaxy discs that span more than 4 mag arcsec−2 in central disc surface brightness yields (B band) and (R band). Contrary to popular belief, these results suggest that in the B band, the dynamical mass-to-light ratio (within four disc scalelengths) is largely independent of the surface brightness, varying as . Consistent results were obtained when the range of the analysis was truncated by excluding the low-surface-brightness galaxies. Previous claims that M/LBvaries withare shown to be misleading and/or caused by galaxy selection effects – not all low-surface-brightness disc galaxies are dark matter dominated. The situation is, however, different in the near-infrared where LK′∝υ4 and M/LK′ is shown to vary as . Theoretical studies of spiral galaxy discs should therefore not assume a constant M/L ratio within any given passband.

The B-band dynamical mass-to-light ratio (within four disc scalelengths) has no obvious correlation with (B-R) disc colour, while in the K′ band it varies as -1.25±0.28(B-R). Combining the present observational data with recent galaxy model predictions implies that the logarithm of the stellar-to-dynamical mass ratio is not a constant value, but increases as discs become redder, varying as 1.70±0.28(B-R).
Mitochondrial DNA variation and the evolutionary history of chromosome races of collared lemmings (Dicrostonyx) in the Eurasian Arctic
Authors: Fedorov  , Fredga  , Jarrell
Published: March 2003

Collared lemmings (Dicrostonyx) demonstrate extensive chromosome variation along their circumpolar distribution in the high Arctic. To reveal the history of this genus and the origin of chromosome races in the Palearctic, we studied the geographical pattern of mtDNA variation in lemmings from 13 localities by using eight tetranucleotide restriction enzymes. The main split in mtDNA phylogeny is at the Bering Strait and corresponds to the main chromosome division between the Beringian and the Eurasian groups of karyotypes. Nucleotide divergence estimate of 6.8% suggests that, despite the Bering Land Bridge, Palearctic and Nearctic forms have been separated since the mid-Pleistocene. Five distinct phylogenetic groups of mtDNA haplotypes, with average divergence of 1.5%, corresponding to geographical regions, were found along the Palearctic coast. Low nucleotide and haplotype diversity and a star-like phylogeny within phylogeographical groups of haplotypes suggest regional bottleneck events in the recent past, most probably due to warming events during the Holocene. There is congruence between phylogeographical pattern of mtDNA variation and geographical distribution of chromosome races; 69% of the total mtDNA variation is allocated among chromosome races. This congruence implies that historical events such as fragmentation and allopatric bottleneck events have been important for the origin of chromosome races. However, historical factors do not explain the fixed autosome fusions found to distinguish certain populations.
Egg-laying reptiles in cold climates: determinants and consequences of nest temperatures in montane lizards
Authors: Shine R.
Published: March 2003

Studies on reptilian life-history evolution have emphasized the role of cold climates as a selective force for the evolution of viviparity, but have tended to neglect the many cold-climate reptiles that retain oviparity. Many of these species avoid low incubation temperatures by selecting warm nest-sites, and the evolution of viviparity (by uterine retention and maternal thermoregulation) is an extension of this strategy. However, an alternative pathway exists: reptiles may adapt to low-temperature incubation rather than avoid it. The scincid lizard Nannoscincus maccoyi from high-elevation areas of south-eastern Australia follows this alternative strategy. Field studies show that Nannoscincus selects cooler oviposition sites than does the sympatric heliothermic skink Bassiana duperreyi, owing to differences in the type of cover object (log vs. rock), the size of cover object and the depth to which eggs are buried. These interspecific differences in natural incubation regimes are reflected in the responses of laboratory-incubated eggs to incubation temperature. Bassiana eggs tolerate higher temperatures than do Nannoscincus eggs, but do not develop as rapidly at low temperatures. Incubation at lower temperatures produces a larger, faster hatchling in Nannoscincus, whereas the reverse is true in Bassiana. Thus, Nannoscincus and Bassiana follow different pathways to overcome the difficulties of reproducing in cold climates. Only the Bassiana pathway is likely to be compatible with the evolution of viviparity.
Parentage analysis in Chamaelirium luteum (L.) Gray (Liliaceae): why do some males have higher reproductive contributions?
Authors: Smouse  , Meagher  , Kobak
Published: March 2003

Much of the contemporary study of adaptation in natural populations involves the regression of some component of fitness, usually survivorship or viability, on one or more characters of interest. It is difficult to apply this approach to measures of paternal reproduction, however, because paternity is typically estimated indirectly from genetic markers, rather than being measured directly from progeny counts. Here, we present maximum likelihood methods for modelling relative male reproductive success as a log-linear function of one or more potentially predictive features, as well as providing a framework for the assessment of pairwise (male:female) effects, as they affect male reproductive performance. We also provide nonparametric statistical tests for alternative models.

Using this formulation, we examine the impact of inflorescence morphology on male reproductive success in Chamaelirium luteum L., and we also assess the importance of intermate distances between males and particular females. While male reproductive success and male inflorescence morphology are both quite variable, reproductive morphology does not appear to predict male reproductive success in this study. Intermate distance is an extremely effective predictor of pairwise success, however; but averaged over females, there is almost no net effect for different males.
What’s wrong with a little sex?
Authors: Peck  , Waxman
Published: March 2003

In many species, most (or all) offspring are produced by sexual means. However, theory suggests that selection should often favour the evolution of species in which a small fraction of offspring are produced sexually, and the rest are produced asexually. Here, we present the analysis of a model that may help to resolve this paradox. We show that, when heterozygote advantage is in force, members of species in which sex is rare will tend to produce poorly adapted offspring when they mate. This problem should be less severe in species where most offspring are produced by sexual means. As a consequence, once the rate of sexual reproduction becomes sufficiently rare, the benefits of sex may vanish, leading to the evolution of obligate asexuality. Substantial benefits of sexual reproduction may tend to accrue only if a large proportion of offspring are produced sexually. We suggest that similar findings are likely in the case of epistatic interactions between loci.
Sex-specific selection and sexual size dimorphism in the waterstrider Aquarius remigis
Authors: Ferguson  , Fairbairn
Published: March 2003

We estimated selection on adult body size for two generations in two populations of Aquarius remigis, as part of a long-term study of the adaptive significance of sexual size dimorphism (SSD). Net adult fitness was estimated from the following components: prereproductive survival, daily reproductive success (mating frequency or fecundity), and reproductive lifespan. Standardized selection gradients were estimated for total length and for thorax, abdomen, genital and mesofemur lengths. Although selection was generally weak and showed significant temporal and spatial heterogeneity, patterns were consistent with SSD. Prereproductive survival was strongly influenced by date of eclosion, but size (thorax and genital lengths in females; total and abdomen lengths in males) played a significant secondary role. Sexual selection favoured smaller males with longer external genitalia in one population. Net adult fitness was not significantly related to body size in females, but was negatively related to size (thorax and total length) in males.
Inbreeding depression by recessive deleterious genes affecting female fecundity of a haplo-diploid mite
Authors: Saito  , Sahara  , Mori
Published: March 2003

The effect of inbreeding on haplo-diploid organisms has been regarded as very low, because deleterious recessive genes on hemizygous (haploid) males were immediately purged generation by generation. However, we determined such recessive genes to decrease female fecundity in a population of Schizotetranychus miscanthi Saito which is known in the Acari as a subsocial species with haplo-diploidy. In mother–son inbreeding experiments, there was no depression in egg hatchability nor in the larval survival of progeny over four generations. There was, on the other hand, significant inbreeding depression in the fecundity with increasing f-value. Crosses between two lineages, one having deleterious effects on the fecundity and the other having no such effects, established during the inbreeding, revealed heterosis, and backcrosses showed that the depression was caused by deleterious recessive(s). These results strongly suggest the existence of some deleterious genes governing only the traits of adult females in wild populations of haplo-diploid organisms.
The influence of self-fertilization and grouping on fitness attributes in the freshwater snail Physa acuta: population and individual inbreeding depression
Authors: Jarne  , Perdieu  , Pernot  , Delay  , David
Published: March 2003

The genetic structure, selfing rate and inbreeding depression of the hermaphroditic freshwater snail Physa acuta were jointly analysed in a population near Montpellier, France. Allozymic markers revealed moderate gene diversity (0.138), and no heterozygote deficiency. The mean outcrossing rate, estimated by using progeny arrays, was 0.9, with substantial variation among families. This also suggests that the number of fathers among outcrossed offspring of a given mother is low. Inbreeding depression was estimated over more than one generation using 83 first-laboratory-generation (G1) families. The main parameters measured were parental (G1) fecundity, offspring (G2) survival and fecundity. Size and growth were also monitored. Parental fecundity was analysed under several conditions (isolation, pair and quadruplet outcrossing). The self-fertilization depression, including parental fecundity, offspring survival and fecundity, was about 0.9 at the population level. The genetic data obtained in the same population indicate a value of about 0.3 using Ritland’s (1990) technique, suggesting that the depression over the whole life-cyle might be even higher than 0.9. Grouping affected neither fecundity nor self-fertilization depression. Substantial variation in depression for survival was detected among individuals, from no survival in some selfed families to better survival than that of outbred families in others. The overall result (outbred population structure, high outcrossing rate and high self-fertilization depression) is consistent with what is expected in large outcrossing populations in which inbreeding depression is maintained by mutation-selection balance.
Fitness effects of a photosynthetic mutation across contrasting environments
Authors: Arntz  , Delucia  , Jordan
Published: March 2003

To test the hypothesis that variation in photosynthesis can cause differences in fitness, we compared wild-type (WT) Amaranthus hybridus genotypes to those having a single-gene mutation (R) that affects photosynthetic rate. By using light and water treatments, we generated a range of differences between WT and R genotypes in photosynthetic rate, growth and reproduction at three developmental stages. In two cases photosynthetic differences were in the expected direction (WT > R), they did not differ in others, and in one case the R genotype had a higher rate than the WT. Across light and water treatments, higher rates of photosynthesis were related to increases in specific leaf area, leaf nitrogen content and stomatal conductance relative to the other genotype. Differences between genotypes in growth and allocation paralleled those in photosynthesis; in treatments where photosynthetic rate differed between the genotypes (high light), growth and reproduction did as well. In high light, the effects of genotype on fitness were indirect with high-water availability, but were direct with low-water availability. When photosynthetic rate did not differ between genotypes (low light), neither did growth and reproduction. These results demonstrate that variation in photosynthesis can cause differences in growth and reproduction. Furthermore, resource availability can moderate the ways in which selection operates on photosynthetic traits.
Developmental stability in yellow dung flies (Scathophaga stercoraria): fluctuating asymmetry, heterozygosity and environmental stress
Authors: Hosken D. J. , Blanckenhorn W. U. , Ward P. I.
Published: March 2003

The genetic basis for developmental stability, the ability of an organism to withstand genetic and environmental disturbance of development, is poorly understood. Fluctuating asymmetry (FA: small random deviations from symmetry in paired, bilateral traits) is the most widely used measure of developmental stability, and evidence suggests FA is weakly and negatively associated with genome-wide heterozygosity. We investigated the genetic basis of developmental stability in the yellow dung fly. Fly lines were inbred for 16 generations at which time they were homozygous at the phosphoglucomutase (PGM) loci and PGM appears to influence FA in at least one other taxon. After 16 generations of inbreeding, lines homozygous for different PGM alleles were crossed and levels of FA for four metric traits were compared in the inbred and crossed flies. We also compared FA levels in these flies with previously gathered data on wild-type (second generation outcrossed) flies, and additionally looked at the effects of two environmental stresses (larval food limitation and increased temperature) on FA. There were no significant differences in any measure of FA, nor in mean FA, in any trait when inbred and crossed flies were compared. Comparison of FA in these and wild flies also revealed no significant differences. Food limitation had no influence on FA, whereas heat stress increased FA of naturally, but not sexually, selected traits. Our results do not show a negative relationship between heterozygosity and FA, but support the notion that FA levels are stress, trait and taxon specific.
Relative fitness of two hermaphroditic mating types in the androdioecious clam shrimp, Eulimnadia texana
Authors: Weeks S. C. , Crosser B. R. , Gray M. M.
Published: March 2003

Androdioecy (populations of males and hermaphrodites) is a rare reproductive form, being described from only a handful of plants and animals. One of these is the shrimp Eulimnadia texana, which has populations comprised of three mating types: two hermaphroditic types (monogenics and amphigenics) and males. In a recent study, the amphigenic hermaphrodites were found to be in greater abundance than that predicted from a model of this mating system. Herein, we compare the relative fitness of offspring from amphigenic and monogenic siblings, attempting to understand the greater relative abundance of the former. Populations started with offspring from selfed monogenic hermaphrodites had a net reproductive rate (R) 87% that of offspring from their amphigenic siblings. Additionally, within populations of amphigenic offspring (which included males, monogenics and amphigenics), amphigenics survived longer than monogenics. These differences help to explain the increased relative abundance of amphigenics in natural populations, but amphigenics continue to be more abundant than expected.
Temperature dependence of development rate and adult size in Drosophila species: biophysical parameters
Authors: Gibert P. , De Jong G.
Published: March 2003

Adult size in Drosophila results from the ratio of the rate of biomass increase and the rate of differentiation, both rates being temperature sensitive. Data on rates and size are collected in two tropical and two temperate Drosophila species; differentiation rate is higher in the two tropical species, growth rate differs between the large and small species of similar climatic origin. A biophysical model is used to evaluate the temperature dependence of adult size in Drosophila. The model is based upon the Sharpe–Schoolfield equation connecting enzyme kinetics and biological rates. Temperature sensitivities of growth rate, development time, and wing and thorax size are characterized by biophysical parameters. The biophysical parameter indicating trait specific temperature sensitivity is lower in tropical species than in temperate species, both for growth rate and for differentiation rate. In the larger species of a climate pair, thorax size and wing size prove to differ in pattern of temperature dependence; in the smaller species of a geographical pair, thorax size and wing size have identical patterns of temperature dependence.
Male-biased gene flow across an avian hybrid zone: evidence from mitochondrial and microsatellite DNA
Authors: Helbig A. J. , Salomon M. , Bensch S. , Seibold I.
Published: March 2003

Mating pattern and gene flow were studied in the contact zone between two morphologically very similar Chiffchaff taxa (Phylloscopus collybita, P. brehmii) in SW France and northern Spain. Mating was assortative in brehmii, but not in collybita. Mixed matings were strongly asymmetric (excess of collybita male × brehmii female pairs), but did produce viable offspring in some cases. Sequence divergence of the mitochondrial cytochrome b gene was 4.6%. Haplotypes segregated significantly with phenotype (only five ‘mismatches’ among 94 individuals), demonstrating that mitochondrial gene flow was very restricted. The estimated proportion of F1 hybrids in the reproductive population was significantly lower than expected under a closed population model, indicating strong selection against hybrids. Genetic typing of 101 individuals at four microsatellite loci also showed significant population differentiation, but nuclear gene flow was estimated to be 75 times higher than mitochondrial gene flow. This strong discrepancy is probably due to unisexual hybrid sterility (Haldane’s rule). Thus, there is a strong, but incomplete, reproductive barrier between these taxa.
Shade avoidance syndrome in Picea omorika seedlings: a growth-room experiment
Authors: Tucić B. , Stojković B.
Published: March 2003

The adaptiveness of shade avoidance responses to density was studied in Picea omorika seedlings raised in a growth-room. Siblings of a synthetic population comprising 117 families from six natural populations were exposed to contrasting density conditions in order to score variation in phenotypic expression of several epicotyl and bud traits included in the shade avoidance syndrome. As predicted for the adaptive plasticity to foliage shade, epicotyl elongation traits tended toward higher, while axillary bud traits toward lower values in high-density vs. low-density conditions. Phenotypic selection analysis revealed that the elongated plants had greater relative fitness than the suppressed ones in both density treatments which could be ascribed to the effect of direct selection on epicotyl length. There was no evidence for plasticity costs associated with the expression of the shade avoidance phenotype either under low or under high density, with only a single exception. Estimates of variance component genetic correlations across densities were significantly different from unity for the majority of the seedling traits studied, indicating the existence of heritable variation within reaction norms of these traits. However, since all these correlations were positive in sign and large in magnitude, this conclusively means that the level of the additive genetic variation for plasticity in the shade-avoidance traits of P. omorika is rather low.
Shifting clinal patterns and microsatellite variation in Drosophila serrata populations: a comparison of populations near the southern border of the species range
Authors: Magiafoglou A. , Carew M. E. , Hoffmann A. A.
Published: March 2003

Geographical patterns for quantitative traits in Drosophila and other insects are commonly used to investigate climatic selection. They are usually determined from comparisons of populations over extensive areas and based on one collection per population. Here we consider patterns in the Australian endemic species Drosophila serrata established over a shorter transect with repeated sampling. Summer (prewinter) and spring (post-winter) collections were made from 10 to 14 localities, incorporating the southern border of D.serrata and extending approximately 1000 km northwards along the eastern coast of Australia. Linear or curvilinear associations with latitude were evident for development time, viability and cold resistance but patterns differed between collections. Some geographical (population) and genetic associations between traits were found and these also tended to differ between collections. Results confirm the importance of cold stress resistance over winter to the southern border of this species. Microsatellite markers were developed for D.serrata. These indicated a low level of genetic differentiation between populations, high levels of gene flow and no evidence that the most southerly populations were isolated. The results suggest that selection generated geographical patterns in cold resistance, development time and viability, and that substantial gene flow may prevent adaptation at the border to conditions beyond the current distribution of D. serrata.
Status-dependence and morphological trade-offs in the expression of a sexually selected character in the mite, Sancassania berlesei
Authors: Radwan J. , Unrug J. , Tomkins J. L.
Published: March 2003

In the male dimorphic mite Sancassania berlesei, fighter males kill rivals with a pair of armoured legs whereas scrambler males are benign with unmodified legs. In an adaptive response mediated by colony pheromones, fighter expression increases at low colony density. Under the status-dependent evolutionarily stable strategy (ESS) model we expected heavier final instar nymphs to become fighters. This was supported in group reared nymphs. In individually reared nymphs fighter expression was experimentally suppressed using two concentrations of colony pheromone. Here, male morph expression again depended on tritonymphal body mass and contact is therefore unnecessary for individuals to judge their status. Fighter suppression was greater in the higher pheromone treatment, but morph determination remained status dependent. The weight and length of fighters was lower than scramblers of same-weight final instar nymphs, indicating a developmental trade-off, and a cost not recouped at the adult stage.
Optimal growth strategies of larval helminths in their intermediate hosts
Authors: Parker G. A. , Chubb J. C. , Roberts G. N. , Michaud M. , Milinski M.
Published: March 2003

We consider optimal growth of larval stages in complex parasite life cycles where there is no constraint because of host immune responses. Our model predicts an individual's asymptotic size in its intermediate host, with and without competition from conspecific larvae. We match observed variations in larval growth patterns in pseudophyllid cestodes with theoretical predictions of our model. If survival of the host is vital for transmission, larvae should reduce asymptotic size as intensity increases, to avoid killing the host. The life history strategy (LHS) model predicts a size reduction <1/intensity, thus increasing the parasite burden on the host. We discuss whether body size of competing parasites is an evolved LHS or simply reflects resource constraints (RC) on growth fixed by the host, leading to a constant total burden with intensity. Growth under competition appears comparable with “the tragedy of the commons”, much analysed in social sciences. Our LHS prediction suggests that evolution generates a solution that seems cooperative but is actually selfish.
Spatial and demographic population genetic structure in Catasetum viridiflavum across a human-disturbed habitat
Authors: Murren C. J.
Published: March 2003

Spatial and temporal genetic structures were examined across sites on islands and mainland (continuous forest) populations of an epiphytic orchid, Catasetum viridiflavum, using 17 polymorphic allozyme loci. I tested whether patches on islands or at mainland sites comprised small local populations or a large population. Low among population differentiation was observed across the landscape suggesting that the species-specific pollinator and tiny wind-dispersed seeds maintain interconnections among distant patches. Temporal genetic structure among stage classes, and among breeding individuals are important components of the maintenance of genetic variation in this orchid. The natural history of this species including small breeding populations, probable high frequency of mating among relatives, and the high rates of seed movement among sites contribute to the high FIS. These data show that physically isolated patches in this epiphytic orchid comprise a single larger genetic population, which is independent of the physical distances among sites. Although quite different in ecological and life history characteristics, the genetic structure of this orchid demonstrates a pattern similar to temperate and tropical trees in fragmented landscapes.