bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of nutrient availability on primary sexual traits and their response to selection in Spergularia marina (Caryophyllaceae)
Authors: Mazer S. J. , Lowry D. E. , Hansen T.
Published: June 2003

Theoretical models of the evolution of sex allocation generally assume a negative genetic correlation between components of male and female investment or function. To test this assumption, and to determine whether the expression of the correlation is sensitive to environmental conditions, we conducted an artificial selection experiment targeting primary sexual traits in the autogamous herb, Spergularia marina. Mass selection favouring individuals with high (or low) pollen and ovule production per flower had previously been conducted for two generations under uniform conditions. Following a third episode of selection (reported here) within the high-pollen-, high-ovule-, low-pollen- and low-ovule-producing lineages, selected maternal seed families were replicated and cultivated in three nutrient treatments. With this design, we observed the effects of nutrient availability on: floral phenotype, the realized response to selection and the expression of genetic variation in, and covariation between, male and female investment. The first two episodes of selection Mazer et al. 1999 (Evolution 53:717–731) detected evidence for a genetically based negative correlation between ovule and anther production. Following the third episode of selection, phenotypic differences among the selected lines were maintained in all treatments, but evidence for a negative correlation between male and female investment nearly disappeared. Only under low-nutrient conditions, in which plants selected for low ovule production exhibited elevated anther production, was a genetic trade-off expressed. Either genetic drift or the combination of novel growing conditions (relative to previous generations) and G × E interactions may have caused the change in the expression of the genetic correlation. This experiment also allowed us to test the prediction that autogamous selfers should exhibit higher canalization of the ratio of male to female investment than of its components. Supporting this prediction, the A : O ratio was more strongly buffered against environmental variation than either anther or ovule production per flower.
Overwintering in Drosophila melanogaster: outdoor field cage experiments on clinal and laboratory selected populations help to elucidate traits under selection
Authors: Hoffmann A. A. , Scott M. , Partridge L. , Hallas R.
Published: June 2003

Insects can adapt to temperate environments by increasing levels of resistance to cold conditions over winter and/or altering reproductive patterns to focus reproduction in favourable conditions. In temperate areas, Drosophila melanogaster persists over winter at the adult stage. A previous experiment, conducted with flies kept in outdoor population cages in the temperate winter, indicated that temperate populations produced more eggs than did tropical populations following an abrupt increase in reproduction in late winter. In contrast, the tropical populations produced more eggs prior to the increase. Both patterns resulted in a higher net number of surviving offspring for temperate populations. Here we again examine the clinal pattern in reproduction using outdoor cages, this time held under tropical winter conditions. In this environment, surprisingly, egg production was higher and on average earlier in populations originating from temperate areas. However, mortality rates also increased with latitude of origin, and the relationship of lifetime egg production to latitude should therefore be measured. To test the role of altered pattern of egg production per se in the reproductive advantage of temperate populations in the temperate winter, we tested the performance of laboratory lines selected for altered reproductive patterns, under temperate winter conditions. Lines selected for high early fecundity exhibited this characteristic in the field cages and lines selected for late reproduction exhibited a relatively high fecundity in spring. The timing of the abrupt increase in egg production was identical in these sets of lines and occurred at the same time in recently collected populations, suggesting evolutionary conservation of the switch. These findings suggest that changes in early and late reproduction per se determine adaptation to temperate winter conditions, and illustrate how laboratory selection lines can be used to understand traits underlying adaptive shifts in field performance.
Ecology, life history and resource allocation in the ant, Leptothorax nylanderi
Authors: Foitzik S. , Strätz M. , Heinze J.
Published: June 2003

We aimed at identifying the causal basis of previously shown interrelations between demographic and genetic colony structure, ecological factors and split sex ratios in the ant, Leptothorax nylanderi. Colony-level variation in sex allocation was only partly explained by annual fluctuations during eight study years and by resource availability as indicated by sexual production of colonies. Allocation ratios were highly male-biased in dense populations with ephemeral nest sites and high frequencies of colonies containing several unrelated matrilines. Field observations and experimental manipulations showed that nest site limitation leads to such heterogeneous colonies. Laboratory experiments demonstrated that genetic heterogeneity directly causes male-biased investment, although relatedness asymmetry is not influenced by invasion of unrelated queens. The influence of genetic composition on allocation strategies might either be explained by negative feedback mechanisms connected with habitat saturation or by a lower efficiency of heterogeneous colonies. Our results thus demonstrate which factors other than variation in relatedness asymmetry can explain split sex ratios in ants. An empirical test of a model on reproductive allocation revealed on-going queen–worker conflict over colony growth and sexual reproduction. Workers controlled reproductive allocation, but queen–worker conflict ceased in large colonies with a high survival rate.
Phenotypic variation in growth trajectories in the Arctic charr Salvelinus alpinus
Authors: Björklund M. , Hirvonen H. , Seppä T. , Peuhkuri N. , Piironen J.
Published: June 2003

Animals with determinate growth have shown little variation in individual growth patterns, but similar analyses for animals with indeterminate growth have been lacking. We analysed the amount of phenotypic variation in growth patterns across ages among individuals of a hatchery-based population of Arctic charr, Salvelinus alpinus, Salmonidae, using the infinite-dimensional model and including the effects of group size structure. There was little phenotypic variation in growth trajectories: individuals that were small (in relation to the mean) early in life were among the smallest 2.5 years later. If the genetic variation reflects phenotypic variation, not much evolutionary change can be expected. Our results show that there are ecological conditions that determine the strong covariation of size across ages, most likely size-related dominance behaviour, which can mask the true variation of growth patterns. Thus, social interactions can have strong evolutionary effects on traits not directly involved in the behavioural interactions.
The evolution of trade-offs: geographic variation in call duration and flight ability in the sand cricket, Gryllus firmus
Authors: Roff D. A. , Crnokrak P , Fairbairn D. J.
Published: June 2003

Quantitative genetic theory assumes that trade-offs are best represented by bivariate normal distributions. This theory predicts that selection will shift the trade-off function itself and not just move the mean trait values along a fixed trade-off line, as is generally assumed in optimality models. As a consequence, quantitative genetic theory predicts that the trade-off function will vary among populations in which at least one of the component traits itself varies. This prediction is tested using the trade-off between call duration and flight capability, as indexed by the mass of the dorsolateral flight muscles, in the macropterous morph of the sand cricket. We use four different populations of crickets that vary in the proportion of macropterous males (Lab = 33%, Florida = 29%, Bermuda = 72%, South Carolina = 80%). We find, as predicted, that there is significant variation in the intercept of the trade-off function but not the slope, supporting the hypothesis that trade-off functions are better represented as bivariate normal distributions rather than single lines. We also test the prediction from a quantitative genetical model of the evolution of wing dimorphism that the mean call duration of macropterous males will increase with the percentage of macropterous males in the population. This prediction is also supported. Finally, we estimate the probability of a macropterous male attracting a female, P, as a function of the relative time spent calling (P = time spent calling by macropterous male/(total time spent calling by both micropterous and macropterous male). We find that in the Lab and Florida populations the probability of a female selecting the macropterous male is equal to P, indicating that preference is due simply to relative call duration. But in the Bermuda and South Carolina populations the probability of a female selecting a macropterous male is less than P, indicating a preference for the micropterous male even after differences in call duration are accounted for.
Opposites attract? Mate choice for parasite evasion and the evolutionary stability of sex
Authors: Howard R. S. , Lively C. M.
Published: June 2003

If sex is naturally selected as a way to combat parasites, then sexual selection for disease resistance might increase the overall strength of selection for outcrossing. In the present study, we compared how two forms of mate choice affect the evolutionary stability of outcrossing in simultaneous hermaphrodites. In the first form, individuals preferred to mate with uninfected individuals (condition-dependent choice). In the second form, individuals preferred to mate with individuals that shared the least number of alleles in common at disease-resistance loci. The comparisons were made using individual-based computer simulations in which we varied parasite virulence, parasite transmission rate, and the rate of deleterious mutation at 500 viability loci. We found that alleles controlling both forms of mate choice spread when rare, but their effects on the evolutionary stability of sex were markedly different. Surprisingly, condition-dependent choice for uninfected mates had little effect on the evolutionary stability of sexual reproduction. In contrast, active choice for mates having different alleles at disease-resistance loci had a pronounced positive effect, especially under low rates of deleterious mutation. Based on these results, we suggest that mate choice that increases the genetic diversity of offspring can spread when rare in a randomly mating population, and, as an indirect consequence, increase the range of conditions under which sexual reproduction is evolutionarily stable.
The evolution of polyandry: patterns of genotypic variation in female mating frequency, male fertilization success and a test of the sexy-sperm hypothesis
Authors: Simmons L. W.
Published: June 2003

The sexy-sperm hypothesis predicts that females obtain indirect benefits for their offspring via polyandy, in the form of increased fertilization success for their sons. I use a quantitative genetic approach to test the sexy-sperm hypothesis using the field cricket Teleogryllus oceanicus. Previous studies of this species have shown considerable phenotypic variation in fertilization success when two or more males compete. There were high broad-sense heritabilities for both paternity and polyandry. Patterns of genotypic variance were consistent with X-linked inheritance and/or maternal effects on these traits. The genetic architecture therefore precludes the evolution of polyandry via a sexy-sperm process. Thus the positive genetic correlation between paternity in sons and polyandry in daughters predicted by the sexy-sperm hypothesis was absent. There was significant heritable variation in the investment by females in ovaries and by males in the accessory gland. Surprisingly there was a very strong genetic correlation between these two traits. The significance of this genetic correlation for the coevolution of male seminal products and polyandry is discussed.
A phylogenetic approach to assessing the targets of microbial warfare
Authors: Riley M. A. , Goldstone C. M. , Wertz J. E. , Gordon D.
Published: June 2003

Bacteriocins are the most abundant and diverse defense systems in bacteria. As a result of the specific mechanisms of bacteriocin recognition and translocation into the target cell it is assumed that these toxins mediate intra-specific or population-level interactions. However, no published studies specifically address this question. We present here a survey of bacteriocin production in a collection of enteric bacteria isolated from wild mammals in Australia. A subset of the bacteriocin-producing strains was assayed for the ability to kill a broad range of enteric bacteria from the same bacterial collection. A novel method of estimating killing breadth was developed and used to compare the surveyed bacteriocins in terms of the phylogenetic range over which they kill. The most striking result is that although bacteriocin-producers kill members of their own species most frequently, some kill phylogenetically distant taxa more frequently than they kill closer relatives. This study calls into question the role these toxins play in natural populations. A significant number of bacteriocins are highly effective in killing inter-specific strains and thus bacteriocins may serve to mediate bacterial community interactions.
Phenotypic analysis of peripheral T/NK cell lymphoma: Study of 408 Japanese cases with special reference to their anatomical sites
Authors: Ichimura Koichi , Kagami Yoshitoyo , Suzuki Ritsuro , Kojima Masaru , Yoshino Tadashi , Ohshima Koichi , Koike Koichi , Kondo Eisei , Taji Hirofumi , Ogura Michinori , Morishima Yasuo , Akagi Tadaatsu , Takahashi Toshitada , Nakamura Shigeo
Published: June 2003

The World Health Organization (WHO) classification of malignant lymphoma presented a list of disease entities well defined by clinical, immunological and genetic features. Therefore, the current diagnosis of peripheral T/NK‐cell lymphomas (PTNKLs) essentially requires the inclusion of anatomical sites of disease and phenotypical features. We analyzed 408 Japanese cases of PTNKLs in order to clarify the relationship between anatomical sites of disease and phenotypical features and to translate the functional subsets of T and NK cells into their diagnoses for further understanding lymphomatic biology. The T/NK‐cell lymphoma entities were allocated into three categories: (i) cytotoxic memory T‐cell and/or NK‐cell lymphoma (n = 151) consisting of extranodal NK/T‐cell tumors other than mycosis fungoides (MF); (ii) non‐cytotoxic memory T‐cell lymphoma (n = 142) consisting of nodal and cutaneous tumors such as angioimmunoblastic T‐cell lymphoma, adult T‐cell lymphoma/leukemia and MF; and (iii) anaplastic lymphoma kinase positive anaplastic large cell lymphoma (n = 110) that has unique features and might be regarded as cytotoxic ‘naive’ T‐cell lymphoma. Overall, these three categories were significantly correlated with age of onset, anatomical sites, the level of expression of cytotoxic molecules and CD45RO, and association with Epstein–Barr virus. This concept might provide a new insight enabling further understanding of the interrelationships among WHO T/NK‐cell disease entities.
Peculiar form of cerebral microdysgenesis characterized by white matter neurons with perineuronal and perivascular glial satellitosis: A study using a variety of human autopsied brains
Authors: Arai Nobutaka , Umitsu Reiko , Komori Takashi , Hayashi Masaharu , Kurata Kiyoko , Nagata Jinro , Tamagawa Kimiko , Mizutani Toshio , Oda Masaya , Morimatsu Yoshio
Published: June 2003

Microdysgenesis (MD) is a neuropathological term that implies a variety of minor developmental abnormalities of the brain. Recently, MD has been used for pathological diagnosis of cerebral tissues surgically resected from epileptic patients. However, criteria or consensus on pathological diagnosis of MD is still vague and controversial because of the lack of control studies. Therefore, this study paid special attention to the presence of white matter neurons with perineuronal glial satellitosis (WMN‐GS) and perivascular glial satellitosis (PVGS) in the white matter, which are occasionally observed in epileptic foci, in order to clarify whether they could be handled as definite findings of MD. The materials included 80 autopsied whole brains ranging from normal subjects to patients with cerebrovascular disorder, neurodegenerative diseases and malformations. In each case, the presence of WMN‐GS and/or PVGS was searched in 10 gyri in all five lobes (rostral frontal lobe, caudal frontal lobe, parietal lobe, temporal lobe and oc‐cipital lobe) and evaluated. Statistically significant, WMN‐GS and/or PVGS preferentially appeared in a diseased group consisting of neuronal migration disorder and related conditions, such as polymicrogyria, nodular heterotopia or tuberous sclerosis, leading to a suggestive conclusion that the presence of WMN‐GS and/or PVGS could be a peculiar form of MD possibly derived from neuronal migrational arrest or related events, even if they appear alone without any other gross abnormalities.
Immunohistochemical demonstration of 14‐3‐3 sigma protein in normal human tissues and lung cancers, and the preponderance of its strong expression in epithelial cells of squamous cell lineage
Authors: Nakajima Takashi , Shimooka Hanako , Weixa Peng , Segawa Atsuki , Motegi Atsushi , Jian Zhang , Masuda Norihiko , Ide Munenori , Sano Takaaki , Oyama Tetsunari , Tsukagoshi Hiroe , Hamanaka Kozue , Maeda Masahiro
Published: June 2003

In order to confirm 14‐3‐3 sigma (σ) protein distribution in human tissues, immunohistochemistry was performed using various paraffin‐embedded human tissues. In normal human tissues, the strongest immunoreactivity for 14‐3‐3σ protein was observed in squamous epithelia at various sites, followed by basal cells of the trachea, bronchus and basal or myoepithelial cells of various glands. Moderate to weak 14‐3‐3σ immunoreactivity was seen in the epithelial cells of the alimentary tract, gall bladder, urinary tract and endometrium. In the lung, 14‐3‐3σ immunoreactivity was also observed in hyperplastic type II alveolar cells and metaplastic squamous cells. Immunohistochemical study using non‐small‐cell lung cancers revealed that 14‐3‐3σ immunoreactivity was stronger in squamous cell carcinomas than in adenocarcinomas. The present study revealed that 14‐3‐3σ expression was exclusively present in various epithelial cells and had a tendency to be stronger in cells destined for squamous epithelium or differentiating toward squamous cells in human normal and neoplastic cells.
Usefulness of endoscopic biopsy using immunostaining of p53 and Ki‐67 in tumors of the ampulla of Vater
Authors: Kubota Kensuke , Kakuta Yukio , Kawamura Shunji , Saito Shuichi , Seki Hideichi , Kuniyoshi Takashi
Published: June 2003

We investigated the diagnostic and prognostic value of p53 expression and proliferative activity, as indicated by the Ki‐67, in endoscopic biopsy specimens. Specimens were immunologically stained with p53 and MIB‐1 (Ki‐67), and the MIB‐1/Ki‐67 labeling index (LI) was calculated. Classification of adenomas was based on findings of H&E‐stained preparations into those with low‐ or high‐grade atypia. Well‐differentiated tubular and papillary adenocarcinomas were classified as carcinomas with low‐ or high‐grade atypia. There were significant differences among the control and adenoma patients in MIB‐1/Ki‐67 LI (P < 0.05). No significant difference was identified between adenomas with high grade atypia and carcinomas with low grade atypia. The p53 expression was negative in all adenomas, but it was positive in 68.2% of carcinomas. The current study demonstrated that p53 protein expression in endoscopic biopsy specimens was of preoperative diagnostic value for carcinoma of the ampulla of Vater. The p53 protein positive tumors had a relatively higher malignant potential than p53 protein negative ones. The MIB‐1/Ki‐67 LI was useful in differentiating non‐tumorous lesions from adenomas and adenomas with low‐ or high‐grade atypia. The MIB‐1/Ki‐67 LI had a prognostic value because clinicopathological factors of carcinoma of ampulla of Vater correlated with MIB‐1/Ki‐67 LI.
Fibrosis and smooth muscle metaplasia in rectovaginal endometriosis
Authors: Itoga Tomoko , Matsumoto Toshiharu , Takeuchi Hiroyuki , Yamasaki Shigetaka , Sasahara Noriko , Hoshi Tanji , Kinoshita Katsuyuki
Published: June 2003

Rectovaginal (RV) endometriosis presents with a nodular lesion composed of fibromuscular and endometriotic tissue, and the fibromuscular tissue is the major component in the severe stage. The purpose of our study was to examine the extending process of fibromuscular tissue in RV endometriosis. Histological examinations using immunostains, were performed in 90 RV tissue specimens from 37 women. Fibrosis was present in 89 specimens. In each specimen, the intensity of the fibrosis differed from area to area: in mildly fibrotic areas, the collagen fibers were present around the endometriotic tissue, and in severely fibrotic areas, the fibrosis widely extended into fat and connective tissus as well as within the endometriotic tissue. In the 60 specimens containing endometriotic tissue, the increase in the amount of endometriotic tissue significantly correlated to the increase in degree of fibrosis in the entire tissue. The presence of aggregated smooth muscles, unassociated with blood vessels, was defined as smooth muscle metaplasia (SMM), which was always present within the fibrotic areas, and was observed in 80 specimens. The degree of SMM in the entire tissue was significantly correlated with the degree of fibrosis. From these findings, the following was hypothesized. Initially, endometriotic tissue was present sporadically and fibrosis was present around the endometriotic tissue. Thereafter, proliferation of endometriotic tissue and an increase in fibrosis occur consecutively. The SMM was present within the fibrotic areas, and it became more severe, correlating with the increase in fibrosis. In conclusion, this is the first report describing the extending process of the fibromuscular tissue of RV endometriosis from a histological viewpoint, and we think that recognization of this process is useful for histological diagnosis and clinical management of RV endometriosis.
Inflammatory myofibroblastic tumor with predominant anaplastic lymphoma kinase‐positive cells lacking a myofibroblastic phenotype
Authors: Hisaoka Masanori , Shimajiri Shohei , Matsuki Yasumasa , Meis‐Kindblom Jeanne M. , Kindblom Lars‐Gunnar , Li Xiao‐Qiu , Wang Jian , Hashimoto Hiroshi
Published: June 2003

Inflammatory myofibroblastic tumor (IMT), synonymously referred to as inflammatory pseudotumor, is a distinctive mesenchymal lesion composed of spindle cells displaying morphological features of myofibroblasts admixed with considerable numbers of inflammatory cells. Recent genetic and molecular studies have shown that a subset of IMT is characterized by the expression of altered anaplastic lymphoma kinase (ALK) protein mostly resulting from rearrangements of the ALK gene such as TPM3‐ALK, TPM4‐ALK and CLTC‐ALK fusion genes. We analyzed the ALK status in nine cases of IMT arising in various anatomical locations. Six cases showed immunohistochemical expression of the ALK protein, and two ALK‐positive lesions examined by reverse transcription‐polymerase chain reaction and a subsequent sequencing analysis harbored the TPM4‐ALK fusion gene. Of note, the majority of ALK‐positive tumor cells in four of the six lesions lacked the coexpression of myogenic markers including α‐smooth muscle actin, a cytoskeletal protein indicating myofibroblastic differentiation, whereas a substantial number of tumor cells in the remaining two cases coexpressed ALK and α‐smooth muscle actin and/or desmin. In an ultrastructural study of the lesion with predominant ALK‐positive/actin‐negative cells, spindle cells failed to demonstrate features of myofibroblasts such as intracytoplasmic bundles of thin filaments and dense bodies. The current findings suggest that ALK‐positive cells in IMT are not always myofibroblastic but might be immature primitive mesenchymal cells.
Ataxia and male sterility (AMS) mouse. A new genetic variant exhibiting degeneration and loss of cerebellar Purkinje cells and spermatic cells
Authors: Harada Takayuki , Pineda Liliam L. , Nakano Akinobu , Omura Koji , Zhou Li , Iijima Masaaki , Yamasaki Yoji , Yokoyama Minesuke
Published: June 2003

We describe a novel genetic variant mouse that exhibited ataxia and male sterility , named the AMS mouse. It arose in autoimmune‐prone MRL/lprstrain and putativeamsmutation showed an autosomal recessive inheritance pattern. Clinical symptoms were first discernible at approximately 21 days of age and consisting of subtle sway of the trunk followed by failure to maintain still posture and appearance of abnormal walk, but no further worsening was noted with advancement of age. The abnormal motor coordination was ascribed to almost complete loss of Purkinje cells of the cerebellum. The cell loss in the Purkinje cell layer began before onset of ataxia and rapidly progressed towards near‐complete loss by 6 weeks of age. Another symptom was male sterility due to severe oligozoospermia associated with cellular degeneration during spermatic differentiation in the seminiferous tubules. Thus, the effects of the genetic variation were apparent in two different organs after the development of their basic histological structures, and degeneration and loss of particular cell types in these two tissues produced overt clinical symptoms. Genetic pleiotropism, provided that the nature of genetic variation is of a single gene mutation, is discussed.
Intra‐epithelial neuroendocrine carcinoma of the nasal cavity
Authors: Watanabe Kazuo , Ogura Go , Suzuki Toshimitsu
Published: June 2003

We describe a distinctive neuroendocrine carcinoma (NEC) that proliferated intra‐epithelially. The tumor was 35 mm in diameter and arose from the right superior turbinate of a 46‐year‐old woman. Histologically, the tumor exhibited papillary growth and the tumor cells were localized in the thickened mucosal epithelium. The tumor cells had round to oval and vesicular or hyperchromatic nuclei, and cohered without any specific structure such as a fibrillary background, rosette or glandular structure. No stromal invasion by the tumor was observed. Immunohistochemically, the tumor cells were positive for neuron‐specific enolase focally. In addition, many tumor cells expressed cytokeratin (AE1/AE3 and CAM 5.2), mostly with characteristic perinuclear dot‐like patterns. Electron microscopy revealed focal but well‐eveloped cytoplasmic processes containing arrays of microtubules and a few dense core granules. The tumor was considered to be a poorly differentiated neuroendocrine carcinomas (NEC) that exhibited exceptional intra‐epithelial proliferation. The tumor completely disappeared after the stereotactic radiosurgery and has not recurred for 40 months. It might be difficult to distinguish a poorly differentiated NEC in the sinonasal region from other neuroectodermal tumors, including olfactory neuroblastoma, but the differential diagnosis is important because each tumor has different clinicopathological characteristics.
Desmoplastic malignant mesothelioma of the pleura: Autopsy reveals asbestos exposure
Authors: Ishikawa Ryoichi , Kikuchi Hidetake , Jin Mulan , Fujita Miri , Itoh Tomoo , Sawa Hirofumi , Nagashima Kazuo
Published: June 2003

Desmoplastic mesothelioma is a rare subtype of diffuse malignant mesothelioma, and is often difficult to distinguish from reactive pleural fibrosis because of associated extensive collagen fibrosis. An 82‐year‐old woman with a severe cough was revealed to have pleural effusion and diffuse pleural thickening on the right side. Antibiotics were ineffective, and a compression fracture of the ninth and tenth thoracic vertebral bodies was recognized on X‐ray. Autopsy revealed a diffuse pleural thickening with hyalinized collagen tissue in the central part of the pleura. However, the peripheral part of the fibrous tissue was composed of spindle and polygonal cell proliferation that were immunohistochemically positive for antibodies against cytokeratin and vimentin. In addition, the ninth and tenth thoracic spines were infiltrated by similar cells. The condition was diagnosed as desmoplastic mesothelioma with bone metastases. Asbestos bodies were detected in the thickened pleura and fibrosed alveolar septa, and it was suggested retrospectively that the patient had been exposed to asbestos. Thus, autopsy analyses of fibrous pleurisy are necessary to detect a desmoplastic variant of mesothelioma of the pleura and its association with asbestos exposure.
Antidepressant and anxiolytic‐like effects in mice lacking the group III metabotropic glutamate receptor mGluR7
Authors: Cryan John F. , Kelly Peter H. , Neijt Hans C. , Sansig Gilles , Flor Peter J. , Van Der Putten Herman
Published: June 2003

Glutamatergic neurotransmission has been strongly implicated in the pathophysiology of affective disorders, such as major depression and anxiety. Of all glutamate receptors, the role of group III metabotropic glutamate receptors (mGluR4, mGluR6, mGluR7, mGluR8) in such disorders is the least investigated because of the lack of specific pharmacological tools. To this end, we examined the behavioural profiles of mice with a targeted deletion of the gene for mGluR7 (mGluR7−/−) in animal models of depression and anxiety. mGluR7−/− mice were compared with wild‐type (mGluR7+/+) littermates and showed substantially less behavioural immobility in both the forced swim test and the tail suspension test. Both behavioural paradigms are widely used to predict antidepressant‐like activity. Further, mGluR7−/− mice displayed anxiolytic activity in four different behavioural tests, i.e. the light–dark box, the elevated plus maze, the staircase test, and the stress‐induced hyperthermia test, while their cognitive performance was normal in the passive avoidance paradigm. Analysis of locomotor activity in a novel environment demonstrated that mGluR7−/− mice were slightly more active in the initial minutes following placement in the chamber only. Together, these data suggest that mGluR7 may play a pivotal role in mechanisms that regulate behavioural responses to aversive states. Therefore, drugs acting at mGluR7 may provide novel treatments for psychiatric disorders such as depression and anxiety.
Molecular biology and electrophysiology of neuronal nicotinic receptors of rat chromaffin cells
Authors: Di Angelantonio Silvia , Matteoni Cosetta , Fabbretti Elsa , Nistri Andrea
Published: June 2003

Neuronal nicotinic acetylcholine receptors of chromaffin cells in the adrenal medulla are physiologically activated by acetylcholine to mediate catecholamine release into the bloodstream. The present study examined the subunit composition and functional properties of rat chromaffin cell neuronal nicotinic acetylcholine receptors using molecular biology, immunocytochemistry and whole‐cell patch‐clamp. Reverse transcription‐polymerase chain reaction analysis indicated the presence of α2, α3, α4, α5, α7, β2 and β4 transcripts (α6 and β3 could not be detected). Immunocytochemistry revealed most cells positive for α3, β2, β4 and α5 proteins. Few cells were immunoreactive for α2 and α4, while none was for α7. At single‐cell level, colocalization could be demonstrated for α3α5 and α4β2. Western blot analysis confirmed antibody specificity for α3, α4, α5, β2 and β4 subunits. Inward currents elicited by nicotine pulses were insensitive to α‐bungarotoxin and low doses of methyllycaconitine, demonstrating lack of functional α7 receptors. Partial block of nicotine currents was observed with either AuIB α‐conotoxin (selective against α3β4 receptors) or MII α‐conotoxin (selective against α3β2 receptors). With high concentrations of co‐applied toxins, antagonism occlusion developed, suggesting loss of subunit selectivity. Antagonism by dihydro‐β‐erythroidine summated nonlinearly with AuIB and MII inhibition, confirming heterogeneity of neuronal nicotinic acetylcholine receptor block. The present results suggest that the most frequently encountered receptors of rat chromaffin cells should comprise α3β4, α3β2 with the addition of α5 subunits. Because of the prevailing subunit composition, rat chromaffin cell neuronal nicotinic acetylcholine receptors are suitable models, particularly for the α3β4 subclasses of mammalian brain receptors recently demonstrated in discrete cerebral areas.
Differential modulation of NMDA‐induced calcium transients by arachidonic acid and nitric oxide in cultured hippocampal neurons
Authors: Richards D. A. , Bliss T. V. P. , Richards C. D.
Published: June 2003

We have examined the effect of arachidonic acid on the transient increases in intracellular Ca2+ evoked by NMDA and AMPA in cultured hippocampal pyramidal cells loaded with Fura‐2 AM. Repeated brief pulses of NMDA elicited Ca2+ transients that showed a modest run down. This run down was enhanced if the preparation was shielded from UV light and was reduced by conducting the experiments in the presence of the nitric oxide synthase inhibitor l‐nitroarginine (100 µm). Arachidonic acid (2 µm) enhanced the Ca2+ transients evoked by NMDA but not those evoked by AMPA. Other C20 unsaturated fatty acids did not alter the time course of the response to NMDA. These experiments suggest that elevated intracellular Ca2+ activates nitric oxide synthase and the resulting synthesis of nitric oxide depresses the Ca2+ response to NMDA while arachidonic acid augments these responses. Therefore two substances implicated in synaptic plasticity (arachidonic acid and nitric oxide) differentially modulate NMDA‐mediated Ca2+ entry into hippocampal neurons.
Laminar differences in plasticity in area 17 following retinal lesions in kittens or adult cats
Authors: Waleszczyk W. J. , Wang C. , Young J. M. , Burke W. , Calford M. B. , Dreher B.
Published: June 2003

Circumscribed retinal lesions in adult cats result in a reorganization of circuitry in area 17 such that neurons in the lesion projection zone (LPZ) can now be activated, not from their original receptive fields (RFs) but from regions of normal retina adjacent to the lesion (‘ectopic’ RFs). We have studied this phenomenon further by making circumscribed monocular retinal lesions in 8‐week‐old kittens and recording responses to visual stimuli of neurons in the LPZ of area 17 when these cats reached adulthood. These responses have been compared with those in adult‐lesioned cats either of relatively short postlesion survival (2–24 weeks) or long postlesion survival (3.5–4.5 years). In both kitten‐lesioned and adult‐lesioned animals most LPZ neurons recorded from the supragranular layers (II and III) not only exhibited new ectopic RFs when stimuli were presented via the lesioned eye but the RF properties (e.g. the sizes of excitatory RFs, orientation and direction selectivities, velocity preferences and upper cut‐off velocities) were often indistinguishable from those seen when stimuli were presented via the nonlesioned eye. Similarly, in both kitten‐lesioned and adult‐lesioned animals, most LPZ neurons recorded from the granular and infragranular layers (IV, V, VI), like those recorded from the supragranular layers, were binocular. However, in adult‐lesioned but not in kitten‐lesioned animals, the responses and the upper cut‐off velocities of LPZ cells recorded from the granular and infragranular layers to stimuli presented via ectopic RFs tended to be, respectively, substantially weaker and lower than those for stimuli presented via the nonlesioned eye. The age‐related laminar differences in reorganizational plasticity of cat striate cortex correlate with the lamino‐temporal pattern of distribution of N‐methyl‐d‐aspartate glutamate receptors in striate cortex.
Involvement of post‐synaptic kainate receptors during synaptic transmission between unitary connections in rat neocortex
Authors: Ali Afia B.
Published: June 2003

The properties of functional kainate receptor‐mediated EPSCs were studied in acute slices from 19–35‐day‐old rats. EPSCs elicited in pyramidal and fast‐spiking cells in layers 2/3 and 5 of the rat motor cortex by extracellular single shock stimulus in the presence of GYKI 53655 and D‐2‐amino‐5‐phosphopentanoic resulted in a residual current. This current was not enhanced by cyclothiazide but was blocked by 6‐cyano‐7‐nitroquinoxalin‐2,3‐dione and is thought to be mediated by kainate receptors. These kainate receptor‐mediated currents displayed a wide range of time courses depending on which pre‐synaptic fibres were activated. With paired recordings, unitary EPSCs elicited in pyramidal cells were almost totally blocked by GYKI 53655 and D‐2‐amino‐5‐phosphopentanoic. However, when L‐transpyrrolidine‐2,4‐dicarboxylate (PDC), a glutamate uptake blocker, was introduced in the bath, the amplitude of kainate receptor‐mediated currents, which is resistant to GYKI 53655 and D‐2‐amino‐5‐phosphopentanoic, was revealed. The rise and decay time constants of the kainate receptor‐mediated currents were identical to control EPSCs. PDC was not required to reveal the kainate receptor‐mediated currents elicited in fast‐spiking cells which also displayed similar rise and decay time constants to the control EPSCs. Excitatory input onto pyramidal and fast‐spiking cells in the neocortex mediated by kainate receptors contributed between 14 and 40% of the total control unitary EPSCs which displayed identical time courses to the AMPA receptor‐mediated component of the EPSCs. Post‐synaptic kainate receptors at connected pyramidal cell synapses may be located extra‐synaptically.
Electrophysiological properties of the utricular primary transducer are modified during development under hypergravity
Authors: Chabbert Christian , Brugeaud Aurore , Lennan Georges , Lehouelleur Jacques , Sans Alain
Published: June 2003

The electrophysiological development of hair cells between birth and the eight postnatal day (P8) was studied in the utricular macula of rats gestated in nest boxes mounted upon a centrifuge, subjecting the animals to a gravitational force of 2G. Whole‐cell voltage‐clamp recordings were made on cells in the acutely isolated epithelium. Cells were accessed through a tear in the epithelium, no enzymatic dissociation procedures were employed. Under artificially enhanced gravity, the whole cell conductance was dramatically altered in the two types of hair cells. Significant increases occurred from P3–4 in the type I cells while in the type II cells, the effect was delayed until P7–8. Fourfold and threefold increases of the mean slope conductance were observed at P7–8 in the type I and type II hair cells, respectively. These results indicate that the electrophysiological properties of a primary transducer such as utricle may be modified by variation of the primary stimulus during development.
Sound presentation rate is represented logarithmically in human cortex
Authors: Sable Jeffrey J. , Gratton Gabriele , Fabiani Monica
Published: June 2003

The encoding of temporal information is critical to auditory processing. Since the mismatch negativity component of the auditory event‐related brain potential is thought to reflect properties of auditory sensory memory, we used it to examine the representation of acoustic time intervals in the human cortex. The mismatch negativity occurs in response to deviations in acoustic regularities, which are stored in sensory memory. We used 16 stimulus conditions, randomly presenting short trains of tones with fixed onset‐to‐onset intervals of 100, 200, 300 or 400 ms (all tones in the study were identical). The first four intervals between the tones established the acoustic regularity on each train (i.e. the ‘standard’). The fifth tone in each train was preceded by an interval that varied randomly among the same four intervals. If this interval was different from the standard for that trial, it violated the acoustic regularity (i.e. it was a ‘deviant’). The mismatch response to the fifth tone differed significantly among stimulus conditions and was proportional to the absolute value of the logarithm of the deviant/standard interval ratio. This indicates that short acoustic time intervals are represented with a ratio scale in the human cortex. When the fifth tone occurred 100 ms after the fourth, it elicited a somewhat different, although proportional response, supporting the hypothesis that a special integration mechanism may exist for very short time intervals.
Molecular characterization of Enterococcus faecalis two‐component signal transduction pathways related to environmental stresses
Authors: Le Breton Yoann , Boël Grégory , Benachour Abdellah , Prévost Hervé , Auffray Yanick , Rincé Alain
Published: June 2003

A key issue in the comprehension of the Enterococcus faecalis stress response is to understand how this bacterium is able to modulate its gene expression in accordance to environmental conditions. Through bio‐informatic analysis of the E. faecalis V583 genome, nine two‐component systems and a single orphan response regulator were identified. A transcriptional study gave evidence of four systems whose expression is induced by at least one environmental stress. In addition, gene disruption experiments allowed the isolation of eight response regulator mutants. Insertional inactivation of the response regulator gene err 05 resulted in growth default and cell morphology alterations; and also in expression default of the sagA gene, this latter being recently shown involved in E.  faecalis stress resistance toward numerous lethal  treatments (Y. Le Breton, A. Mazé, A. Hartke, S. Lemarinier, Y. Auffray and A. Rincé (2002) Current Microbiol 45: 434–439). Disruption of the err 04, err 08 or err 18 genes resulted in sensitivity towards heat. Finally, the err 10 mutant was shown to be more sensitive to acid pH and NaCl whereas its growth was less affected by bile salts or heat. We also demonstrated that the heat resistance phenotype of the err 10 mutant was correlated with an increase of the heat shock proteins DnaK and GroEL level.
Specificity in the settlement – modifying response of bacterial biofilms towards zoospores of the marine alga Enteromorpha
Authors: Patel Pratixa , Callow Maureen E. , Joint Ian , Callow James A.
Published: June 2003

Previous studies have shown that the rate of settlement of zoospores of the green alga Enteromorpha is stimulated by mixed microbial biofilms and that the number of zoospores settling is positively correlated with the number of bacteria in the biofilm. In the present study the specificity of this relationship has been investigated. Ninety‐nine strains of marine bacteria were isolated from natural biofilms on rocks and the surface of Enteromorpha plants. Isolates were screened by denaturing gradient gel electrophoresis (DGGE) to eliminate replicates and 16S rDNA sequencing identified a total of 37 unique strains. Phylogenetic analysis revealed that the isolated bacterial strains belonged to three groups γ‐Proteobacteria (28 strains), Cytophaga‐Flavobacteria‐Bacteroid (CFB) group (six strains) and α‐Proteobacteria (one strain). Two strains were unassigned, showing < 93% sequence similarity with the CFB group. The main genera of γ‐Proteobacteria were Pseudoalteromonas (14 strains), Vibrio (five strains), Shewanella (five strains), Halomonas (three strains) and Pseudomonas (one strain). Spore settlement experiments were conducted on single‐species biofilms, developed for different times on glass slides. The effect of correcting spore settlement values for biofilm density was evaluated. Results showed that the effect of bacterial strains on spore settlement was strain‐ but not taxon‐specific and activity varied with the age of the biofilm. However, most of the strains belonging to genera Vibrio and Shewanella showed stimulation. Pseudoalteromonas strains showed a range of effects including settlement‐inhibiting, paralysing and lysing activities. Spatial analysis of bacterial density in the presence and absence of spores revealed a range of different types of association between spores and bacteria. Overall, the spatial association between spores and bacteria appears to be independent of the overall quantitative influence of bacterial cells on spore settlement.
Characterization of a Vibrio cholerae phage isolated from the coastal water of Peru
Authors: Talledo Miguel , Rivera Irma N. G. , Lipp Erin K. , Neale Angela , Karaolis David , Huq Anwar , R. Colwell Rita
Published: June 2003

A Vibrio cholerae bacteriophage, family Myoviridae, was isolated from seawater collected from the coastal water of Lima, Peru. Genome size was estimated to be 29 kbp. The temperate phage was specific to V. cholerae and infected 12/13 V. cholerae O1 strains and half of the four non‐O1/non‐O139 strains tested in this study. Vibrio cholerae O139 strains were resistant to infection and highest infection rates were obtained in low nutrient media amended with NaCl or prepared using seawater as diluent.
A δ13C‐based carbon flux model for the hydrothermal vent chemoautotrophic symbiosis Riftia pachyptila predicts sizeable CO2 gradients at the host–symbiont interface
Authors: Scott Kathleen M.
Published: June 2003

The chemoautotrophic symbiosis Riftia pachyptila has extremely 13C‐enriched δ13C values. Neither isotopic discrimination by the RubisCO enzyme of their bacterial endosymbionts, nor the δ13C value of CO2 at their hydrothermal vent habitat, suffice to explain biomass δ13C values in this organism, which range from − 9 to − 16‰. However, these 13C‐enriched δ13C values are consistent with the presence of 13C‐enriched CO2 within the symbiont cytoplasm. Such a 13C‐enriched pool of CO2 is expected when the rate of CO2 fixation by RubisCO, which fixes 12CO2 more rapidly than 13CO2, approaches the rate of exchange between intracellular and extracellular CO2 pools. Rapid CO2 fixation rates will also generate concentration gradients between these two pools. In order to estimate the size of these concentration gradients, an equation was derived, which describes the δ13C of tubeworm biomass in terms of the size of the CO2 gradient between the hydrothermal vent environment and the symbiont cytoplasm. Using mass balance equations for CO2 exchange and fixation by the symbionts and the tubeworm host, this model predicts that a CO2 concentration gradient of up to 17‐fold between the symbiont cytoplasm and the environment is sufficient to explain even the most 13C‐enriched R. pachyptila biomass. This model illustrates how both physical and enzymatic factors can act to influence the δ13C of intracellular CO2, which, in turn, highlights the danger of assigning a carbon fixation pathway to an autotroph based solely on its biomass δ13C value.
Bacterial recovery from ancient glacial ice
Authors: Christner Brent C. , Mosley‐Thompson Ellen , Thompson Lonnie G. , Reeve John N.
Published: June 2003

Ice that forms the bottom 18 m of a 308 m ice core drilled from the Guliya ice cap on the Qinghan‐Tibetan plateau in Western China is over 750 000 years old and is the oldest glacial ice known to date. Fourteen bacterial isolates have been recovered from samples of this ice from ∼296 m below the surface (mbs). Based on 16S rDNA sequences, these are members of the α‐ and β‐proteobacterial, actinobacterial and low‐G + C Gram‐positive bacterial lineages. 16S rDNA molecules have also been amplified directly, cloned and sequenced from the ice‐core melt water. These originated from Pseudomonas and Acinetobacterγ‐proteobacterial species. These results demonstrate that bacteria can be recovered from water ice that has frozen for time periods relevant to biological survival through terrestrial ice ages or during interplanetary transport.