Spatially structured genetic variation in a broadcast spawning bivalve: quantitative vs. molecular traits

Understanding the origin, maintenance and significance of phenotypic variation is one of the central issues in evolutionary biology. An ongoing discussion focuses on the relative roles of isolation and selection as being at the heart of genetically based spatial variation. We address this issue in a representative of a taxon group in which isolation is unlikely: a marine broadcast spawning invertebrate. During the free-swimming larval phase, dispersal is potentially very large. For such taxa, small-scale population genetic structuring in neutral molecular markers tends to be limited, conform expectations. Small-scale differentiation of selective traits is expected to be hindered by the putatively high gene flow. We determined the geographical distribution of molecular markers and of variation in a shell shape measure, globosity, for the bivalve Macoma balthica (L.) in the western Dutch Wadden Sea and adjacent North Sea in three subsequent years, and found that shells of this clam are more globose in the Wadden Sea. By rearing clams in a common garden in the laboratory starting from the gamete phase, we show that the ecotypes are genetically different; heritability is estimated at 23%. The proportion of total genetic variation that is between sites is much larger for the morphological additive genetic variation (QST = 0.416) than for allozyme (FST = 0.000-0.022) and mitochondrial DNA cytochrome-c-oxidase-1 sequence variation (phiST = 0.017). Divergent selection must be involved and intraspecific spatial genetic differentiation in marine broadcast spawners is apparently not constrained by low levels of isolation.     

Long-term growth hormone treatment preserves GH-induced memory and mood improvements: a 10-year follow-up study in GH-deficient adult men

Growth hormone (GH) replacement therapy with duration of several years is known to be safe and beneficial in GH-deficient adult patients. However, long-term follow-up data on GH substitution, cognition, and well-being are scarce. The purpose of this study was to investigate whether the benefits of GH replacement in psychological functioning found in previous studies lasting up to 2 years are preserved over a 10-year follow-up period. Twenty-three men (mean age at baseline 28.6 years) with childhood-onset GH deficiency were studied during a 10-year period of GH substitution. Memory tasks, mood questionnaires, and IGF-I values were obtained at baseline and after 0.5, 1, 2, 3, 5, and 10 years of GH substitution. Both mood and memory improved during GH therapy. After 6 months of treatment, anxiety and tension were reduced and vigor had improved. Memory improved after 1 year of substitution. These improvements were maintained during the 10-year follow-up period. Higher intra-subject IGF-I levels were associated with better mood (anxiety, tension, vigor). This study shows that 10 years of GH therapy is beneficial in terms of well-being and cognitive functioning in childhood-onset GH-deficient men. It may be concluded that once the decision to start GH treatment has been taken, this may imply that GH therapy has to be continued for a long period to maintain the psychological improvements and to prevent a relapse.     

Reactive type II pneumocytes in bronchoalveolar lavage fluid

OBJECTIVE: To evaluate the prevalence of reactive type II pneumocytes (RPII) in bronchoalveolar lavage (BAL) fluid samples obtained from patients with various pulmonary disorders. STUDY DESIGN: Consecutive BAL fluid samples were screened for the presence of RPII on May-Grünwald-Giemsa-stained cytocentrifuge preparations. BAL fluid samples with and without RPII were compared with regard to prevalence, associated clinical diagnoses and cytologic findings. RESULTS: RPII were generally large cells with a high nuclear:cytoplasmic ratio and deeply blue-stained, vacuolated cytoplasm. Most RPII occurred in cohesive cell groups, and the vacuoles tended to be confluent. Cytologic findings associated with RPII were foamy alveolar macrophages, activated lymphocytes and plasma cells. RPII were present in 94 (21.7%) of 433 included BAL fluid samples. The highest prevalences were noted in patients with systemic inflammatory response syndrome and alveolar hemorrhage. In addition, RPII tended to occur more frequently in ventilator-associated pneumonia, Pneumocystis carinii pneumonia, extrinsic allergic alveolitis and drug-induced pulmonary disorders. In contrast, RPII were not observed in BAL fluid samples obtained from patients with sarcoidosis. CONCLUSION: RPII were prevalent in about 20% of BAL fluid specimens. They were associated mainly with conditions of acute lung injury and not observed in sarcoidosis.     

Correlation between thyroid hormone status and hepatic hyperplasia and hypertrophy caused by the peroxisome proliferator-activated receptor alpha agonist Wy-14,643

BACKGROUND: The metabolic inhibitor rotenone inhibits hepatocellular proliferation and the incidence of liver cancer resulting from exposure to the PPARalpha agonist Wy-14,643, via unknown mechanisms. Since the absence of thyroid hormones diminishes hepatomegaly, an early biomarker for the hepatocarcinogenicity induced by PPARalpha agonists, this study was undertaken to investigate whether rotenone might interference with the ability of Wy-14,643 to alter the animal thyroid status. METHODS: Male B6C3F1 mice were given Wy-14,643 (100 ppm), rotenone (600 ppm) or a mixture of both, in the feed for 7 days. Bromodeoxyuridine (BrDU), marker of cell replication, was delivered through subcutaneously implanted osmotic mini-pumps. At the end of the experiment, sera were collected and corticosterone and thyroid hormone levels were measured by solid-phase radioimmunoassay kits. In addition, liver tissue samples were stained immunohistochemically for BrDU to determine percentages of labeled cells. Further, cell surface area was determined from images generated by a Zeiss Axioplan microscope equipped with a plan Neofluar x40 0.75 na objective. Tracings of individual hepatocyte perimeters were then analyzed and cell-surface areas were calculated using MicroMeasure FL-4000. RESULTS: Wy-14,643 caused a significant increase in liver weights, hepatocyte BrDU labeling index (LI), and hepatocyte surface area. In animals which received both Wy-14,643 and rotenone simultaneously, all of these effects were significantly less pronounced compared with mice that received Wy-14,643 alone. Rotenone alone decreased liver weights, LI and surface area. The Free Thyroid Index (FTI), which provides an accurate reflection of the animal's thyroid status, was 5.0 +/- 0.3 in control mice. In animals exposed to rotenone, these values decreased to 2.0 +/- 0.9, but in animals which received Wy-14,643, levels increased significantly to 7.7 +/- 0.9. FTI values decreased to 3.4 +/- 0.8 in mice receiving both rotenone and Wy-14,643. CONCLUSION: A strong correlation was observed between the animal thyroid status and both, hepatocyte proliferation (r2 = 0.62), and hepatocyte surface area (r2 = 0.83). These results support the hypothesis that the thyroid status of the animal plays a role in PPARalpha-induced hepatocellular proliferation and liver cell enlargement. Both these events are known to contribute to the expression of liver cancer in response to the activation of PPARalpha.     

Realized heritability and repeatability of risk-taking behaviour in relation to avian personalities

Personalities are general properties of humans and other animals. Different personality traits are phenotypically correlated, and heritabilities of personality traits have been reported in humans and various animals. In great tits, consistent heritable differences have been found in relation to exploration, which is correlated with various other personality traits. In this paper, we investigate whether or not risk-taking behaviour is part of these avian personalities. We found that (i) risk-taking behaviour is repeatable and correlated with exploratory behaviour in wild-caught hand-reared birds, (ii) in a bi-directional selection experiment on 'fast' and 'slow' early exploratory behaviour, bird lines tend to differ in risk-taking behaviour, and (iii) within-nest variation of risk-taking behaviour is smaller than between-nest variation. To show that risk-taking behaviour has a genetic component in a natural bird population, we bred great tits in the laboratory and artificially selected 'high' and 'low' risk-taking behaviour for two generations. Here, we report a realized heritability of 19.3 +/- 3.3% (s.e.m.) for risk-taking behaviour. With these results we show in several ways that risk-taking behaviour is linked to exploratory behaviour, and we therefore have evidence for the existence of avian personalities. Moreover, we prove that there is heritable variation in more than one correlated personality trait in a natural population, which demonstrates the potential for correlated evolution.     

Individual differences in the use of social information in foraging by captive great tits

We investigated individual differences in copying behaviour of captive great tits, Parus major, by analysing their response to a tutor indicating a new feeding site. We used two groups, each of seven male birds, labelled 'fast' and 'slow' explorers based on previous studies in which consistent individual differences in the speed of exploring were found. The birds were trained to search for food hidden in a number of differently coloured and shaped feeders, and later to search in only one type of feeder. During the tests, food was absent and the birds were observed in two different situations: alone or in the presence of a tutor, a bird that had been trained to feed in a different kind of feeder. When alone, slow birds readily extended their search to other feeders while fast birds did not change their routine of visiting the previously rewarded ones. In the presence of the tutor, the opposite occurred: slow birds did not change their behaviour while fast birds significantly increased their visits to the feeders indicated by the tutor. Fast and slow individuals thus differ in their foraging and copying behaviour, consistent with the producer-scrounger model. Copyright 2000 The Association for the Study of Animal Behaviour.     

Differential cell analysis of cytocentrifuged bronchoalveolar fluid samples affected by the area counted

OBJECTIVE: To investigate variations in the differential cell counts between the quadrants of cytocentrifuged bronchoalveolar lavage (BAL) fluid preparations and to evaluate the diagnostic impact of these differences in interstitial lung diseases (ILD). STUDY DESIGN: BAL fluid samples obtained from 30 patients suspected of having ILD or pneumonia were cytocentrifuged and additionally stained with May-Grünwald-Giemsa stain. Two observers differentiated 200 cells in each quadrant as well as in a circular pattern around the center of the cytocentrifuge spot. RESULTS: Lymphocytes and alveolar macrophages were not randomly distributed on the cytocentrifuge spot. Ten samples of patients with histologically confirmed ILD were selected to test the diagnostic impact using a validated computer program. The predicted diagnosis did not correspond to the histologic diagnosis for one quadrant from 1 of these 10 samples (sarcoidosis instead of idiopathic pulmonary fibrosis), whereas the differential cell counts performed around the center of the cytocentrifuge spot provided the correct diagnosis in all cases. CONCLUSION: BAL fluid differential cell counts varied between the quadrants of the cytocentrifuge spot. The center of the cytocentrifuge spot appeared to be the most reliable area. Therefore, cell counting is recommended in a circular pattern around the center of the cytocentrifuge spot.     

Short-term hypoxia/reoxygenation activates the angiogenic pathway in rat caudate putamen

In response to hypoxia, tissues have to implement numerous mechanisms to enhance oxygen delivery, including the activation of angiogenesis. This work investigates the angiogenic response of the hypoxic caudate putamen after several recovery times. Adult Wistar rats were submitted to acute hypoxia and analysed after 0 h, 24 h and 5 days of reoxygenation. Expression of hypoxia-inducible factor-1 alfa (HIF-1α) and angiogenesis-related genes including vascular endothelial growth factor (VEGF), adrenomedullin (ADM) and transforming growth factor-beta 1 (TGF-β1) was determined by both RT-PCR and ELISA. For vessel labelling, lectin location and expression were analysed using histochemical and image processing techniques (fractal dimension). Expression of Hif-1α, Vegf, Adm and Tgf-β1 mRNA rose immediately after hypoxia and this increase persisted in some cases after 5 days post-hypoxia. While VEGF and TGF-β1 protein levels increased parallel to mRNA expression, ADM remained unaltered. The quantification of the striatal vessel network showed a significant augmentation at 24 h of reoxygenation. These results reveal that not only short-term hypoxia, but also the subsequent reoxygenation period, up-regulate the angiogenic pathway in the rat caudate putamen as a neuroprotective mechanism to hypoxia that seeks to maintain a proper blood supply to the hypoxic tissue, thereby minimizing the adverse effects of oxygen deprivation.     

Assessment of lexical semantic judgment abilities in alcohol-dependent subjects: An fMRI study

Neuropsychological studies have shown that alcohol dependence is associated with neurocognitive deficits in tasks requiring memory, perceptual motor skills, abstraction and problem solving, whereas language skills are relatively spared in alcoholics despite structural abnormalities in the language-related brain regions. To investigate the preserved mechanisms of language processing in alcohol-dependents, functional brain imaging was undertaken in healthy controls (n=18) and alcohol-dependents (n=16) while completing a lexical semantic judgment task in a 3 T MR scanner. Behavioural data indicated that alcohol-dependents took more time than controls for performing the task but there was no significant difference in their response accuracy. fMRI data analysis revealed that while performing the task, the alcoholics showed enhanced activations in left supramarginal gyrus, precuneus bilaterally, left angular gyrus, and left middle temporal gyrus as compared to control subjects. The extensive activations observed in alcoholics as compared to controls suggest that alcoholics recruit additional brain areas to meet the behavioural demands for equivalent task performance. The results are consistent with previous fMRI studies suggesting compensatory mechanisms for the execution of task for showing an equivalent performance or decreased neural efficiency of relevant brain networks. However, on direct comparison of the two groups, the results did not survive correction for multiple comparisons; therefore, the present findings need further exploration.