An Examination of the Association between 5-HTTLPR,Combat Exposure,and PTSD Diagnosis among U.S. Veterans

Objective

To examine the association between the 5-HTTLPR polymorphism of the serotonin transporter (SLC6A4) gene, combat exposure, and posttraumatic stress disorder (PTSD) diagnosis and among two samples of combat-exposed veterans.

Method

The first sample included 550 non-Hispanic Black (NHB) combat-exposed veterans. The second sample included 555 non-Hispanic White (NHW) combat-exposed veterans. Participants were genotyped for the 5-HTTLPR/rs25531 variants of the SLC6A4 gene. A structured clinical interview was used to diagnose PTSD. Combat and civilian trauma exposure were assessed with validated self-report instruments. Logistic regression was used to test for main effects of 5-HTTLPR on PTSD diagnosis as well as gene x environment (GxE) interactions after adjusting for sex, ancestry proportion scores, civilian trauma exposure, and combat exposure.

Results

Within the NHB sample, a significant additive effect was observed for 5-HTTLPR (OR = 1.502, p = .0025), such that the odds of having a current diagnosis of PTSD increased by 1.502 for each additional S’ allele. No evidence for an association between 5-HTTLPR and PTSD was observed in the NHW sample. In addition, no evidence for combat x 5-HTTLPR effects were observed in either sample.

Conclusion

The present study suggests that there may be an association between 5-HTTLPR genotype and PTSD diagnosis among NHB veterans; however, no evidence for the hypothesized 5-HTTLPR x combat interaction was found.     

Sequential colonization by river periphyton analysed by microscopy and molecular fingerprinting

1. An artificial glass substratum was incubated in the River Danube for a period of 28 days in order to detect the sequential colonization of microorganisms.
2. Light and fluorescent microscopy showed that microalgae and the picoalgal fraction on the slides increased rapidly over the first 2 weeks of colonization. Diatoms were numerically the most abundant component of the periphyton and their species richness and diversity increased rapidly in the early phase of colonization whereas diversity subsequently increased moderately.
3. Evenness of the diatom community was initially high, lower in the intermediate phase and again higher later on. Succession involving early, intermediate and late colonizer species was observed. Community composition during the first 5 days of colonization was very different from later stages whereas there were only minor changes subsequently.
4. Molecular community analysis by means of terminal restriction fragment length polymorphism analysis of PCR amplified 16S rRNA and 18S rRNA genes pointed to even larger differences between the composition of samples obtained early and late in the period.
5. The number of 18S rRNA and 16S rRNA terminal restriction fragments (T-RF-s) was variable over the colonization period and the fragment patterns of both the bacterial and eukaryotic portion of the microbial community were variable, with most T-RF-s unique to a single sample, suggesting a wide diversity and dynamic properties of periphytic organisms.     

Concerted transpositions of mobile genetic elements coupled with fitness changes in Drosophila melanogaster

In an inbred low-activity (LA) strain of Drosophila melanogaster with a low level of fitness and a complex of inadaptive characters, in situ hybridization reveals an invariant pattern of distribution of three copia-like elements (mdg-1, mdg-3, and copia). Rare, spontaneous, multiple transpositions of mobile elements in the LA strain were shown to be coupled with a drastic increase of fitness. A changed pattern of various types of mobile elements was also observed on selecting the LA strain for higher fitness. High-fitness strains show transpositions of mobile elements to definite chromosomal sites ("hot spots"). Concerted changes in the location of three different mobile elements were found to be coupled with an increase of fitness. The mdg-1 distribution patterns were also examined in two low-fitness strains independently selected from the high-fitness ones. Fitness decrease was accompanied by mdg-1 excision from the hot spots of their location usually detected in the high-fitness strains. The results suggest the existence of a system of adaptive transpositions of mobile elements that takes part in fitness control.      

Appearance of differentiation characteristics (Induction of Ah-Receptor-Dependent Genes) during cultivation of transformed cell clone K8 from embryonic rat fibroblasts

The differentiation status of fibroblasts can be characterized by their ability to induce Ah-receptor-dependent genes. The ability to induce Ah-receptor-dependent genes encoding cytochrome P450 isoforms, Ah-receptor repressor, and NADPH-quinine oxidoreductase were studied in the transformed cell clone K8 obtained from immortalized embryonic rat fibroblasts by treatment with benzo(a)pyrene and in the parental clone F27. Treatment with benz(a)anthracene did not induce the genes in the transformed clone K8 on passages 4–14, but the induction was recorded in the transformed clone beginning from the 16th passage and later, whereas in F27 cells the induction was observed throughout the experiment. Induction levels of mRNA of the induction-regulating genes encoding the Ah-receptor and Ah receptor nuclear translocator were similar in F27 cells and in the transformed cell clone K8 in both early and late passages. Electrophoretic mobility shift assay showed that in clone K8 transmission of the induction signal was disturbed in the early passages before interaction of the activated Ah-receptor with the recognizing region of DNA. Possible mechanisms responsible for the absence of induction in the early passages in the transformed cells are discussed.     

A comparative study of induction regulation in cytochromes family 1 P450 in cell cultures at different stages of tumor transformation

Lipophilic xenobiotics, including some carcinogenic agents and cytostatics, are metabolized by cytochrome P450 isoforms (CYP). In tumours expression of CYP genes and their inducibility are lower than in a homologous normal tissue. This phenomenon determines the known higher cytostatic stability of tumour cells. To clarify, at which particular stage of tumour transformation the level of family 1 CYP may change, we compared mRNA expression of CYP1A1, CYP1B1 and also of proteins regulated CYP expression: Ah receptor, ARNT and AHRR. For this aim we studied embryonic and fibroblast-like cells, in addition to cells of the same types but immortalized by the Rausher virus, or spontaneously after crisis. Besides, we investigated transformed clones obtained by means of benzo/a/pyrene action on Rausher virus-immortalized cells. Constitutive expression of genes studied in all cell cultures was shown. Benzo/a/anthracene induction increases the mRNA expression of all inducible genes (CYP1A1, CYP1B1, AHRR) in the original embryonic cells, in Rausher virus-immortalized cells, and in transformed clone K2. In both spontaneously immortalized cells and transformed clone K1 only CYP1B1 was induced. In transformed clone K8 no inducible gene was induced. In summary, we have shown that: (1) the ability of immortalized cells to CYP induction is determined not only by their capacity for a non-limited persistence, but also by the nature of immortalization; (2) despite their common genesis, the transformed clones differ in their ability to induce CYP. In addition to Ah receptor and ARNT, some other, yet unknown factors may also take part in CYP induction.     

Strong coupling of plant and fungal community structure across western Amazonian rainforests

The Amazon basin harbors a diverse ecological community that has a critical role in the maintenance of the biosphere. Although plant and animal communities have received much attention, basic information is lacking for fungal or prokaryotic communities. This is despite the fact that recent ecological studies have suggested a prominent role for interactions with soil fungi in structuring the diversity and abundance of tropical rainforest trees. In this study, we characterize soil fungal communities across three major tropical forest types in the western Amazon basin (terra firme, seasonally flooded and white sand) using 454 pyrosequencing. Using these data, we examine the relationship between fungal diversity and tree species richness, and between fungal community composition and tree species composition, soil environment and spatial proximity. We find that the fungal community in these ecosystems is diverse, with high degrees of spatial variability related to forest type. We also find strong correlations between α- and β-diversity of soil fungi and trees. Both fungal and plant community β-diversity were also correlated with differences in environmental conditions. The correlation between plant and fungal richness was stronger in fungal lineages known for biotrophic strategies (for example, pathogens, mycorrhizas) compared with a lineage known primarily for saprotrophy (yeasts), suggesting that this coupling is, at least in part, due to direct plant–fungal interactions. These data provide a much-needed look at an understudied dimension of the biota in an important ecosystem and supports the hypothesis that fungal communities are involved in the regulation of tropical tree diversity.     

New observations and reinterpretation on the enigmatic taxon Colombitherium (?Pyrotheria,Mammalia) from Colombia

Abstract: The controversial taxon Colombitherium tolimense (Mammalia) (probably Late Eocene in age) from Colombia, although known for nearly 40 years, still bears much mystery. Aside from the problematic ordinal attribution of the holotype and only specimen, its determination as an upper or lower jaw remains a highly debated issue. New observations include the presence of a contact facet on the distal face of the most posterior tooth, which indicates that the fragmentary jaw preserves three premolars and two molars; the M3, unpreserved but present, being most probably reduced. This new interpretation completely fits the morphology of the teeth. Furthermore, the shape of these latter and the deeper wear encompassed by their lingual part relative to the labial one is typical of upper dentition. This is in agreement with the internal curving of the roots of the anterior premolars and with several other arguments that lead interpreting the holotype of C. tolimense as a maxillary bearing P2‐M2. This new interpretation deepens the morphological gap between Colombitherium and other pyrotherians (except Proticia) and challenges further its referral to Pyrotheria. The peculiar morphology of Colombitherium relative to other pyrotherians is indeed striking. In fact, Colombitherium has nothing in common with pyrotherians but bilophodont cheek teeth, a feature largely widespread in placental mammals. It is here referred to ?Pyrotheria until additional evidence of its relationships is known. Associated with the putative removal of Proticia from Pyrotheria as argued by some authors, the hypothetical removal of Colombitherium from the order would adjust the widely accepted assumption that the pyrotherian bilophodont cheek teeth originated from bunodont cheek teeth. It would also make an origin from lophodont forms plausible. This in turn would have critical relevance, especially to the hypothesis that pyrotherians are notoungulates.