Serotonin transporter gene,childhood emotional abuse and cognitive vulnerability to depression

Meta‐analyses evaluating the association between the serotonin transporter polymorphism (5‐HTTLPR) with neuroticism and depression diagnosis as phenotypes have been inconclusive. We examined a gene–environment interaction on a cognitive vulnerability marker of depression, cognitive reactivity (CR) to sad mood. A total of 250 university students of European ancestry were genotyped for the 5‐HTTLPR, including SNP rs25531, a polymorphism of the long allele. Association analysis was performed for neuroticism, CR and depression diagnosis (using a self‐report measure). As an environmental pathogen, self‐reported history of childhood emotional abuse was measured because of its strong relationship with depression. Participants with the homozygous low expressing genotype had high CR if they had experienced childhood emotional maltreatment but low CR if they did not have such experience. This interaction was strongest on the Rumination subscale of the CR measure. The interaction was not significant with neuroticism or depression diagnosis as outcome measures. Our results show that 5‐HTTLPR is related to cognitive vulnerability to depression. Our findings provide evidence for a differential susceptibility genotype rather than a vulnerability genotype, possibly because of the relatively low levels of abuse in our sample. The selection of phenotype and environmental contributor is pivotal in investigating gene–environment interactions in psychiatric disorders.     

Large brood sizes of pied flycatcher, sparrowhawk and goshawk in peak microtine years: support for the mast depression hypothesis

The mast depression hypothesis (MDH) proposes that cyclic population fluctuations of microtines and other herbivores are an effect of cyclic seed cropping of plants. This is because high seed crops, termed masts, are produced at the expense of chemical defence against herbivores. It has generally been assumed that bird-hunting raptors produce high numbers of offspring when microtine prey are abundant because of reduced competition from generalist predators. However, this may also be caused by higher production of herbivorous insects, and thus insectivorous bird prey, because of lower contents of chemical defence compounds in some plant species, such as bilberry Vaccinium myrtillus and cowberry V. vitis-idaea. In Aust-Agder county, southern Norway, the mean brood size of pied flycatcher Ficedula hypoleuca, sparrowhawk Accipiter nisus and goshawk A. gentilis was higher in peak vole years than in other years. The effect was not due to variation in nest predation, as only successful nesting attempts were included in the analyses. For the pied flycatcher, the annual proportion of large broods (>6 fledglings) was positively correlated with the vole trapping index. No correlation was found between the offspring production of goshawks and the proportion of voles in their diet. During a 3-year light-trapping study of nocturnal moths prior to our study, four moth species whose larvae ate Vaccinium were commonest in the vole peak year. All these results are consistent with the MDH. Received: 16 March 1998 / Accepted: 20 April 1998     

粪菌移植通过微生物-肠-脑轴改善抑郁症的研究进展

人类粪菌移植(fecal microbiota transplantation,FMT)早在19世纪50年代的西方医学中便有临床应用.FMT已被证明可以很好地缓解艰难梭菌感染(Clostridium difficile infection,CDI)的胃肠道疾病,在调节微生物-肠-脑轴(microbiota-gut-br...     

Fisetin provides antidepressant effects by activating the tropomyosin receptor kinase B signal pathway in mice

Depression has been associated with a low‐grade chronic inflammatory state, suggesting a potential therapeutic role for anti‐inflammatory agents. Fisetin is a naturally occurring flavonoid in strawberries that has anti‐inflammatory activities, but whether fisetin has antidepressant effects is unknown. In this study, we exposed mice to spatial restraint for 2 weeks with or without treatment with fisetin. Immobility time in the forced swimming and tail suspension test after this restraint increased in the untreated group, but this increase did not occur in the fisetin group. We administered fisetin to Abelson helper integration site‐1 (Ahi1) knockout mice, which have depressive phenotypes. We found that fisetin attenuated the depressive phenotype of these Ahi1 knockout mice. We further investigated the potential mechanism of fisetin's antidepressant effects. Because TrkB is a critical signaling pathway in the mechanisms of depression, we examined whether phosphorylated TrkB was involved in the antidepressant effects of fisetin. We found that fisetin increased phosphorylated TrkB level without altering total TrkB; this increase was attenuated by K252a, a specific TrkB inhibitor. Taken together, our results demonstrated that fisetin may have therapeutic potential for treating depression and that this antidepressant effect may be mediated by the activation of the TrkB signaling pathway.

     

The nature of fisheries- and farming-induced evolution

Humans have a penchant for unintentionally selecting against that which they desire most. In fishes, unprecedented reductions in abundance have been associated with unprecedented changes in harvesting and aquaculture technologies. Fishing, the predominant cause of fish-population collapses, is increasingly believed to generate evolutionary changes to characters of import to individual fitness, population persistence and levels of sustainable yield. Human-induced genetic change to wild populations can also result from interactions with their domesticated counterparts. Our examination of fisheries- and farming-induced evolution includes factors that may influence the magnitude, rate and reversibility of genetic responses, the potential for shifts in reaction norms and reduced plasticity, loss of genetic variability, outbreeding depression and their demographic consequences to wild fishes. We also suggest management initiatives to mitigate the effects of fisheries- and farming-induced evolution. Ultimately, the question of whether fishing or fish farming can cause evolutionary change is moot. The key issue is whether such change is likely to have negative conservation- or socio-economic consequences. Although the study of human-induced evolution on fishes should continue to include estimates of the magnitude and rate of selection, there is a critical need for research that addresses short- and long-term demographic consequences to population persistence, plasticity, recovery and productivity.     

Consequences of near and far between-population crosses for offspring fitness in a rare herb

Crosses between plants from different populations may result in heterosis or outbreeding depression. However, despite its importance for conservation, little is known about the spatial scale over which these effects may arise. To investigate the consequences of between-population crosses at two distinct spatial scales, we conducted reciprocal crosses between four populations from two regions in the rare perennial herb Aster amellus . We assessed seed set and offspring fitness in a common garden experiment. Overall, between-population crosses within regions (10 km) resulted in 8% lower seed set than within-population crosses, while between-region crosses (70 km) resulted in 17% higher seed set than within-population crosses. Moreover, offspring from between-population crosses produced 18% more flower heads than offspring from within-population crosses. We conclude that hybridisation between A. amellus plants from different populations did not lead to immediate outbreeding depression and, thus, could represent a valid conservation option to increase genetic diversity. Moreover, our results suggest that the distance between populations affects the outputs of between-population crosses and therefore needs to be taken into account when promoting gene flow between populations.     

Impairment of long-term depression induced by chronic brain inflammation in rats

Although deficits in synaptic plasticity have been identified in aged or neuroinflamed animals with memory impairments, few studies have examined the cellular basis of plasticity in such animals. Here, we examined whether chronic neuroinflammation altered long-term depression (LTD) and studied the underlying mechanism of LTD impairment by neuroinflammation. Chronic neuroinflammation was induced by administration of lipopolysaccharide (LPS) to the fourth ventricle. Excitatory postsynaptic potentials were recorded extracellularly in the rat hippocampal CA1 area to examine alterations in synaptic plasticity. Chronic administration of LPS induced remarkable memory impairment in the Morris water maze test. N-methyl-d-aspartate receptor (NMDAR)-dependent LTD was almost absent in LPS-infused animals. The AMPA receptor (AMPAR)-mediated synaptic response was reduced in the LPS-infused group. These results suggest that reduction in NMDAR-dependent LTD might arise because of alterations in postsynaptic AMPARs as well as NMDARs and that such changes may be present in mild and early forms of Alzheimer-type dementia.     

Parental relatedness and major histocompatibility effects on early embryo survivorship in Atlantic salmon

Salmon have provided key insights into the relative influence of natural and sexual selection on major histocompatibility complex (MHC) variation. Natural selection on salmon MHC genes has been demonstrated in pathogen studies, and there is evidence of MHC-based mate choice (sexual selection). We tested whether parental MHC genes affect survivorship of juvenile Atlantic salmon (Salmo salar) by quantifying the influence of parental genome-wide relatedness and MHC genotype on survivorship to the swim-up stage. Thirteen microsatellite loci were used to estimate the influence of genome-wide relatedness between parents on offspring survivorship and MHC genotypes were determined by sequencing part of the class IIβ gene. Our results revealed no significant relationship between early offspring survivorship and genome-wide relatedness, predicted MHC heterozygosity, or MHC allelic similarity. Overall, our data are consistent with the contention that excess MHC heterozygosity in Atlantic salmon juveniles is due to sexual selection as well as differential survival of offspring due to MHC genotype.     

No relationship between microsatellite variation and neonatal fitness in Antarctic fur seals, Arctocephalus gazella

Published studies of wild vertebrate populations have almost universally reported positive associations between genetic variation measured at microsatellite loci and fitness, creating the impression of ubiquity both in terms of the species and the traits involved. However, there is concern that this picture may be misleading because negative results frequently go unpublished. Here, we analyse the relationship between genotypic variation at nine highly variable microsatellite loci and neonatal fitness in 1070 Antarctic fur seal pups born at Bird Island, South Georgia. Despite our relatively large sample size, we find no significant association between three different measures of heterozygosity and two fitness traits, birth weight and survival. Furthermore, increasing genetic resolution by calculating parental relatedness also yields no association between genetic variation and fitness. Our findings are consistent with necropsy data showing that most pups die from starvation or trauma, conditions that are unlikely to be influenced strongly by genetic factors, particularly if the benefits of high heterozygosity are linked to immune-related genes.