三江平原碟形洼地-岛状林土壤氮磷空间分布及生态化学计量特征

为阐明由碟形洼地-岛状林方向土壤养分的空间分布特征,选取非生长季中国科学院三江平原沼泽湿地生态试验站内的碟形洼地为研究对象,探讨土壤全氮和全磷含量及其化学计量比的空间分布特征及其影响因素。结果表明:由碟形洼地-岛状林方向,全氮、全磷和氮磷比在各样点的平均值分别呈"V"字、倒"N"字和"V"字型分布,土壤全氮、全磷与氮磷比含量的平均值分别为2278.11 mg/kg、820.50 mg/kg与2.44,变异系数为全氮(51.77%)氮磷比(36.07%)全磷(13.65%)。在0—50 cm土层内,全氮、全磷和氮磷比总体呈随土壤深度增加而逐渐降低的趋势,其中全氮主要集中于不同样点土壤的中上层,各样点的最高值均分布在土壤表层区域;全磷的富集深度与全氮相同,但在土壤20 cm深度各样点含量相近,后在20—50 cm深度内呈逐渐下降趋势;氮磷比在各样点的最高值与全氮和全磷分布总体一致,富集深度与两元素呈基本一致趋势。相关性分析表明,碟形洼地-岛状林方向土壤全氮与全磷之间均呈现出良好的相关关系,其中土壤有机质的分布,植物与水文状况、季节变化和土壤温度也在养分分布中起重要作用。     

Impact of air pollution and climate change on mental health outcomes: an umbrella review of global evidence

The impact of air pollution and climate change on mental health has recently raised strong concerns. However, a comprehensive overview analyzing the existing evidence while addressing relevant biases is lacking. This umbrella review systematically searched the PubMed/Medline, Scopus and PsycINFO databases (up to June 26, 2023) for any systematic review with meta-analysis investigating the association of air pollution or climate change with mental health outcomes. We used the R metaumbrella package to calculate and stratify the credibility of the evidence according to criteria (i.e., convincing, highly suggestive, suggestive, or weak) that address several biases, complemented by sensitivity analyses. We included 32 systematic reviews with meta-analysis that examined 284 individual studies and 237 associations of exposures to air pollution or climate change hazards and mental health outcomes. Most associations (n=195, 82.3%) involved air pollution, while the rest (n=42, 17.7%) regarded climate change hazards (mostly focusing on temperature: n=35, 14.8%). Mental health outcomes in most associations (n=185, 78.1%) involved mental disorders, followed by suicidal behavior (n=29, 12.4%), access to mental health care services (n=9, 3.7%), mental disorders-related symptomatology (n=8, 3.3%), and multiple categories together (n=6, 2.5%). Twelve associations (5.0%) achieved convincing (class I) or highly suggestive (class II) evidence. Regarding exposures to air pollution, there was convincing (class I) evidence for the association between long-term exposure to solvents and a higher incidence of dementia or cognitive impairment (odds ratio, OR=1.139), and highly suggestive (class II) evidence for the association between long-term exposure to some pollutants and higher risk for cognitive disorders (higher incidence of dementia with high vs. low levels of carbon monoxide, CO: OR=1.587; higher incidence of vascular dementia per 1 μg/m³ increase of nitrogen oxides, NO_x: hazard ratio, HR=1.004). There was also highly suggestive (class II) evidence for the association between exposure to airborne particulate matter with diameter ≤10 μm (PM₁₀) during the second trimester of pregnancy and the incidence of post-partum depression (OR=1.023 per 1 μg/m³ increase); and for the association between short-term exposure to sulfur dioxide (SO₂) and schizophrenia relapse (risk ratio, RR=1.005 and 1.004 per 1 μg/m³ increase, respectively 5 and 7 days after exposure). Regarding climate change hazards, there was highly suggestive (class II) evidence for the association between short-term exposure to increased temperature and suicide- or mental disorders-related mortality (RR=1.024), suicidal behavior (RR=1.012), and hospital access (i.e., hospitalization or emergency department visits) due to suicidal behavior or mental disorders (RR=1.011) or mental disorders only (RR=1.009) (RR values per 1°C increase). There was also highly suggestive (class II) evidence for the association between short-term exposure to increased apparent temperature (i.e., the temperature equivalent perceived by humans) and suicidal behavior (RR=1.01 per 1°C increase). Finally, there was highly suggestive (class II) evidence for the association between the temporal proximity of cyclone exposure and severity of symptoms of post-traumatic stress disorder (r=0.275). Although most of the above associations were small in magnitude, they extend to the entire world population, and are therefore likely to have a substantial impact. This umbrella review classifies and quantifies for the first time the global negative impacts that air pollution and climate change can exert on mental health, identifying evidence-based targets that can inform future research and population health actions.     

Metabolic reorganization and signal transduction during estivation in the spadefoot toad

The maximal activities of 28 enzymes, representing multiple pathways of intermediary metabolism, were quantified in the brain, liver and skeletal muscle of spadefoot toads Scaphiopus couchii, comparing control toads with animals that had estivated for 2 months. Estivation-induced changes in brain enzyme activities were consistent with suppressed glycolysis and increased ketone body and amino acid catabolism. In liver, estivation resulted in reduced activities of eight enzymes representing carbohydrate, amino acid, ketone body and phosphagen metabolism, but the maximal activity of malic enzyme increased by 2.4-fold. Estivation led to a large-scale reorganization of skeletal muscle affecting most of the enzymes analyzed. Activities of enzymes of carbohydrate catabolism were generally elevated except for glycogen phosphorylase and hexokinase, whereas those of enzymes of fatty acid synthesis and ketone body metabolism were reduced. Increased glutamate dehydrogenase activities in both brain and muscle, as well as activities of other amino-acid-catabolizing enzymes in muscle, correlated with specific changes in the free amino acids pools in those tissues (reduced glutamine activity, increased glutamate, alanine and valine activities) that appear to be related to protein catabolism, for the purposes of elevating urea levels. The effects of estivation on signal transduction systems were also assessed. Total activities of protein kinases A and C (PKA and PKC) were largely unaltered in toad tissues during estivation (except for a 57% reduction in liver total PKC), but in seven organs there were strong reductions in the percentage of PKA present as the active catalytic subunit in estivating animals, and three contained a much lower percentage of membrane-bound active PKC during estivation. Activities of protein phosphatase types 1, 2A, 2B, and 2C were also frequently reduced during estivation. Overall, these results suggest that anuran estivation involves metabolic reorganization, including changing the maximal activities of key enzymes of intermediary metabolism as well as depressing the metabolic rate by suppressing signal transducing enzymes.     

miR-124在抑郁症中的作用机制

抑郁症是世界范围内最常见的精神疾病之一,发病机制复杂,研究仍处于探索阶段。微RNA（miRNA）作为表观遗传机制的重要调控因子,在抑郁症的发生发展中起着重要作用。miR-124是神经系统中表达最丰富的miRNA之一,参与了神经元分化、小胶质细胞激活等生物事件。近年研究表明,miR-124在抑郁症患者和动物模型中表达异常,并参与了病理生理机制。然而,miR-124的表达异常情况及其相关机制的研究结果是较复杂的、甚至矛盾的。故本文对此进行梳理,总结了miR-124在抑郁症中的研究进展。     

甘麦大枣汤对抑郁模型大鼠海马神经元突触结构及结构蛋白表达的影响

目的:观察甘麦大枣汤对抑郁模型大鼠行为学及单胺递质的影响,并从突触结构及结构蛋白MAP-2与GAP-43表达改变探讨其潜在作用机制。方法:60只SD大鼠随机分为5组:正常对照组、模型组、氟西汀组(10.8mg/kg)、甘麦大枣汤高、低剂量组(9.72、4.86 g/kg),每组12只。除对照组外,其余各组大鼠均采用慢性不可预见性温和应激(CUMS)建立抑郁模型,并于造模同时给药组灌胃给药,连续21 d。采用糖水消耗实验和旷场测试评价大鼠抑郁样行为,ELISA法检测海马单胺递质5-HT、NE含量,Golgi染色观察神经元突触损伤情况,免疫组化法和Western blot法检测海马突触结构蛋白MAP-2和GAP-43的表达。结果:与对照组比较,抑郁模型大鼠糖水偏好度及自主活动评分均显著下降(P<0.01),海马5-HT、NE含量显著下降(P<0.01),树突棘缺失明显,同时MAP-2和GAP-43表达均显著下调(P<0.01);甘麦大枣汤干预后,模型大鼠抑郁样行为明显缓解(P<0.01),5-HT、NE含量显著升高(P<0.05),树突棘密度、长度及分枝增加,...     

遗传多样性与濒危植物保护生物学研究进展

尽管对于濒危物种的遗传学人们已经进行了大量研究,但是种群遗传学在植物保护中的实际地位尚存在很大争议。濒危物种的遗传多样性可能会由于遗传漂变、近交的作用而丧失;但这种丧失更可能是濒危的结果而不是濒危的起因。遗传多样性水平与物种生存力之间没有任何必然的联系。但植物种群遗传结构如果由于自交不亲和等位基因的丧失和与亲缘种杂交造成的遗传同化而发生改变,那么它对物种生存力会产生明显负作用。     

THE ROLE OF GENES OF LARGE EFFECT ON INBREEDING DEPRESSION IN MIMULUS GUTTATUS

Severe inbreeding depression is routinely observed in outcrossing species. If inbreeding load is due largely to deleterious alleles of large effect, such as recessive lethals or steriles, then most of it is expected to be purged during brief periods of inbreeding. In contrast, if inbreeding depression is due to the cumulative effects of many deleterious alleles of small effect, then it will be maintained in the face of periodic inbreeding. Whether or not inbreeding depression can be purged with inbreeding in the short term has important implications for the evolution of mating systems and the probability that a small population will go extinct. In this paper I evaluate the extent to which the tremendous inbreeding load in a primarily outcrossing population of the wildflower, Mimulus guttatus, is due to alleles of large effect. To do this, I first constructed a large outbred “ancestral” population by randomly mating plants collected as seeds from a natural population. From this population I formed 1200 lines that were maintained by self-fertilization and single seedling descent: after five generations of selling, 335 lines had survived the inbreeding process. Selection during the line formation is expected to have largely purged alleles of large effect from the collection of highly inbred lines. Because alleles with minor effects on fitness should have been effectively neutral, the inbreeding depression due to this class of genes should have been unchanged. The inbred lines were intercrossed to form a large, outcrossed “purged” population. Finally, I estimated the fitness of outbred and selfed progeny from the ancestral and purged populations to determine the contribution of major deleterious alleles on inbreeding depression. I found that although the average fitness of the outcrossed progeny nearly doubled following purging, the limited decline in inbreeding depression and limited increase in inbred fitness indicates that alleles of large effect are not the principle cause of inbreeding depression in this population. In aggregate, the data suggest that lethals and steriles make a minority contribution to inbreeding depression and that the increased outbred fitness is due primarily to adaptation to greenhouse conditions.     

Genetic analysis of inbreeding depression in plus tree 850.55 of Pinus radiata D. Don. II. Genetics of viability genes

 Most coniferous species exhibit severe inbreeding depression. Selfed individuals usually have decreased viability, reduced vigour and morphological defects. The number of filled seeds after selfing Pinus radiata plus tree 850.55 was 48% that of the outcrossing, and 26.1% of the selfed seedlings died at an early stage. The segregation of 172 markers (covering 56% of the genome) in selfed progenies of radiata pine plus tree 850.55 was studied. Based on the segregation ratio of the markers, genes associated with inbreeding depression on viability were identified (P<0.05). Using the Expectation/Conditional Maximization (ECM) algorithm, we estimated the location, degree of dominance and selection coefficient of viability genes. Nine viability genes were discovered. Seven of them appeared to be dominant and one partially dominant (degree of dominance=0.4). The other gene was overdominant or pseudo-overdominant, with selection coefficients for the two homozygotes of 0.4 and 0.42, respectively. Of the genes showing dominance or partial dominance, seven were sub-lethal with selection coefficients ranging from 0.55 to 0.79; one gene (SDPr), which was responsible for seedling death within the first month following germination, was lethal. Received: 13 December 1998 / Accepted: 28 December 1998