巴拉巴按蚊人工交配中雄蚊蚊龄与受精率的关系

自McDaniel和Horsfall(1957)介绍了伊蚊的人工交配法后,许多原来在实验室内不易自然交配,因而无法繁殖的蚊种,已可在室内大量繁殖以供实验研究之用。1966年Esah和Scanlon用人工交配法,在室内饲养巴拉巴按蚊获得成功。国内四川医学院及成都生物制品研究所亦于1976年在室内同时建立了海南白沙巴拉巴按蚊品系。由于工作的需要,我们通过人工交配对该蚊种进行了饲养繁殖。但在多次人工交配中,雌蚊受精率常不一致,有时只有30％左右,有时则可高达80％以上。这种受精率的不稳定是否与雄蚊蚊龄有相应关系?为此,我们用羽化后12天以内不同日龄的雄蚊,分别进行了人工交配,以观察雄蚊日龄与其对雌蚊授精率之间,有无必然的相应关系。     

昆明按蚊与凉山按蚊的种间关系

昆明按蚊(Anopheles knnmingensis Dong and Wang 1985)与凉山按蚊(An.liangshanensis Kang et al.1984)的种间关系,一直是蚊虫分类学家和疟疾研究工作者十分关注的问题。我们运用杂交实验、抱握器运动频率、形态分类等方法,对这两种蚊进行对比观察,证实二者为同一种按蚊。     

四川省蚊类分布与地貌的关系

经历年来调查全省已报告蚊虫10属120种,分布于168个县、市,占全省县、市的87%。本文参照四川省综合自然区划(王告函等,1981),划分为平原、丘陵、山地和高原4个区、11个亚区,即:成都平原、盆中浅丘区、盆中深丘区、盆东平行岭谷、盆周山地、川西南山地、康定木里巴塘高山深谷区、岷山邛崃山山地、马尔康理塘切割高原、若尔盖红原沼泽区和石渠色达丘状高原。各区划内蚊虫种类分布的差别是明显的(见表)。山地(表内Ⅳ—Ⅷ)蚊虫种类最多,占全省种类的85%(102/120),其余依次为丘陵,占64%(77/120),平原占55%(66/120),高原仅占10%(12/120)。各地貌区…     

雪鹭

正雪鹭(Egretta Thula)为小型涉禽,其属名源于法国的一种苍鹭。雪鹭身长55~65 cm,重约375 g。其体形呈纺锤形,体羽疏松,全身覆盖着洁白的羽毛,颈背有丝状蓑羽。19世纪末至20世纪初,洁白轻盈的雪鹭羽毛在制帽业风行一时。1886年,每盎司雪鹭羽毛价格高达32美元,约为现黄金价格的2倍。2015年12月20日,加籍华人摄影师陈胜先生在墨西哥巴亚尔塔港用Canon 5d MarkⅢ带EF70-200 f2.8L ISⅡUSM镜头拍摄。     

鹭林拍鹭

地处热带的海南岛,有大面积的稻田,河流纵横,鱼塘、虾塘密布,是鹭科鸟类最佳栖居环境。中国鹭科鸟类有21种,其中18种在海南岛有分布记录。每年冬天,还有为数众多的鹭鸟从大陆飞到海南越冬。2002年6月21日的海南日报刊登的一则图片新闻“鹭鸶当选儋州市鸟”吸引了我的注意。出于对鹭鸟的向往,决定前去探访。 联系好车辆沿海南西线环岛高速公路直奔儋州。进入洛基镇乡村公路,连绵成片的稻田,起伏平缓的小丘,静静流淌的河流,绿树翠竹环绕的村庄,这些海南乡村常见的景色汇聚在一起,构成鹭类栖息繁衍的理想环境。远远地看见一个小土丘,其上耸立着一座造型还算优美的4层钢筋混凝土楼阁,四周用砖砌了围墙。进     

生物之间的关系

正地球上生活着各式各样的生物,每一个或一种生物的生存都不是也不可能是独立完成的,它必然受到其他生物的影响。自然界生物之间的关系多种多样,从大的方面讲生物之间的关系包括种内关系和种间关系。种内关系是发生在同一种群内部个体之间的关系,包括种内互助和种内斗争;种间关系是不同物种个体之     

护鹭人家

京族三岛由山心岛,万尾岛和巫头岛组成,是我国京族人民惟一居住的地方。她们与越南的万柱岛隔海相望,是散布在祖国大陆海岸线最西南端的三颗明珠。     

鹭科鸟类群落的空间生态和种间关系

本文应用空间生态位理论,分析了浙江汰公山常绿落叶针阔混交林鹭类繁殖季节的群落结构。鹭类群落由池鹭Ａｒｄｅｏｌａ ｂｃｃｈｕｓ、白鹭Ｅｇｒｅｔｔａ ｇａｒｚｅｔｔａ、夜鹭Ｎｙｃｔｉｃｏｒａｘ ｎｙｃｔｉｃｏｒａｘ、牛背Ｂｕｂｕｌｃｕｓ ｉｂｉｓ组成。根据鹭类的水平分布、垂直分布、栖位分布的生态位宽度值,采用Ｓｃｈｏｅｎｅｒ（１９６８）生态位重叠,Ｃｏｄｙ（１９７４）“总和α”的方法制作了落落矩陈表和     

尿酸与DNA损伤之间关系的研究进展

尿酸是人体嘌呤代谢的最终产物,高于生理浓度的尿酸通常伴随细胞内氧化应激和活性氧(reactive oxygen species, ROS)增多,进而造成细胞内DNA损伤。DNA损伤反应及其引起的细胞死亡会促进内源性嘌呤增多,进一步导致尿酸升高。同时,DNA损伤反应可引起炎症、胰岛素抵抗、脂质代谢等异常,从而导致糖尿病、慢性肾脏疾病、非酒精性脂肪肝病等疾病的发生。这可能是高浓度尿酸成为多种慢性代谢性疾病独立危险因素的原因之一。因此,研究尿酸与DNA损伤之间的关系有助于深入了解尿酸的生理功能,为预防高尿酸血症及其相关疾病,并寻找潜在治疗靶点提供理论依据。     

Competition between tadpoles and mosquito larvae

Tadpoles and mosquito larvae often co-occur, and may compete for scarce resources. However, competition between such distantly related organisms has attracted less scientific attention than have interactions among closely related taxa. We examined ecological interactions in two tadpole-mosquito systems in southeastern Australia, one from freshwater ponds (Limnodynastes peronii and Culex quinquefasciatus) and one from brackish-water habitats (Crinia signifera and Ochlerotatus australis). Diets of these tadpoles and mosquito larvae overlap considerably, potentially leading to competition for food. Laboratory experiments show that, in both study systems, mosquitoes reduced the growth rates of tadpoles, and tadpoles reduced the growth rates and survival of mosquito larvae. These negative effects were seen even at high food levels. Thus, our study suggests that tadpoles and mosquito larvae affect each other strongly, and do so via pathways other than simple consumptive competition. Because mosquitoes are important vectors for human diseases, the global decline in amphibian populations may have more impact on human health than has generally been anticipated.     

The complex interplay between mosquito positive and negative regulators of Plasmodium development

The malaria parasite, Plasmodium, requires sexual development in the mosquito before it can be transmitted to the vertebrate host. Mosquito genes are able to substantially modulate this process, which can result in major decreases in parasite numbers. Even in susceptible mosquitoes, haemolymph proteins implicated in systemic immune reactions, together with local epithelial responses, cause lysis of more than 80% of the ookinetes that cross the mosquito midgut. In a refractory mosquito strain, immune responses lead to melanisation of virtually all parasites. Conversely, certain mosquito genes have an opposite effect: they are used by the parasite to evade defence reactions. Detailed understanding of the interplay between positive and negative regulators of parasite development could lead to the generation of novel approaches for malaria control through the vector.     

阿尔采末病与免疫炎症反应的相关性

阿尔采末病（Ａｌｚｈｅｉｍｅｒ’ｓｄｉｓｅａｓｅ,ＡＤ）可能是中枢神经系统内免疫活性细胞过程激活而导致的免疫炎症反应,其病灶周围存在大量激活的小胶质细胞和星形细胞,可产生大量补体,炎性细胞因子,急性期反应物等导致神经细胞损伤,破坏和死亡。同时体内寂体调节剂和抑制性细胞因子的水平明显长高,虽然不足以保护神经元免遭破坏,但却提示抑制或阻断中枢神经系统的免疫炎症反应的药物可能在ＡＤ的防治中具有重要作用。     

The relation between reproductive value and genetic contribution

What determines the genetic contribution that an individual makes to future generations? With biparental reproduction, each individual leaves a “pedigree” of descendants, determined by the biparental relationships in the population. The pedigree of an individual constrains the lines of descent of each of its genes. An individual’s reproductive value is the expected number of copies of each of its genes that is passed on to distant generations conditional on its pedigree. For the simplest model of biparental reproduction (analogous to the Wright–Fisher model), an individual’s reproductive value is determined within ∼10 generations, independent of population size. Partial selfing and subdivision do not greatly slow this convergence. Our central result is that the probability that a gene will survive is proportional to the reproductive value of the individual that carries it and that, conditional on survival, after a few tens of generations, the distribution of the number of surviving copies is the same for all individuals, whatever their reproductive value. These results can be generalized to the joint distribution of surviving blocks of the ancestral genome. Selection on unlinked loci in the genetic background may greatly increase the variance in reproductive value, but the above results nevertheless still hold. The almost linear relationship between survival probability and reproductive value also holds for weakly favored alleles. Thus, the influence of the complex pedigree of descendants on an individual’s genetic contribution to the population can be summarized through a single number: its reproductive value.THE most obvious feature of sexual reproduction is that each individual has two parents. Yet, the pedigrees that describe biparental relationships have received surprisingly little attention, compared with the genealogies that describe the uniparental relationships of genes. (Throughout, we refer to relationships between genes as their “genealogy”, in contrast to the “pedigree” of biparental relationships; genealogy should be understood as a shorthand for “gene genealogy”.) Following the rediscovery of Mendelian genetics, attention focused on the random genetic drift of discrete alleles and on the converse process of inbreeding, by which genes become identical by descent. There has of course been substantial work on the fate of genes within a given pedigree (e.g., Smith 1976, Cannings et al. 1978; Thompson et al. 1978), but relatively little on the pedigrees themselves.Pedigrees are of interest in their own right: it is natural to ask who our ancestors were (Chang 1999; Rohde et al. 2004) and, conversely, how many descendants we will each leave. But, from a genetic point of view, the pedigree constrains what genes can be passed on: with Mendelian inheritance, selection acts solely through the different contributions made by individuals to the pedigree. The recent availability of genomic sequences may focus more attention on pedigrees: given sufficient sequence, we can infer the pedigree many generations back; and given this pedigree, we can ask what contribution is likely to be made to future generations by each ancestral genome. These questions are long standing (Thompson et al. 1978; Thompson 1979a, b), but it has become feasible to answer them only in the past few years (Huff et al. 2011).The notion of reproductive value was introduced by Fisher (1930) to study populations structured by age. The reproductive value of an individual of a given age is its expected future contribution to the population (conditional on having survived to that age). Caswell (1982) generalized this to populations with an arbitrary structure (for example, where individuals vary in size or microhabitat). Grafen (2006) emphasizes that reproductive value can be ascribed to individuals as well as classes and shows rigorously that reproductive value is the target of selection. In the long term, alleles that increase the reproductive value will be the ones that increase, and traits will evolve that tend to maximize an individual’s reproductive value. In this setting, an individual’s reproductive value is defined to be its expected genetic contribution, that is, the expected number of copies of one of its alleles that it leaves in distant future generations, conditional on its pedigree of descendants. Once a pedigree is specified, one can superpose the passage of neutral alleles: offspring, independently, sample one allele from each parent. In this way an individual’s reproductive value is defined to be a function of its pedigree. Thus, we structure the population by the pedigree that connects every individual, rather than with a coarser structure by age or class.An individual’s reproductive value is determined within ∼10 generations, whereas its ultimate genetic contribution is determined over very long timescales. Here, we examine the relationship between pedigrees and genealogies over intermediate timescales of a few tens of generations.It is crucial to realize that overall genetic contribution to future generations is much more complex than simply the reproductive value, which gives the expected contribution at any one locus. The key result of this article is that the reproductive value of an individual determines the survival probability of its genes, but conditional on survival, the distribution of the number of copies of an allele in future generations is the same for all individuals, independent of their reproductive value. This result applies to a single genetic locus. Most of an individual ancestor’s genome is lost, but some small blocks survive in large numbers (Baird et al. 2003). By investigating simple summary statistics of the distribution of surviving blocks, we illustrate that the influence of the pedigree on the whole complex distribution of genetic contribution of an individual is also determined by its reproductive value. Thus, over these intermediate timescales, from the point of view of allele frequencies, the tangled web of relationships that forms an individual’s pedigree can be completely captured in a single number: the reproductive value.