Habitat-associated morphological divergence in two Neotropical fish species

We examined intraspecific morphological diversification between river channel and lagoon habitats for two Neotropical fish ( Bryconops caudomaculatus , Characidae; Biotodoma wavrini , Cichlidae). We hypothesized that differences between habitats (e.g. flow regime, foraging opportunities) might create selective pressures resulting in morphological divergence between conspecific populations. We collected fish from four channel-lagoon habitat pairs in the Río Cinaruco, Venezuela, and compared body morphology using geometric morphometrics. There were two aspects of divergence in both species: (1) placement of maximum body depth and (2) orientation of the mouth. For both species, maximum body depth was positioned more anteriorly (i.e. fusiform) in the river channel than in lagoons. Both species exhibited a relatively terminal mouth in lagoons compared to the channel. The mouth of B. caudomaculatus was relatively upturned, whereas the mouth of B. wavrini was relatively subterminal, in channel habitats. Observed morphological patterns are consistent with functional morphological principles suggesting adaptive divergence. We also show that spatial distance between habitats, presumably reflecting rates of population mixing, appears to have constrained diversification. For both species, morphological divergence increased with distance between habitats. Thus morphological divergence between channel and lagoon habitats apparently reflects a balance between diversification driven by natural selection, and homogenization driven by population mixing.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 80 , 689–698.     

新疆维吾尔族HLA-Cw基因座遗传多态性调查 The Study of HLA-Cw Polymorphism in Uygur Population

采用序列特异性寡核苷酸探针杂交技术（PCR-SSOP）对146位新疆维吾尔族无关个体HLA-Cw基因座进行基因分型,研究该民族HLA-Cw基因座遗传多态性,建立新疆维吾尔族HLA-Cw基因频率数据库。检出18种等位基因,基因频率分布在0.0069~02460,其中HLA-Cw*04、07、08、14基因频率比较高,基因频率分别为02460、0.1151、0.1010、0.1202,共占新疆维吾尔族可检出等位基因的58.23%,PCR-SSOP分型技术使新疆维吾尔族HLA-Cw基因座空白基因频率降至0.0064。经χ2检验,基因型分布符合Hardy-Weinberg平衡定律。建立民族HLA-Cw基因座基因频率数据库,为临床器官移植配型、人类学、法医学提供重要的群体遗传学资料。 Abstract:The HLA-Cw loci polymorphism in Uygur population was investigated using the PCR- sequence specific oligonucleotide probe (SSOP) method,and the genetic database on the distribution of gene frequency of the HLA-Cw loci was established.From 146 individuals of Uygur population,18 HLA-Cw alleles were detected.The gene frequency was from 0.0069 to 0.2460.The four most common alleles were HLA-Cw*04(24.60%)、07(11.51%)、08(1010%)、14(12.02%),and they covered 58.23% of total alleles detected from Uygur population.We have made a survey of HLA-Cw alleles frequencies in a Uygur population,with blank frequency being lowered to 0.0064.The distribution of genotype frequencies met the law of Hardy-Weinberg equilibrium by hi-square test.The frequency data can be used in forensic and paternity tests to estimate the frequency of a DNA profile in the Uygur population,transplant matching and anthropology.     

The endocrine control of phase transition: some new aspects

Abstract. The present article summarizes some recent findings relating to the underlying mechanism of phase transition in locusts, from the nonswarming solitarious phase to the swarming gregarious phase. These phases differ in many traits, such as colouration, morphometrics and behaviour. The most comprehensive theory at present to explain the switch from the nonswarming to the swarming form is that the locusts are brought together by the heterogeneity of the environment. They gather at preferential structures and food plants and physical contact then stimulates individuals to gregarize. Phase change can also be transferred across generations by maternal pheromones. The endocrine regulation of phase polymorphism is still not fully understood. The role of ecdysteroids has been studied, so far with no final conclusion. It is remarkable that the prothoracic glands persist longer in isolated-reared adults, which implies that these glands continue to play a role, although they no longer release important amounts of ecdysteroids. Juvenile Hormone, without any doubt, induces certain solitarious characteristics, such as green colouration, but is not the primary causal factor. A real breakthrough was the discovery of [His⁷]-corazonin, made possible by using a novel assay system, the Okinawa albino mutant of Locusta migratoria , which was known to be deficient in this hormone. This peptide, which is produced in the brain and is most likely released via the corpora cardiaca, promotes the gregarious black pigmentation. It also plays a role in morphometrical phase change as well as in behavioural alterations. Corazonin is apparently quite an important peptide not only in locusts, but also in insects in general.     

Purification, isolation and search for possible functions of a phase-related 6080-Da peptide from the haemolymph of the desert locust, Schistocerca gregaria

Abstract. A novel 6-kDa peptide has been isolated from the haemolymph of the desert locust, Schistocerca gregaria (Forskal) (Orthoptera: Acrididae) , and fully identified. Its concentration is higher in crowd-reared (gregarious) animals than in isolated-reared (solitarious) ones. Its concentration decreases progressively from generation to generation with solitarization of gregarious locusts. The peptide is also present in freshly laid eggs. The concentration in eggs is higher in those from crowd-reared locusts. It is likely that the peptide is transferred from the female's haemolymph into the eggs because injection of the peptide into females before oviposition increases the amount of the 6-kDa peptide in the eggs. A two-step HPLC purification procedure for this peptide is described. It allowed several bioassays to test for a possible function. Although the peptide's concentration in the haemolymph is high (0.1 m m ), which suggests some physiological function, we have as yet not been able to identify a function. We hypothesize that the 6-kDa peptide may somehow play a role as a maternal factor in the determination of the phase-state of the offspring.     

K型小麦细胞质雄性不育系育性恢复基因的RAPD和ISSR标记

利用RAPD和ISSR分子标记对K型小麦(Triticum aestivum L.)雄性不育恢复系LK783的主效恢复基因进行了标记定位.以K冀5418A//911289/LK783三交F1分离群体的极端不育株和极端可育株分别建立保持池和恢复池,利用418个RAPD和33个ISSR引物对两池间的多态性进行了研究.分析表明RAPD引物OPK18和ISSR引物UBC-845在两池间扩增出稳定的多态性差异,在分离群体上的验证结果表明LK783的育性恢复基因与两个引物的扩增位点有连锁关系,在染色体上位于两个引物的扩增位点之间,与OPK18450的遗传距离为(15.07±6.28)cM (centiMorgan),与UBC-845800的遗传距离为(8.20±4.85)cM.这两个引物可应用于对育性恢复基因的标记辅助选择.最后,利用中国春缺体-四体系和双端体系进一步将UBC-845800定位于1BS, 表明LK783的育性恢复基因也位于1BS.     

参考家系鸡黑素皮质素受体3基因多态性与体重关系研究

鼠遗传学研究显示黑素皮质素受体3（melanocortin-3 receptor,MC3R）和MC4R在能量平衡控制中具有互补作用。敲除MC3R基因鼠表现为独有的代谢综合征和增加脂肪重量。以8周龄高体重或低体重独立选择的高体重系（high weight,HW）和低体重系（low weight,LW）白洛克鸡3代参考家系群体作为实验材料,发现了5个新的MC3R基因单核苷酸多态性（single nucleotide polymorphisms,SNPs）;建立了基于限制性内切酶Dde I的MC3R基因型的PCR-RFLP分子检测方法。方差分析结果显示MC3R基因型显著影响公鸡和母鸡的体重,以及公鸡腹脂含量。该结果建议MC3R基因可以作为侯选基因解释杂交鸡体重显著差异的原因。     

中国人诱导型一氧化氮合酶基因STR多态性研究

一氧化氮（nitric oxide,NO）作为一种可在细胞间自由扩散的信使分子在神经递质传递和血管舒张调节等生理与病理过程中起着重要作用。NO通过一氧化氮合酶（nitric oxide synthase,NOS）催化L-精氨酸的氧化反应而生成。目前在哺乳动物中已发现细胞来源、表达方式和活性调节不同的3种NOS同工酶,分别为神经原型NOS(meuronal NOS,nNOS）、诱导型NOS(inducible NOS,iNOS）和内皮细胞型NOS（endothelial NOS,eNOS）。3种NOS由位于不同染色体上的基因所编码。人iNOS基因位于第17号染色体长臂(17q11.2～17q12）,全长约37kb,含有26个外显子,iNOS可在多种类型的细胞中通过IL-1、IFN-a、INF-γ等细胞因子和其他介质的刺激作用而诱导表达。iNOS基因5‘-端调控区内存在一个CCTTT串联重复的多态性位点,这一多态性基因座已居北爱尔兰的糖尿病患者中证实与微血管病变有关。另有实验表明,CCTTT串联重复序列的变化对iNOS基因的转录将产生不同影响。目前在东方种族中有关iNOS基因CCTTT串联重复多态性尚未见报道。将303名中国汉族人基因组DNA用于iNOS基因CCTTT串联重复多态性分析,鉴定出了12种等位基因和49种基因型,其中重复17次、18次和19次的等位基因是在人类中首次发现的新等位基因。统计学检验和比较表明,中国汉族人iNOS基因CCTTT串联重复序列的6个等位基因频率与来自英格兰的高加索人差异显著,说明这一多态性位点的等位基因频率分布存在种族差异。在中国正常人群中获得的有关iNOS基因STR多态性的统计资料,对于进一步研究这一多态性基因座与心脑血管疾病的相关性将有重要应用价值。     

New anonymous nuclear DNA markers for the pearl oyster Pinctada margaritifera and other Pinctada species

The black‐lipped oyster Pinctada margaritifera is highly exploited in French Polynesia where the pearl industry relies mostly on spat collection, and therefore on resources available in the wild. Little is known of these resources, and population genetic studies would be useful to improve management. We used two methods, direct amplification of length polymorphism (DALP) and exon primed intron crossing (EPIC) to develop five new nuclear markers presenting length polymorphism. Although these markers remained anonymous after using blast on GenBank, they are codominant and follow Hardy–Weinberg equilibrium. Tests on related species or subspecies of Pinctada gave encouraging results.     

Isolation and characterization of microsatellite DNA markers in the malaria vector Anopheles funestus

Screening of the Anopheles funestus genomic DNA library detected 18 new sequences with dinucleotide tandem repeats. Primers were designed to amplify the loci and 14 out of 18 gave a repeatable and scorable amplification. Deviations from Hardy–Weinberg expectations were tested for each locus in a sample of 30 wild Anopheles funestus females. No heterozygote deficiency was detected for 11 loci of 14, thus revealing the absence of null alleles. The number of alleles per locus ranged from 5 to 15, and observed heterozygosity from 0.13 to 0.85.