Parentage assignment in hatchery population of brown sole <Emphasis Type="Italic">Pleuronectes herzensteini</Emphasis> by microsatellite DNA markers

ABSTRACT:   Five loci ( Phz2 , Phz6 , Phz7 , Phz12 , and Phz14 ) of microsatellite DNA markers developed in a previous study for parentage assignment in the hatchery population generated by mating among 61 broodstock fish (35 females and 26 males) in a spawning tank, were selected. After natural spawning in the same tank, larvae collected at three different times were categorized into early phase (EP), middle phase (MP), and late phase (LP) groups. In the parental broodstock, the mean number of alleles per locus was 21.8 and expected heterozygosity ( H _E ) was 0.813. In the progeny, the mean number of alleles per locus decreased to 11.6 (EP), 14.4 (MP), and 6.4 (LP) and H _E to 0.796 (EP), 0.833 (MP), and 0.681 (LP). Parental assignment determined eight dams and six sires as major parents for the EP group. In the MP group, 13 dams and ten sires genetically contributed to spawning, but only three dams and two sires were involved in LP group progeny. In the hatchery population produced from a limited number of parental fish such as the LP group, genetic variability was apparently decreased.     

EM原露在番茄无土栽培上的应用试验

以番茄豫艺红将军为试材,在连栋温室无土栽培环境下,进行了EM原露对番茄生长与产量影响的研究。结果表明,EM原露对番茄生长和产量的提高有着显著促进作用,并随施用量的增加而增加。     

Conservation genetic assessment of the paleback darter,Etheostoma pallididorsum,a narrowly distributed endemic in the Ouachita Highlands,Arkansas, USA

1. The paleback darter, Etheostoma pallididorsum, is considered imperilled and has recently been petitioned for listing under the Endangered Species Act. Previous allozyme-based studies found evidence of a small effective population size, warranting conservation concern. The objective of this study was to assess the population dynamics and the phylogeographical history of the paleback darter, using a multilocus microsatellite approach and mitochondrial DNA.
2. The predictions of this study were that: paleback darter populations will exhibit low genetic diversity and minimal gene flow; population structure will correspond to the river systems from which the samples are derived; reservoir dams impounding the reaches between the Caddo and Ouachita rivers would serve as effective barriers to gene flow; and the Caddo and Ouachita rivers are reciprocally monophyletic.
3. Microsatellite DNA loci revealed significant structure among sampled localities (global F_st = 0.17, P < 0.001), with evidence of two distinct populations representing the Caddo and Ouachita rivers. However, Bayesian phylogeographical analyses resulted in three distinct clades: Caddo River, Ouachita River, and Mazarn Creek. Divergence from the most recent ancestor shared among the river drainages was estimated at 60 Kya. Population genetic diversity was relatively low (H_e = 0.65; mean alleles per locus, A = 6.26), but was comparable with the population genetic diversity found in the close relatives slackwater darter, Etheostoma boschungi (H_e = 0.65; A = 6.74), and Tuscumbia darter, Etheostoma tuscumbia (H_e = 0.57; A = 5.53).
4. These results have conservation implications for paleback darter populations and can be informative for other headwater specialist species. Like other headwater species with population structuring and relatively low genetic diversity, the persistence of paleback darter populations is likely to be tied to the persistence and connectivity of local breeding and non-breeding habitat. These results do not raise conservation concern for a population decline; however, the restricted distribution and endemic status of the species still renders paleback darter populations vulnerable to extirpation or extinction.

     

体外培养条件下三角帆蚌胚胎早期发育观察及胚胎发育生物学零度和有效积温分析

为了探寻三角帆蚌胚胎体外培养方法,本实验以解剖获得的雌雄配子为材料,使用与三角帆蚌体液等渗的平衡盐溶液(BSS)进行人工体外受精和体外培养,观察各阶段胚胎的形态特征,并分析计算不同胚胎发育阶段的生物学零度和有效积温。结果显示,在温度为(25±1)℃的BSS培养条件下,受精卵发育至第二极体排放、二细胞期、四细胞期、八细胞期、十六细胞期和桑葚期的时间分别为1.8、2.8、5.6、10.5、13.9和17.3 h,胚胎最长发育至桑葚期后停止发育。另外,池塘平均水温分别为26.5、28.1和29.2℃时,三角帆蚌胚胎发育至成熟钩介幼虫分别需要10、9和8 d,计算得出三角帆蚌胚胎发育的生物学零度为14.81℃,根据生物学零度计算胚胎发育至卵裂期、囊胚期、原肠期、膜内钩介幼虫期和成熟钩介幼虫的有效积温分别为12.95、25.99、42.27、69.21和118.14℃×d。研究结果初步尝试对三角帆蚌受精卵进行体外培养,并根据胚胎发育水温和时间获得三角帆蚌早期胚胎发育的生物学零度和有效积温,可为突破三角帆蚌全人工繁育技术奠定基础,对淡水贝类现代生物育种技术研发和种质资源保护具有重要意义。     

温度对玫瑰无须鲃胚胎发育的影响

为了探索温度对玫瑰无须鲃(Puntius conchonius)胚胎发育的影响,将玫瑰无须鲃的受精卵置于不同温度培养容器中进行孵化观察。结果显示,在温度为18～32℃的环境条件下,玫瑰无须鲃的胚胎均能孵化,最适孵化温度范围为24～28℃。如果温度高于32℃或低于18℃时,玫瑰无须鲃的胚胎不能孵出仔鱼。在温度为34℃时,胚胎发育到原肠胚晚期全部死亡,温度为16℃时,胚胎发育停止于神经胚期,孵化时间随温度的升高而缩短,呈幂函数相关。玫瑰无须鲃胚胎发育的生物学零度为12.35℃,有效积温为419.40℃.h。     

Convective Drying Kinetics and Physical Properties of Silver Carp (Hypophthalmichthys molitrix) Fillets

The aim of this work was to investigate drying kinetics of silver carp fillets at the temperatures of 40, 50, 60, and 70°C for two air velocities (0.5 and 1.5 m/s) and to evaluate the effect of drying temperature on the physical properties of the products. From regression analysis of the experimental data, a Two-term model was found to adequately predict the drying process at all conditions tested. Effective moisture diffusivities (D_eff) ranged between 2.47?×?10^?10 m²/s and 5.98?×?10^?10m²/s and increased with temperature and air velocity. Rehydration ratio, hardness, and springiness were significantly affected by drying temperature. Color parameters, except b*, showed no dependence on temperature.     

Pedigree analysis in the Brazilian Zebu breeds

Zebu breeds play an important role in cattle production systems in Brazil. To assess the genetic variability from animals in the Herd Books of Nelore, Gir and Guzerat breeds, generation intervals, inbreeding, effective population size and parameters of gene origin (effective number of founders, ancestors and founder genomes) were calculated using pedigree records from 1938 to 1998. Breed subdivision was quantified by Wright's F -statistics. Calculations were separately carried out for consecutive 4-year intervals in the period 1979–98. Generation interval was around 8 years for the three breeds. Total inbreeding increased in all the breeds reaching values of 2.13%, 2.28% and 1.75%. Effective population size decreased from 85 to 68 in Nelore, from 70 to 45 in Gir and remained nearly constant around 104 in Guzerat. The quantities assessing the number of contributing ancestors decreased with time in all the breeds, and in the last analysed period the most important ancestor accounted for 14%, 3.1% and 4.1% in Nelore, Gir and Guzerat, respectively. Results indicate that the studied breeds are suffering from a loss of genetic variability which can result in negative effects on breeding and conservation purposes.     

温度对花绒寄甲发育和生殖的影响

花绒寄甲Dastarcus helophoroides（Fairmaire）是寄生栗山天牛Massicus raddei（Blessig）、云斑天牛Batocera lineolata Chevrolat、松褐天牛Monochamus alternatus Hope、光肩星天牛Anoplophora glabripennis（Motschulsky）、锈色粒肩天牛Apriona swainsoni（Hope）等多种我国重大蛀干害虫天牛的主要天敌。为大量繁殖花绒寄甲防治天牛,本研究测定了花绒寄甲发育和生殖与温度的关系,包括卵期、幼虫期和蛹期的发育起点温度和有效积温;并研究在营养欠缺条件下不同温度处理成虫死亡率达50%时的天数,以及饲料供给充足状态下成虫的产卵量。结果表明,花绒寄甲卵期发育与温度的关系符合幂指数模型,发育起点温度和有效积温分别为12.80℃和126.09日度;幼虫期和蛹期发育与温度的关系符合抛物线型,发育起点温度和有效积温分别为11.7℃、139.0日度和13.9℃、265.24日度。在16～19℃、营养缺乏条件下,成虫死亡率达50%的时间为62～63 d,表明该天敌具有较强的耐饥力。在22～25℃、食料供给充分条件下,成虫产卵量最大,人工大量繁殖和饲养花绒寄甲的最适温度为22℃。只要食料充分,花绒寄甲成虫在所有温度处理下的寿命均达4年以上。     

3类功能助剂对酥梨的安全性及其对重要害虫防效的影响

为明确3类不同功能助剂在酥梨园的安全使用技术及其对梨园重要害虫防效的影响,在田间梨树不同发育期,调查3类、共6种功能助剂对果实和叶片的药害率;调查3种安全助剂与4种农药混配后对梨小食心虫和梨木虱的防效.结果表明,6种功能助剂对梨果药害率从高到低依次为15 d幼果、45 d小果和75 d膨大期果实;6种助剂对叶片均安全....