Isozyme, ISSR and RAPD profiling of genotypes in marvel grass (Dichanthium annulatum)

Genetic analysis of 30 accessions of marvel grass (Dichanthium annulatum Forsk.), a tropical range grass collected from grasslands and open fields of drier regions, was carried out with the objectives of identifying unique materials that could be used in developing the core germplasm for such regions as well as to explore gene (s) for drought tolerance. Five inter-simple sequence repeat (ISSR) primers [(CA)4, (AGAC), (GACA) 4; 27 random amplified polymorphic DNA (RAPD) and four enzyme systems were employed in the present study. In total, ISSR yielded 61 (52 polymorphic), RAPD 269 (253 polymorphic) and enzyme 55 isozymes (44 polymorphic) bands. The average polymorphic information content (PIC) and marker index (MI) across all polymorphic bands of 3 markers systems ranged from 0.419 to 0.480 and 4.34 to 5.25 respectively Dendrogram analysis revealed three main clusters with all three markers. Four enzymes namely esterase (EST), polyphenoloxidase (PPO), peroxidase (PRX) and superoxide dismutase (SOD) revealed 55 alleles from a total of 16 enzyme-coding loci. Of these, 14 loci and 44 alleles were polymorphic. The mean number of alleles per locus was 3.43. Mean heterozygosity observed among the polymorphic loci ranged from 0.406 (SOD) to 0.836 (EST) and accession wise from 0.679 (1G3108) to 0.743 (IGKMD-10). Though there was intermixing of few accessions of one agro-climatic region to another largely groupings of accessions were with their regions of collections. Bootstrap analysis at 1000 iterations also showed large numbers of nodes (11 to 17) having strong clustering (> 50 bootstrap values) in all three marker systems. The accessions of the arid and drier regions forming one cluster are assigned as distinct core collection of Dichanthium and can be targeted for isolation of gene (s) for drought tolerance. Variations in isozyme allele numbers and high PIC (0.48) and MI (4.98) as observed with ISSR markers indicated their usefulness for germplasm characterization.     

Relationship of Breeding System to Rarity in the Lakeside Daisy (Hymenoxys acaulis var. glabra)

The breeding system of a rare Great Lakes endemic, the lakeside daisy ( Hymenoxys acaulis var. glabra ), was investigated when plants from a remnant Illinois population produced no seeds for over 15 years. To determine if the Lakeside daisy was self-incompatible, 20 plants from two populations, Illinois and Ohio, were selfed and outcrossed. Seed/ovule ratios were compared among the different treatments and the location of the incompatibility reaction was identified. Lakeside daisy was found to be self-incompatible (sporophytic). The last Illinois population was effectively extinct because the remaining plants belonged to the same mating type ( N _e = 1) and only produced seeds when outcrossed to the Ohio plants. Cross-incompatibility was also observed among Ohio plants, suggesting that within large populations, compatible mating types may be rare locally. In addition, inbreeding depression (lower seed/ovule ratios in inbred than in outcrosses) was observed after one generation of inbreeding. Small populations of self-incompatible species are vulnerable to extinction if the number of self-incompatibility alleles, either as a result of a bottleneck or of genetic drift, falls below tbe number needed for the breeding system to function. Recovery protocols based on these genetic considerations were developed and implemented in 1988 when Lakeside daisy populations were established at three Illinois nature preserves.     

Cd对河南华溪蟹(Sinopotamon henanense)主要组织器官SOD和POD同工酶的影响

采用聚丙烯酰胺凝胶电泳(PAGE)的方法,研究了5种浓度的镉(Cd:7.25,14.5,29,58,116mg/L)对河南华溪蟹(Sinopotamonhenanense)肝胰腺、鳃和心脏中超氧化物歧化酶(SOD)和过氧化物酶(POD)同工酶的影响。结果显示,在实验剂量范围内,随着Cd浓度的增加,肝胰腺和鳃中SOD同工酶和POD同工酶有显著的变化,包括新酶带的出现和酶带强度的变化.Cd对肝胰腺和鳃中SOD同工酶具有明显的激活效应,但是对POD同工酶却有抑制作用.Cd对心脏中SOD同工酶的影响不明显,基本没有变化,但却可以抑制POD同工酶的相对活性,包括酶带数和酶带强度的变化.表明SOD和POD同工酶的变化可以灵敏地反映Cd对河南华溪蟹的胁迫程度及毒性大小.     

长柄石杉居群遗传多样性和遗传结构的AFLP分析

石杉科植物因所含石杉碱甲(Huperzine A)对中老年痴呆等具有良好疗效,近年来倍受关注.利用AFLP分子标记对武夷山脉广布种长柄石杉[Huperzia serrata(Thunb.ex Murray)Trev.var.longipetiolata(Spring)H.M.Chang]7个居群112株个体进行遗传多样性和居群遗传结构分析.选用多态性高、分辨力强的8对选择性扩增引物组合共获得675个位点,其中多态位点比例为69.38%.居群内观测等位基因数(Na)为1.633,有效等位基因数(Ne)1.493;Nei’s基因多样性指数(He)与Shannon多态性信息指数(I)的平均值分别为0.272和0.392,多样性最高为地处武夷山脉中段的泰宁居群和建宁居群,最低为山脉北段的光泽居群.居群总基因多样性(Ht)为0.327 3,居群内基因多样性(Hs)为0.272 2,居群间的遗传分化系数(Gst)为0.168 1,表明居群内变异是长柄石杉遗传多样性的主要来源.由Gst估计,武夷山脉长柄石杉自然居群的基因流(Nm)为2.474 0.邻接树分析表明居群间遗传亲缘关系与地理位置相关.武夷山脉长柄石杉较高的遗传多样性和基因流水平表明其仍然具有相当的适应(生存)能力和进化潜力,这可能与其生物学(异交水平)、生态学特性及武夷山脉相对良好的生境条件有关.     

Clutch size and the cost of incubation in the Bengalese finch (Lonchura striata var. domestica)

Summary By measuring daily intake of food, we compared the cost of incubation for small and large clutches in adult Bengalese finches (Lonchura striata var. domestica). Natural clutches of captive finches were experimentally manipulated to produce two egg or six egg clutches. While incubating large clutches, parents ate significantly more food and took longer to hatch their first egg than did the same birds when provided with small clutches. This supports the hypothesis that the cost of incubation increases with clutch size. This cost should influence other energy allocation decisions in birds such as determination of clutch size and parental investment decisions.     

Genetic Analysis of the Endangered Island Endemic Malacothamnus fasciculatus (Nutt.) Greene var. nesioticus (Rob.) Kearn. (Malvaceae)

Isozyme, randomly amplified polymorphic DNA, and ribosomal DNA analyses were used to evaluate the genetic distinctness and diversity of the endangered island endemic Malacothamnus fasciculatus var. nesioticus (Santa Cruz Island bush mallow). Analysis of amplified DNA profiles and electrophoretic data indicates that var. nesioticus is genetically distinct from other varieties within the species. No isozyme or amplified DNA variation was detected among individuals of nesioticus populations, but restriction site analysis of ribosomal DNA revealed the presence of three closely related genotypes within one of the nesioticus populations. Apparent clonal structuring was found in both nesioticus populations and in one mainland population, var. nuttallli . Results from these analyses provide the background necessary for the design of conservation efforts with recovery goals that insure the long-term survival of Malacothamnus fasciculatus var. nesioticus .     

Ultrastructure of tetrasporogenesis in the red alga Osmundea spectabilis var. spectabilis (Rhodomelaceae: Ceramiales: Rhodophyta)

Tetrasporogenesis in Osmundea spectabilis (Postels and Ruprecht) K.W. Nam var. spectabilis proceeds through three developmental stages. A uninucleate tetraspore mother cell with synaptonemal complexes depicted during early prophase of meiosis I comprises the youngest stage. Subsequently, the nuclear envelope obtains a highly irregular profile and is surrounded by perinuclear endoplasmic reticulum (ER) and numerous mitochondria. Proplastids with peripheral thylakoid and numerous straight-profiled dictyosomes are present. Dictyosome vesicles discharge their contents, initiating tetraspore wall formation. A four-nucleate tetraspore mother cell is formed prior to tetrahedral cleavage. During the second stage of tetraspore formation the nuclei are very irregular in outline and move toward the central region where they fuse. The formation of fibrous vacuoles originates from the fibrous vacuole associated organelles (FVAOs). Thylakoid formation from concentric lamellar bodies (CLBs) seems to occur in plastids. Extremely hypertrophied dictyosomes with two tightly compressed and densely laminated mid-regions produce vesicles which contribute to enlargement of the fibrous vacuoles. During the second stage of tetraspore development striated vesicles are formed and starch granule formation increases. Mature tetraspores are characterized by numerous cored vesicles and abundant starch granules. Plastids have a fully developed system of internal thylakoids, and cleavage is usually complete at this stage. Mature tetraspores are surrounded by a bi-layered wall and the tetrasporangial wall. Unbranched, tubular structures connecting the plasmalemma with the peripheral sheets of ER are possibly involved in wall deformation. A distinct blebbing nuclear envelope appears to sequester vesicles into the cytoplasm.     

Abundance and production rates of floating diatom mats (Rhizosolenia castracanei and R. imbricata var. shrubsolei) in the Eastern Pacific Ocean

Abundance and production rates were measured on freefloating mats composed of the diatoms Rhizosolenia castracanei and R. imbricata var. shrubsolei in the California Current and boundary waters of the central North Pacific during October, 1980. Mats ranged from 3.0 to 10.6 cm in maximum length and had a mean volume of 6.4 ml. Production rates of the diatom mats averaged 4.0 g C colony^-1 h^-1, more than 10³ times higher than that of an equal volume of surrounding water. However, because of their low density at these sites, about 1 mat m^-3, diatom mats contributed only about 1% of the total primary production. The two large Rhizosolenia species comprised almost all of the phytoplankton biomass within the mats. Rhizosolenia species rarely occurred in seawater between mats, where the phytoplankton community was dominated by a diverse array of nannoplankton. The Rhizosolenia species in the mats appeared to be in healthy condition and contained intracellular bacteria. The very high production rates of the colonies indicate high nutrient demand and, since these particular diatoms lack the symbiotic cyanobacterium Richelia intracellularis, which is implicated in N-fixation in other species of Rhizosolenia, our results indicate that other nutrient sources must be present. We discuss the potential role of the intracellular bacteria in nitrogen fixation.     

Quantitative and Molecular Genetic Variation in Captive Cotton-Top Tamarins (Saguinus oedipus)

Most genetic surveys of captive and endangered populations are carried out with single gene characters bearing no direct relationship to life history or other features for which genetic variation needs to be maintained. Quantitative genetic estimates of heritable variation for life-history traits may be a more direct and appropriate measure of genetic variation for some conservation purposes. Furthermore, recent theoretical and empirical results indicate that genetic variation measured on these two levels may not be concordant. We analyzed heterozygosity at 41 allozyme loci and heritability for body weight in captive cotton-top tamarins ( Saguinus oedipus ) from the Marmoset Research Center of the Oak Ridge Associated Universities in order to compare these two levels of genetic variation. Cotton-top tamarins are a highly endangered species native to Colombia. Many animals currently reside in research facilities and zoological parks. A total of 106 animals were used in the isozyme survey, while data on 364 animals contributed to the quantitative genetic study of body weight. We found a very low average heterozygosity ( H = 1%) for this colony. Body weight was moderately and significantly heritable ( h ² = 35%). This heritability is within the normal range for natural animal populations. The finding of biologically significant levels of heritability in a population with abnormally low allozyme heterozygosity illustrates the point that low levels of allozyme heterozygosity should not be taken as an indication of overall lack of genetic variation in important quantitative characters such as life-history traits. Genetic variation required for adaptation of species to future environmental challenges can exist despite low levels of enzyme heterozygosity.     

厦门市PM10浓度空间与时间差异分析

在厦门市环境大气污染物中,PM10是其首要的大气污染物。厦门市大气中的PM10浓度受天气和气候以及土地利用类型、交通排放、工业状况等诸多自然因素和人为因素的共同影响而呈现出一定的时空变化规律,文章对厦门市2001年至2002年PM10浓度的空间变化和时间变化特点进行了分析,揭示了影响厦门市环境大气中PM10浓度空间变化和不同尺度的时间变化的影响因素。     

Social relationships among adult female baboons (papio cynocephalus) I. Variation in the strength of social bonds

Sociality has positive effects on female fitness in many mammalian species. Among female baboons, those who are most socially integrated reproduce most successfully. Here we test a number of predictions derived from kin selection theory about the strength of social bonds among adult female baboons. Our analyses are based on systematic observations of grooming and association patterns among 118 females living in seven different social groups in the Amboseli Basin of Kenya over a 16-year period. Females in these groups formed the strongest bonds with close kin, including their mothers, daughters, and maternal and paternal sisters. Females were also strongly attracted toward females who were close to their own age, perhaps because peers were often paternal sisters. Females’ bonds with their maternal sisters were strengthened after their mother’s deaths, whereas their relationships with their maternal aunts were weakened after their mother’s death. In addition, females formed stronger bonds with their paternal sisters when no close maternal kin were available, and they compensated for the absence of any close kin by forming strong bonds with nonrelatives. Taken together, these data suggest that social bonds play a vital role in females’ lives, and the ability to establish and maintain strong social bonds may have important fitness consequences for females.Joan B. Silk is on sabbatical at Cambridge University from September 2005 to August 2006. Tel.: +44-7929759697; Fax: +44-1223-335460.     

Phylogeographic Subspecies Recognition in Leopards (Panthera pardus): Molecular Genetic Variation

The incorporation of precise definitions for taxonomic units into wildlife legislation has necessitated the reevaluation of the taxonomy of endangered and threatened species. We used the subspecies recognition criteria proposed by Avise and Ball (1990) and O'Brien and Mayr (1991) to examine the infraspecific taxonomy of the leopard, Panthera pardus , a geographically widespread species with 27 currently recognized trinomial designations. Samples from named subspecies revealed appreciable genetic diversity using three molecular methods: allozymes, mitochondrial DNA restriction sites, and feline-specific minisatellites. Continental populations and subspecies from Africa and Asia possessed the highest amount of molecular genetic variation, whereas relatively lower amounts of diversity were present in island populations. Molecular data were analyzed using three phylogenetic methods (distance-matrix, maximum parsimony, and maximum likelihood) to resolve genetic differentiation below the species level The combined results revealed phylogenetic distinction of six geographically isolated groups of leopards: (1) African, (2) central Asian, (3) Indian, (4) Sri Lankan, (5) Javan, and (6) east Asian. Based on the combined molecular analyses and supporting morphological data (Miththapala 1992), u,e recommend that subspecific leopard taxonomy be revised to comprise eight subspecies: (1) P. p. pardus , Africa; (2) P. p. saxicolor , central Asia; (3) P. p. fusca , Indian subcontinent; (4) P. p. kotiya , Sri Lanka; (5) P. p. melas , Java; (6) P. p. orientalis , Amur; (7) P. p. japonensis , northern China; and (8) P. p. delacouri , southern China. In most cases, designated subspecies conform to historic geological barriers that would have facilitated allopatric genetic divergence.     

Variation in copulation duration in Mnais pruinosa pruinosa Selys (Odonata: Calopterygidae)

Summary The Japanese calopterygid damselfly Mnais pruinosa pruinosa shows three distinct copulation durations (Siva-Jothy and Tsubaki 1989). A variety of factors which might influence copulation duration were investigated. Results indicate that the temperature in the vicinity of copulating pairs, the rate at which males encountered receptive females, territory quality, the rate of agonistic interactions between males, female gravidity and female willingness to oviposit have no effect on copulation duration. The most significant factor was the location of the site at which males captured their mates. We suggest that under natural conditions the location of the capture site provides males with reliable, indirect information about a female's intention to oviposit: it is important for males of this species to acquire such information since sperm precedence, and therefore reproductive success, is in part dependant on the interval experienced by females between copulation and subsequent oviposition. The results are discussed and it is suggested that the three observed mate-securing tactics of M.p. pruinosa are facultative and information-dependant.     

Variation in copulation duration in Mnais pruinosa pruinosa Selys (Odonata: Calopterygidae)

Summary Males of the damselfly Mnais pruinosa pruinosa were observed to use three different tactics to secure mates. The mean duration of copulation differed between the three observed tatics and resulted in varying degrees of sperm removal and insemination. It is shown that the last male to mate had almost 100% sperm precedence immediately after copulation regardless of the duration of copulation and therefore the quantity of sperm removed. In situations where less than 100% of rivals' sperm was removed the sperm from different males mixed within the female sperm storage organs over a period of about 6 days: sperm mixing produced variation in last male sperm precedence. The significance of sperm mixing in M. p. pruinosa is discussed in the context of the observed matesecuring tactics and the frequent female habit (37% of observations) of ovipositing without remating during an oviposition bout.     

贵阳市郊菜园土-辣椒体系中重金属的迁移特征

选择贵阳市郊二戈寨、马铃乡和永乐乡的辣椒地,研究重金属在菜园土-辣椒体系中的迁移过程.结果表明,二戈寨、马铃乡和永乐乡3处采样地点菜园土中存在不同程度的重金属污染,综合污染指数分别为1.17、1.23和2.18,主要污染元素为Zn、Cu、Cd.但辣椒果实中仅有Cd超标.在土壤-辣椒体系各界面间,重金属元素迁移能力大小顺序发生了变化:在土壤-根部间为CdCu＞Zn＞Pb,在根部-茎叶间为Zn＞Cd＞Pb＞Cu,在茎叶-果实间为Cu(＞＞)Zn＞Cd＞Pb.对于Cu、Pb和Zn元素来说,辣椒根-土界面是重金属进入辣椒果实的主要障碍,其生物富集系数BCF值(蔬菜根中重金属含量/土壤中重金属含量)分别在0.21～0.44、0.04～0.24和0.033～0.08之间,而Cd的BCF值却达1.06～4.23,表现为富集作用.Cd的迁移系数TF1值(蔬菜茎叶中重金属含量/根部重金属含量)表明,其在根部-茎叶间的迁移几乎不受阻碍,但在果实-茎叶界面再次受阻,其TF2值(蔬菜果实中重金属含量/茎叶中重金属含量)在0.42～0.51之间.     

Mitochondrial DNA Variation in Black Rhinoceros (Diceros bicornis): Conservation Management Implications

Cell cultures have been established from 33 individual black rhinoceroses. These were from wild populations from various localities in southern Africa and include representatives from three geographical regions (southwestern, south-central, and eastern) corresponding to currently accepted conservation units, and include individuals previously attributed to one of the four subspecies, Diceros b. minor, D. b. bicornis, D. b. michaeli , and D. b. chobiensis (du Toit et al. 1987). Comparative mitochondrial DNA restriction maps were constructed using 16 restriction enzymes. These showed in each case two site differences between representative individuals from any two of the above geographical regions. Maps were monomorphic within geographical regions and, therefore, have the potential to provide diagnostic markers. The map from a single individual attributed to the D. b. chobiensis subspecies was identical to other individuals (attributed to D. b. minor ) in the south-central geographical region. The low amount of genetic diversity implied by these few differences renders it unlikely that problems with outbreeding depression will arise if, given the continuing decline in numbers of black rhinoceroses, it becomes necessary to supplement wild or captive populations with individuals from a different conservation unit in order to avoid inbreeding depression.     

利用发光细菌测试方法评价菲和芘生物降解过程的毒性变化

将发光细菌毒性测试方法应用于典型多环芳烃生物降解过程的毒性评价,研究了菲和芘单独及混合状态下生物降解过程中的毒性变化。结果表明:溶解态的菲和芘在一定浓度范围内对发光细菌均具有毒性,菲和芘对发光细菌的10 min-EC50值分别为1.61×10-5mol·L-1和2.31×10-6mol·L-1。单组分和混合组分的菲和芘经过微生物降解后,其毒性显著降低。混合组分生物降解体系中由于菲和芘分子之间的互相作用,使其对发光细菌的毒性效应与其单独存在时有差异。生物降解的各阶段,混合组分降解体系的毒性均大于单组分菲或芘降解体系的毒性,且在降解完全的后期,培养液的毒性有增加的趋势。这与菲和芘降解中间产物的积累变化有关。