HERITABLE VARIATION IN RESOURCE UTILIZATION AND RESPONSE IN A WINERY POPULATION OF DROSOPHILA MELANOGASTER

It has been found that Drosophila melanogaster lines from the “Chateau Tahbilk” winery cellar had higher larval ethanol resistance than lines originating from outside the cellar. Because the adaptive significance of this trait is unclear, we have reexamined genetic microdifferentiation at Tahbilk with other resources and different tests for ethanol adaptation. Cellar stocks tended to be more resistant to starvation after exposure to wine seepage than stocks originating from orchard traps outside the cellar. Lines from a grape residue pile were also more resistant to starvation after seepage exposure than orchard stocks even though these collection sites were a few meters apart. Cellar and orchard stocks did not differ in ethanol resistance as measured by larval viability tests on low sucrose medium. However, stocks from the grape residue pile showed an increase in adult longevity over ethanol vapor compared to those from the cellar or orchard stocks. These differences were not due to maternal effects. In laboratory tests of behavioral responses, cellar stocks were relatively more attracted to seepage than orchard stocks in one year but not in the other two years. The findings suggest some adaptive differentiation related to resource heterogeneity at Tahbilk.     

Trypanosoma cruzi: Impact of dual-clone infections on parasite biological properties in BALB/c mice

Herein, we have analyzed major biological properties following dual-clone Trypanosoma cruzi infections in BALB/c mice. Eight T. cruzi clonal stocks, two of each principal genotype, including genotype 19 and 20 (T. cruzi I), hybrid genotype 39 (T. cruzi) and 32 (T. cruzi II) were combined into 24 different dual-clone infections. Special attention was given to characterize biological parameters assayed including: prepatent period, patent period, maximum of parasitemia, day of maximum parasitemia, area under the parasitemia curve, infectivity, mortality, and hemoculture positivity. Our findings clearly demonstrated that features resultant of dual-clone infections of T. cruzi clonal stocks did not display either the characteristics of the corresponding monoclonal infections or the theoretical mixture based on the respective monoclonal infections. Significant changes in the expected values were observed in 4.2-79.2% of the mixtures considering the eight biological parameters studied. A lower frequency of significant differences was found for mixtures composed by phylogenetically distant clonal stocks. Altogether, our data support our hypothesis that mixed T. cruzi infections have a great impact on the biological properties of the parasite in the host and re-emphasizes the importance of considering the possible occurrence of natural mixed infections in humans and their consequences on the biological aspects of ongoing Chagas' disease.     

中国沿海日本鳗鲡幼苗群体鉴别研究

本文研究了中国沿海日本鳗鲡Anguilla japanica Temminck et Schlegel幼苗的群体问题。通过各项形态性状的观察、计量和差异统计比较,结合有关资料进行了综合分析。所得结果表明:我国沿海主要鳗苗产区的群体,相互间存在着一定的关系,均属同一个种、同一个种群,惟作为今后渔业资源管理的基本单元,其间尚可区分出江苏、长江口、浙江、福建、广东等若干不同的群体。     

Patterns and predictors of soil organic carbon storage across a continental-scale network

The rarity of rapid campaigns to characterize soils across scales limits opportunities to investigate variation in soil carbon stocks (SOC) storage simultaneously at large and small scales, with and without site-level replication. We used data from two complementary campaigns at 40 sites in the United States across the National Ecological Observatory Network (NEON), in which one campaign sampled profiles from closely co-located intensive plots and physically composited similar horizons, and the other sampled dozens of pedons across the landscape at each site. We demonstrate some consistencies between these distinct designs, while also revealing that within-site replication reveals patterns and predictors of SOC stocks not detectable with non-replicated designs. Both designs demonstrate that SOC stocks of whole soil profiles vary across continental-scale climate gradients. However, broad climate patterns may mask the importance of localized variation in soil physicochemical properties, as captured by within-site sampling, especially for SOC stocks of discrete genetic horizons. Within-site replication also reveals examples in which expectations based on readily explained continental-scale patterns do not hold. For example, even wide-ranging drainage class sequences within landscapes do not duplicate the clear differences in profile SOC stocks across drainage classes at the continental scale, and physicochemical factors associated with increasing B horizon SOC stocks at continental scales frequently do not follow the same patterns within landscapes. Because inferences from SOC studies are a product of their context (where, when, how), this study provides context—in terms of SOC stocks and the factors that influence them—for others assessing soils and the C cycle at NEON sites.

     

Stock differences in the susceptibility of rats to learned helplessness training

Learned helplessness (LH) consists of shock escape deficits evidenced by animals previously exposed to inescapable shock. This phenomenon has shown promise as a behavioral screen for new antidepressant drugs. Unfortunately, some stocks of rats evidence low susceptibility to LH training. Accordingly, male rats from 8 different stocks were tested for susceptibility to LH training. The outbred stocks consisted of Harlan SD, Sasco Holtzman, and Charles River Holtzman. The inbred stocks (i.e. strains) tested were Lewis, Wistar Kyoto, Brown Norway, Fischer F-344, and Buffalo. The Lewis, Brown Norway, Fischer and Sasco Holtzman rats were found to be virtually non-susceptible to LH training. Harlan SD and Buffalo rats evidenced intermediate susceptibilities of 28% and 33%, respectively. Kyoto and Charles River Holtzman rats were the most susceptible at 53% and 55%, respectively. No stock differences between control animals were observed. These results indicate that wide differences in susceptibility to LH training exist in rats from different stocks or suppliers and researchers should be careful to choose subjects from a susceptible stock. Charles River Holtzman and Wistar Kyoto rats appear to be very susceptible to LH training.     

Observations on the antigenicity and serological relationships of stocks of Trypanosoma congolense from East and West Africa.

Antigenic relationships of 4 stocks of Trypanosoma congolense from different parts of Africa were examined by immunofluorescence (IFAT) and neutralization tests. Antisera to each stock were obtained from rabbits infected with trypanosomes transmitted by Glossina morsitans. Trypanosomes for use as antigens were obtained from local skin reactions developing on rabbits infected with 2 of the stocks. Using the IFAT and antisera at end-point dilutions approximately 40% of the trypanosomes fluoresced strongly and a further 30% less intensely with homologous antisera, indicating antigenic heterogeneity among the trypanosomes developing in the skin. Using antisera at low dilutions some samples gave cross-reactions with trypanosomes of heterologous stocks, but at higher dilutions there were no cross-reactions with either of the antigens. The lack of cross-reactions at high antiserum dilutions was interpreted as indicating antigenic differences between the 4 trypanosome stocks. Using neutralization tests only homologous antisera reduced the infectivity of trypanosome suspensions. Overall, these observations indicated that there were at least 3 different strains of T. congolense among the 4 stocks examined.     

Incidence of potato virus Y infection in seed and ware tubers of the potato cv. Record

The incidence of potato virus Y (PVY) infection was assessed in samples of potato tubers, cv. Record, taken from Scottish seed stocks and English ware crops grown from some of these seed stocks. PVY was readily detected by ELISA of tuber sprouts. PVY-infected tubers were found in 10 seed stocks of 84 tested. The mean level of virus infection was 0.23%, 0.76% and 0.56% in Super Elite, Elite and AA stocks respectively. In 46 commercial ware crops grown from some of these seed stocks, a substantial proportion of the harvested tubers in all but one of the crops were infected with PVY, the mean percentage of infected tubers was 58.5%. Ware crops grown from seven seed stocks in which PVY had been detected (mean 6.2% infection in seed) contained a mean of 70% infected tubers, compared with 56% infection in crops grown from 39 stocks in which PVY was not detected in the seed tubers. The predominant PVY strain detected in the ware crops was the veinal necrosis strain (PVY^vn).     

Comparative developmental biology of pink salmon, Oncorhynchus gorbuscha, in southern British Columbia

Eggs and alevins from 21 families of pink salmon, Oncorhynchus gorbuscha , from five odd-year broodline stocks spawning in southern British Columbia were incubated under controlled water temperatures of 4° C, 8° C and 12° C. There were significant differences in egg survival among stocks and among families within stocks at all incubation temperatures, but the differences were greatest at 4° C. Alevin survival was at least 97% for each stock at each temperature. The most northern spawning stocks had higher egg survival at 4° C than did the others. Hatching time of the alevins and emergence time of the fry were similar for all five stocks. Alevins hatching at 8° C were longer than those hatching at 4°C or 12°C, but there were no stock differences in alevin length or tissue weight. Stocks with larger eggs produced alevins of greater total weight and more yolk. Emergent fry from Vancouver Island stocks had the greatest tissue weight at 12° C, but Fraser River fry were heaviest at 8° C. There were significant differences among families within stocks for alevin and fry size parameters, suggesting that family variation should be accounted for in studies of salmonid developmental biology.     

Evaluation of Four Methods for Predicting Carbon Stocks of Korean Pine Plantations in Heilongjiang Province,China

A total of 89 trees of Korean pine (Pinus koraiensis) were destructively sampled from the plantations in Heilongjiang Province, P.R. China. The sample trees were measured and calculated for the biomass and carbon stocks of tree components (i.e., stem, branch, foliage and root). Both compatible biomass and carbon stock models were developed with the total biomass and total carbon stocks as the constraints, respectively. Four methods were used to evaluate the carbon stocks of tree components. The first method predicted carbon stocks directly by the compatible carbon stocks models (Method 1). The other three methods indirectly predicted the carbon stocks in two steps: (1) estimating the biomass by the compatible biomass models, and (2) multiplying the estimated biomass by three different carbon conversion factors (i.e., carbon conversion factor 0.5 (Method 2), average carbon concentration of the sample trees (Method 3), and average carbon concentration of each tree component (Method 4)). The prediction errors of estimating the carbon stocks were compared and tested for the differences between the four methods. The results showed that the compatible biomass and carbon models with tree diameter (D) as the sole independent variable performed well so that Method 1 was the best method for predicting the carbon stocks of tree components and total. There were significant differences among the four methods for the carbon stock of stem. Method 2 produced the largest error, especially for stem and total. Methods 3 and Method 4 were slightly worse than Method 1, but the differences were not statistically significant. In practice, the indirect method using the mean carbon concentration of individual trees was sufficient to obtain accurate carbon stocks estimation if carbon stocks models are not available.     

Production of Mucosally Transmissible SHIV Challenge Stocks from HIV-1 Circulating Recombinant Form 01_AE env Sequences

Simian-human immunodeficiency virus (SHIV) challenge stocks are critical for preclinical testing of vaccines, antibodies, and other interventions aimed to prevent HIV-1. A major unmet need for the field has been the lack of a SHIV challenge stock expressing circulating recombinant form 01_AE (CRF01_AE) env sequences. We therefore sought to develop mucosally transmissible SHIV challenge stocks containing HIV-1 CRF01_AE env derived from acutely HIV-1 infected individuals from Thailand. SHIV-AE6, SHIV-AE6RM, and SHIV-AE16 contained env sequences that were >99% identical to the original HIV-1 isolate and did not require in vivo passaging. These viruses exhibited CCR5 tropism and displayed a tier 2 neutralization phenotype. These challenge stocks efficiently infected rhesus monkeys by the intrarectal route, replicated to high levels during acute infection, and established chronic viremia in a subset of animals. SHIV-AE16 was titrated for use in single, high dose as well as repetitive, low dose intrarectal challenge studies. These SHIV challenge stocks should facilitate the preclinical evaluation of vaccines, monoclonal antibodies, and other interventions targeted at preventing HIV-1 CRF01_AE infection.     

Statistical Properties and Pre-Hit Dynamics of Price Limit Hits in the Chinese Stock Markets

Price limit trading rules are adopted in some stock markets (especially emerging markets) trying to cool off traders’ short-term trading mania on individual stocks and increase market efficiency. Under such a microstructure, stocks may hit their up-limits and down-limits from time to time. However, the behaviors of price limit hits are not well studied partially due to the fact that main stock markets such as the US markets and most European markets do not set price limits. Here, we perform detailed analyses of the high-frequency data of all A-share common stocks traded on the Shanghai Stock Exchange and the Shenzhen Stock Exchange from 2000 to 2011 to investigate the statistical properties of price limit hits and the dynamical evolution of several important financial variables before stock price hits its limits. We compare the properties of up-limit hits and down-limit hits. We also divide the whole period into three bullish periods and three bearish periods to unveil possible differences during bullish and bearish market states. To uncover the impacts of stock capitalization on price limit hits, we partition all stocks into six portfolios according to their capitalizations on different trading days. We find that the price limit trading rule has a cooling-off effect (object to the magnet effect), indicating that the rule takes effect in the Chinese stock markets. We find that price continuation is much more likely to occur than price reversal on the next trading day after a limit-hitting day, especially for down-limit hits, which has potential practical values for market practitioners.     

Further evidence of intraspecific heterochromatin variants in Drosophila melanogaster

The analysis of inter-strain heterochromatin polymorphism in mitotic chromosomes of Drosophila melanogaster was extended to some stocks characterized by chromosomal mutations. In particular, the present investigation aims to compare, in the same cell, the quinacrine banding of two different Y chromosomes of male hybrids derived from crosses using special stocks. A direct comparison of homologous heteromorphic chromosomes in F₁ hybrids provided additional evidence of differences in the fluorescence pattern of the Y chromosome, as well as in the length of the heterochromatin segment of the X chromosome.     

Can we see a cohort effect on survival of Steller sea lions (Eumetopias jubatus) at Kozlova Cape rookery (eastern Kamchatka,Russia)?

Steller sea lions ( Eumetopias jubatus ) have experienced a decline in Russia as well as the United States. The causes for the decline of the Russian population may or may not overlap the causes of the decline in Alaska. The demographics of the Russian population are not well understood and are an area of interest for scientists wishing to compare and contrast the Alaskan and Russian stocks. This study uses a unique observational system to assess survival by age at a small rookery on the Kamchatka Peninsula, Kozlova Cape. We proceeded under the hypothesis that changes in environmental conditions between years would produce noticeable differences in survival of pups born in those years. We found no evidence to support our hypothesis, but did find some differences from the Alaskan population in estimated survival for the juvenile stage class. This study also provides some of the history of Steller sea lions in Russia for context.     

Antigenic variants of herpes simplex virus selected with glycoprotein-specific monoclonal antibodies.

Monoclonal antibodies specific for herpes simplex virus type 1 (HSV-1) glycoproteins were used to demonstrate that HSV undergoes mutagen-induced and spontaneous antigenic variation. Hybridomas were produced by polyethylene glycol-mediated fusion of P3-X63-Ag8.653 myeloma cells with spleen cells from BALB/c mice infected with HSV-1 (strain KOS). Hybrid clones were screened for production of HSV-specific neutralizing antibody. The glycoprotein specificities of the antibodies were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of immunoprecipitates of radiolabeled infected-cell extracts. Seven hybridomas producing antibodies specific for gC, one for gB, and one for gD were characterized. All antibodies neutralized HSV-1 but not HSV-2. Two antibodies, one specific for gB and one specific for gC, were used to select viral variants resistant to neutralization by monoclonal antibody plus complement. Selections were made from untreated and bromodeoxyuridine- and nitrosoguanidine-mutagenized stocks of a plaque-purified isolate of strain KOS. After neutralization with monoclonal antibody plus complement, surviving virus was plaque purified by plating at limiting dilution and tested for resistance to neutralization with the selecting antibody. The frequency of neutralization-resistant antigenic variants selected with monoclonal antibody ranged from 4 X 10(-4) in nonmutagenized stocks to 1 X 10(-2) in mutagenized stocks. Four gC and four gB antigenic variants were isolated. Two variants resistant to neutralization by gC-specific antibodies failed to express gC, accounting for their resistant phenotype. The two other gC antigenic variants and the four gB variants expressed antigenically altered glycoproteins and were designated monoclonal-antibody-resistant, mar, mutants. The two mar C mutants were tested for resistance to neutralization with a panel of seven gC-specific monoclonal antibodies. The resulting patterns of resistance provided evidence for at least two antigenic sites on glycoprotein gC.     

Evidence of a genetic component in the seasonal return pattern of Atlantic salmon, Salmo salar L.

We tested the null hypothesis that differences in the seasonal return patterns between stocks of Atlantic salmon, Salmo salar L., are a result of a direct response to the environment, and not under genetic control. Two stocks were used in the experiments, originating from the R. Figga and R. Imsa, respectively. In their native habitat fish from the former are known to return to the home stream as adult salmon early in the summer, while from the latter return during late summer and autumn. By rearing these stocks in the same hatchery and releasing smolts of both stocks together at three sites in southern Norway, it was demonstrated that salmon from the R. Figga stock returned earlier to coastal Norway than salmon from the R. Imsa stock, as maturing adults. Thus, we reject the hypothesis that these stocks are genetically identical in this trait. Within both stocks, multi-sea-winter fish returned earlier than one-sea-winter fish. Within stocks, there was no significant difference in time of return between salmon released as 1- and 2-year-old smolts, or between fish reared from parents ascending the R. Imsa early or late in the season.     

渤、黄海蓝点马鲛种群鉴别的研究

本文讨论了渤海和黄海海域蓝点马鲛的种群问题,通过对各项性状特征差异的分析、计算以及生殖、分布回游习性的综合对比判别的结果表明:渤海与黄海诸海域群体均属同一种群。但黄海南部群体可视为同一种群的不同群体。     

Ecosystem carbon stocks of mangrove forests along the Pacific and Caribbean coasts of Honduras

Among the many ecosystem services provided by mangrove ecosystems, their role in carbon (C) sequestration and storage is quite high compared to other tropical forests. Mangrove forests occupy less than 1 % of tropical forested areas but account for approximately 3 % of global carbon sequestration by tropical forests. Yet there remain many areas where little data on the size and variation of mangrove C stocks exist. To address this gap and examine the range of C stocks in mangroves at landscape scales, we quantified C stocks of Honduran mangroves along the Pacific and Caribbean coasts and the Bay Islands. We also examined differences in ecosystem C stocks due to size and structure of mangrove vegetation found in Honduras. Ecosystem C stocks ranged from 570 Mg C ha^?1 in the Pacific coast to ~1000 Mg C ha^?1 in Caribbean coast and the Bay Islands. Ecosystem C stocks on the basis of mangrove structure were 1200, 800 and 900 Mg C ha^?1, in low, medium and tall mangroves, respectively. We did not find significant differences in ecosystem C stocks on the basis of location (Pacific coast, Caribbean coast and Bay Islands) or mangrove type (low, medium and tall). Mangrove soils represented the single largest pool of total C in these ecosystems, with 87, 81 and 94 % at the Pacific coast, Caribbean coast and the Bay Islands, respectively. While there were no significant differences in total ecosystem stocks among mangrove types, there were differences in where carbon is stored. Mangrove soils among low, medium and tall mangroves contained 99, 93 and 80 % of the total ecosystem C stocks. In addition, we found a small yet significant negative correlation between vegetation C pools and pore water salinity and pH at the sampled sites. Conversion of mangroves into other land use types such as aquaculture or agriculture could result in loses of these soil C reserves due to mineralization and oxidation. Coupled with their other ecosystem services, an understanding of the size of mangrove ecosystem C stocks underscores their values in the formulation of conservation and climate change mitigation strategies in Central America.     

Soil carbon stocks in stable tropical landforms are dominated by geochemical controls and not by land use

Soil organic carbon (SOC) dynamics depend on soil properties derived from the geoclimatic conditions under which soils develop and are in many cases modified by land conversion. However, SOC stabilization and the responses of SOC to land use change are not well constrained in deeply weathered tropical soils, which are dominated by less reactive minerals than those in temperate regions. Along a gradient of geochemically distinct soil parent materials, we investigated differences in SOC stocks and SOC (Δ¹⁴C) turnover time across soil profile depth between montane tropical forest and cropland situated on flat, non-erosive plateau landforms. We show that SOC stocks and soil Δ¹⁴C patterns do not differ significantly with land use, but that differences in SOC can be explained by the physicochemical properties of soils. More specifically, labile organo-mineral associations in combination with exchangeable base cations were identified as the dominating controls over soil C stocks and turnover. We argue that due to their long weathering history, the investigated tropical soils do not provide enough reactive minerals for the stabilization of C input in either high input (tropical forest) or low-input (cropland) systems. Since these soils exceeded their maximum potential for the mineral related stabilization of SOC, potential positive effects of reforestation on tropical SOC storage are most likely limited to minor differences in topsoil without major impacts on subsoil C stocks. Hence, in deeply weathered soils, increasing C inputs may lead to the accumulation of a larger readily available SOC pool, but does not contribute to long-term SOC stabilization.     

Anti-progesterone monoclonal antibody affects early cleavage and implantation in the mouse by mechanisms that are influenced by genotype

Pregnancy was blocked by anti-progesterone monoclonal antibody in two inbred (BALB/cJ, CBA/Ca) but to a lesser degree in an F1 hybrid (CBA/Ca male X BALB/cJ female) or an outbred (Tuck's no. 1) stock of mice when antibody was injected intraperitoneally (i.p.) at 32 h post coitum (p.c.) using a dosage of 9.5-10.9 nmol. This different antifertility effect could not be explained solely by altered tubal transport in inbred mice since the rate of transport was slightly accelerated in one stock (BALB/c) but not in another (CBA). In crossbred mice tubal transport was not significantly altered by antibody treatment. At Day 3 (54-58 h p.c.), the majority of embryos in control mice were at the 4-cell and 8-cell to morula stages in inbred and crossbred stock, respectively, but after antibody treatment they were mainly at the 4-cell stage in all 4 stocks. At Day 4 (78-82 h p.c.) the majority of embryos in control females had reached the blastocyst stage in all stocks, whereas after antibody treatment they had reached this stage in crossbred stock and relatively few had progressed so far in inbred stock. The results indicate that there are two events in early gestation which are susceptible to passive immunization with anti-progesterone monoclonal antibody. The first of these occurs during cleavage shortly after the 4-cell stage when embryo development was arrested in two inbred stocks of mice. Antibody effects on cleavage were not direct since embryos cultured in the presence of high concentrations of antibody, or antibody saturated with progesterone, continued to develop in the normal way and formed blastocysts. The second event is the onset of implantation, an effect also influenced by genotype. The decidual cell reaction induced by intraluminal oil injection was blocked by antibody injected at 8 or 32 h p.c. in BALB/c females, but only when injected at 8 h, and not at 32 h p.c., in F1 hybrid females. The results show that there is a greater resistance in two crossbred stocks compared with two inbred stocks to the effects of passive immunization against progesterone in early pregnancy.     

Estimation of nuclear DNA content by flow cytometry in fishes of the genus Xiphophorus

1. By use of flow cytometry we measured nuclear DNA content in cells from 16 stocks representing 9 species of the genus Xiphophorus. 2. Significant differences were detected between certain stocks and species with respect to DNA content. 3. Male-female differences were apparent in 5 of 7 stocks in which males and females were studied. 4. Estimation of nuclear DNA content is of potential significance in connection with the genetics of sex determination and the study of taxonomic relationships.