Nutrient absorption and utilization by wing and flight muscle morphs of the cricket Gryllus firmus: implications for the trade-off between flight capability and early reproduction

Absorption efficiency (AD, approximate digestibility, assimilation efficiency) of various macronutrients and conversion of absorbed nutrients to biomass (ECD) were compared among the two types of flightless morph and the flight-capable morph of the cricket, Gryllus firmus. No biologically significant phenotypic or genetic difference in AD for carbohydrate, protein or lipid was observed among morphs fed either a high-nutrient (100%) or a low-nutrient (25%) diet. Thus, previously-documented differences among adult morphs in carbohydrate and lipid content must be caused by processes other than variation in nutrient absorption by morphs during adulthood. Relative absorption efficiency of total dry mass of food by morphs of G. firmus appears to be a valid indicator of relative AD of total calories. Morphs did not differ phenotypically or genetically in the excretion of end products of nitrogen metabolism (uric acid, hypoxanthine plus xanthine) on either the high nutrient or the low nutrient diet. Nutritional indices corrected for excreted nitrogenous metabolites were very similar to uncorrected indices, and the pattern of variation among the morphs was the same for corrected or uncorrected values. Each of the two types of flightless morph converted a greater proportion of absorbed nutrients into body mass, mainly ovaries, and allocated a smaller proportion of assimilated nutrients to respiration than did the flight-capable morph. Moreover, the trade-off between respiration and early reproduction was substantially magnified on the low nutrient diet. These results extend previous findings of a trade-off between flight capability and early reproduction in wing-polymorphic Gryllus species (1) to diets of very different nutrient quantity, and (2) to flightlessness arising from different causes: blockage of flight muscle development in juveniles vs histolysis of fully-developed flight muscles in adults.     

Developing efficient strategies for the generation of transgenic cattle which produce biopharmaceuticals in milk

At the close of the millennium, a revolution in the treatment of disease is taking shape due to the emergence of new therapies based on human recombinant proteins. The ever-growing demand for such pharmaceutical proteins is an important driving force for the development of safe and large-scale production platforms. Since the efficacy of a human protein is generally dependent on both its amino acid composition as well as various post-translational modifications, many recombinant human proteins can only be obtained in a biologically active conformation when produced in mammalian cells. Hence, mammalian cell culture systems are often used for expression. However, this approach is generally known for limited production capacity and high costs. In contrast, the production of (human) recombinant proteins in milk of transgenic farm animals, particularly cattle, presents a safe alternative without the constraint of limited protein output. Moreover, compared to cell culture, production in milk is very cost-effective. Although transgenic farm animal technology was still in its infancy a decade ago, today it is on the verge of fulfilling its potential of providing therapeutic proteins that can not be produced otherwise in sufficient quantities or at affordable cost. Since 1989, we have been at the forefront of this development, as illustrated by the birth of Herman, the first transgenic bull. In this communication, we will present an overview of approaches we have taken over the years to generate transgenic founder animals and production herds. Our initial strategies were based on microinjection; at the time the only viable option to generate transgenic cattle. Recently, we have adopted a more powerful approach founded on the application of nuclear transfer. As we will illustrate, this strategy presents a breakthrough in the overall efficiency of generating transgenic animals, product consistency, and time of product development.     

冬小麦原生质体培养的胚状体直接发生

冬小麦品种“京花一号”胚性愈伤组织在改良的N₆培养基(NBD培养基)上继代得到易碎型胚性愈伤组织,转入改良MS液体培养基(MSDL培养基)后得到胚性悬浮系,分离的原生质体在改良的MS培养基(MSDP培养基)上培养,再生细胞直接产生体细胞胚胎,并再生出完整植株。体细胞胚胎形成过程与小麦合子胚的形成过程十分相似。     

The influence of surface charges on the conductance of the human connexin37 gap junction channel

The single-channel conductance of the hCx37 homotypic gap junction channel does not saturate with transjunctional voltages up to +/-75 mV, nor does it depend linearly on the intracellular electrolyte concentration. The average maximum unitary conductances measured in KCl were 175 pS (30 mM), 236 pS (55 mM), 343 pS (110 mM), and 588 pS (270 mM) in the presence of 0.1 mM MgCl(2). The unexpectedly high unitary conductance at low salt concentrations can be explained by fixed charge groups within or near the channel orifice. Fixed cytoplasmic surface charges (3.4 e) positioned adjacent (15 A) to the channel pore adequately model the data (surface charge density of 0.24 e/(nm)(2)). In other experiments, high Mg(2+) reduced the unitary conductance of hCx37 homotypic gap junction channels more than predicted by screening alone, consistent with specific effects of Mg(2+) on the channel.     

白介素-6细胞因子家族新成员：心肌营养素-1

心肌营养素-1(cardiotrophin-1, CT-1)是一个新发现的白介素-6家族细胞因子,小鼠CT-1的mRNA长约1.4 kb,编码蛋白由203个氨基酸组成,以gp130和LIFR为受体.CT-1对心肌细胞既有肥大诱导作用,又有保护作用;能改变交感神经元的递质表型,促进多巴胺神经元、睫状神经元和运动神经元的存活;还能抑制骨髓白血病细胞M1的生长;诱导肝细胞急性相反应;小鼠腹腔注射给药可增加血小板、红细胞记数和血红蛋白浓度.     

An Arabidopsis embryonic lethal mutant with reduced expression of alanyl—t RNA synthetase gene

In present paper,one of the T-DNA insertional embryonic lethal mutant of Arabidopsis is identified and designated as acd mutant.The embryo developmant of this mutant is arrested in globular stage,The cell division pattern is abnormal during early embryogenesis and results in distubed cellular differentiation.Most of mutant embryos are finally degenerated and aborted in globular stage,However,a few of them still can germinate in agar palte and produce seedlings with shoter hypoctyl and distorted shoot meristem.To understand the molecular basis of the phenotype of this mutant,the joint fragment of T-DNA/plant DNA is isolated by plasmid rescue and Dig-labeled as probe for cDNA library screening.According to the sequence analysis and similarity searching,a 936 bp cDNA sequence(EMBL accession #:Y12555)from selectoed positive clone shows a 99.8%(923/925bp) sequence homolgy with Alanyl-tRNA Synthetase(AlaRS) gene of Arabidopsis thaliana.Furthermore,the data of in situ hybridization experiment indicate that the expression of Ala RS gene is weak in early embryogenesis and declines along with globular embryodevelopment in this mutant Accordingly,the reduced expression of Ala RS gene may be closely related to the morphological changes in early embryogenesis of this lethal mutant.     

Ecotoxicological threshold levels of a mixture of herbicides (atrazine, diuron and metolachlor) in freshwater microcosms

Twelve indoor, plankton-dominated, freshwater microcosms (600 l) were used to study the effect of a mixture of herbicides on structural and functional aspects of these ecosystems. The EC50, 72 h values of the most susceptible standard test alga Selenastrum capricornutum (EC50, atrazine=54 μg l−1, EC50, diuron=15 μg l−1, EC50, metolachlor=56 μg l−1) were used as a starting point for the dosage applied in the microcosms (dosages: 0, 0.01, 0.03, 0.1, 0.3, 1× EC50). The microcosms were exposed to chronic levels for 28 days and subsequently monitored for 4 more weeks. The following effects were observed: (1) direct effects became apparent from an initial drop in photosynthesis efficiency, pH and oxygen concentration and a decrease in the abundance of several phytoplankton taxa at the 0.3 × EC50 treatment level and higher. (2) Fourteen days post application an increase in the abundance of several phytoplankton taxa (Chlamydomonas sp. and Stephanodiscus/Cyclotella) was observed; oxygen concentrations recovered while alkalinity, conductivity and total inorganic nitrogen were elevated. (3) Effects on fauna were minor. Daphnia galeata showed a decreasing trend and the cyclopoid copepods an increasing trend at the end of the experiment. Multivariate statistical analyses demonstrated no effects of any treatment level on the zooplankton community. Effects were reported for the phytoplankton community at dose levels of 0.3 × EC50 and higher. On species level the most sensitive taxon was Chlorophyceae coccales. For this taxon a NOEC at the dose level of 0.01 × EC50 was calculated. This effect however was relatively small in magnitude and merely based on an increase in numbers in the control and lowest treated microcosms rather than a decrease in numbers in all other treatments. The standards based on algal toxicity data, as adopted by the Uniform Principles, consist of a safety factors of 0.1 to be multiplied with the EC50. The NOEC of coccales was lower than 0.1 × EC50. All other observed variables in this aquatic ecosystem were sufficiently protected against the mixture of herbicides by the safety factor as proposed in the Uniform Principles. This revised version was published online in August 2006 with corrections to the Cover Date.     

Environmental change and the phenology of European aphids

Aphids, because of their short generation time and low developmental threshold temperatures, are an insect group expected to respond particularly strongly to environmental changes. Forty years of standardized, daily data on the abundance of flying aphids have been brought together from countries throughout Europe, through the EU Thematic Network 'EXAMINE'. Relationships between phenology, represented by date of first appearance in a year in a suction trap, of 29 aphid species and environmental data have been quantified using the residual maximum likelihood (REML) methodology. These relationships have been used with climate change scenario data to suggest plausible changes in aphid phenology. In general, the date of first record of aphid species in suction traps is expected to advance, the rate of advance varying with location and species, but averaging 8 days over the next 50 years. Strong relationships between aphid phenology and environmental variables have been found for many species, but they are notably weaker in species living all year on trees. Canonical variate analysis and principal coordinate analysis were used to determine ordinations of the 29 species on the basis of the presence/absence of explanatory variables in the REML models. There was strong discrimination between species with different life cycle strategies and between species feeding on herbs and trees, suggesting the possible value of trait-based groupings in predicting responses to environmental changes.