DNA divergence in and around the alcohol dehydrogenase locus in five closely related species of Hawaiian Drosophila

The alcohol dehydrogenase (Adh) region from five planitibia subgroup species of Hawaiian picture-wing Drosophila has been cloned. A total of 15 kb of DNA in and around the Adh gene has been compared among the five species. Genetic distances were calculated to determine evolutionary relationships. These distances agree with previous distances determined by protein polymorphism and DNA hybridization techniques and can be interpreted in terms of specific island colonization and speciation (founder) events over the past 5 Myr. Examination of the restriction maps of the cloned Adh region from the five species shows many instances of small deletions, insertion of a transposable element in D. heteroneura, and the existence of a highly variable region on the 3' side of the Adh gene. Clustering relationships and rates of DNA change are calculated and compared with the relationship found for other species of Drosophila.      

Identification of novel QTLs for seedling and adult plant leaf rust resistance in a wheat doubled haploid population

Pyramiding of genes that confer partial resistance is a method for developing wheat (Triticum aestivum L.) cultivars with durable resistance to leaf rust caused by Puccinia triticina. In this research, a doubled haploid population derived from the cross between the synthetic hexaploid wheat (SHW) (×Aegilotriticum spp.) line TA4152-60 and the North Dakota breeding line ND495 was used for identifying genes conferring partial resistance to leaf rust in both the adult plant and seedling stages. Five QTLs located on chromosome arms 3AL, 3BL, 4DL, 5BL and 6BL were associated with adult plant resistance with the latter four representing novel leaf rust resistance QTLs. Resistance effects of the 4DL QTL were contributed by ND495 and the effects of the other QTLs were contributed by the SHW line. The QTL on chromosome arm 3AL had large effects and also conferred seedling resistance to leaf rust races MJBJ, TDBG and MFPS. The other major QTL, which was on chromosome arm 3BL, conferred seedling resistance to race MFPS and was involved in a significant interaction with a locus on chromosome arm 5DS. The QTLs and the associated molecular markers identified in this research can be used to develop wheat cultivars with potentially durable leaf rust resistance.     

Germ band retraction as a landmark in glucose metabolism during <Emphasis Type="Italic">Aedes aegypti</Emphasis> embryogenesis

Background  

The mosquito A. aegypti is vector of dengue and other viruses. New methods of vector control are needed and can be achieved by a better understanding of the life cycle of this insect. Embryogenesis is a part of A. aegypty life cycle that is poorly understood. In insects in general and in mosquitoes in particular energetic metabolism is well studied during oogenesis, when the oocyte exhibits fast growth, accumulating carbohydrates, lipids and proteins that will meet the regulatory and metabolic needs of the developing embryo. On the other hand, events related with energetic metabolism during A. aegypti embryogenesis are unknown.     

大鼠心肌缺血再灌注损伤模型的实验研究

目的 制备一种新型的心肌急性缺血再灌注损伤模型,以探讨一种更符合临床实际需求的实验方法.方法 将20只雌性SD(Sprague-Dawley)大鼠随机分成2组(对照组、实验组),采用结扎主动脉根部引起心肌缺血5min再灌注30 min建立心肌急性缺血再灌注模型;通过应用透射电镜观察心肌细胞超微结构的改变,同时检测心肌组织匀浆丙二醛(Maleic Dialdehyde,MDA)含量、超氧化物歧化酶(Superoxide Dismutase,SOD)活力.结果 透射电镜下超微结构显示实验组较对照组明显加重了心肌组织结构和线粒体的损害;实验组心肌组织MDA明显高于对照组(P<0.01),而SOD明显低于对照组(P<0.01).结论 本实验成功建立了方法简便、易于操作、取材范围广泛的心肌缺血再灌注损伤模型,为心肌缺血再灌注损伤研究提供了一种更为可行的模型.     

Beneficial effect of fluorocarbon emulsion media on the function of neuromuscular preparations in vitro

The effects of liquid fluorocarbons as bathing media were determined by use of in vitro neuromuscular preparations. Rat hemidiaphragms were bathed in either oxygenated fluorocarbon (FC) emulsion or standard oxygenated Krebs solution. Contractile force in response to simple supramaximal nerve stimuli as well as to high frequency stimulation was greater, while twitch:tetanus ratio was smaller in FC emulsion. With such medium, post-tetanic potentiation of contraction was also more consistently observed. Indirectly stimulated diaphragms survived longer in FC emulsion. After cessation of oxygenation, oxygen tension (ρO(2)) of the medium declined more rapidly with Krebs than with FC emulsion; ρO(2) directly correlated with force of contraction. Similarly, in the chick biventer cervicis preparation, FC emulsion enhanced nerve-stimulated force of contraction; returning the preparation to standard Krebs solution reversed this phenomenon. Dose-resonse curves of muscle contraction in response to acetycholine and KCl administration were shifted upward during FC emulsion superfusion. Frequency of miniature endplate potentials was lower in FC emulsion than that observed in Krebs solution, measured from the same cell of the rat diaphragm. Resting membrane potentials were also greater in muscle cells sampled from FC emulsion-bathed preparations. These data suggest that FC emulsion is superior to standard Krebs solution as a bathing medium for in vitro neuromuscular preparations by virtue of the high solubility of oxygen in it.     

Rank orders and division of labour among unrelated cofounding ant queens

Young, unrelated queens may cooperate in colony founding (pleometrosis) in many species of ants. Whereas the founding queens of many 'advanced' species rely completely on body reserves in order to rear their first young, queens of the ponerine Pachycondyla 'inversa' forage for food. In founding associations, only one queen specializes in this risky task. Here we show that the division of labour is strongly affected by aggressive interactions between cofounding queens: the dominant remains in the nest and guards the brood, whereas the subordinate is forced to leave and forage. The frequency of queen antagonism increased with the duration since food was last added to the foraging arena. Egg-laying rates did not differ significantly between nest-mate queens, but dominant queens destroyed and ate some of the eggs laid by subordinates.     

Tracking wheat rust on a continental scale

The rusts of wheat are important fungal plant pathogens that can be disseminated thousands of kilometers across continents and oceans by wind. Rusts are obligate parasites that interact with resistance genes in wheat in a gene-for-gene manner. New races of rust develop by mutation and selection for virulence against rust resistance genes in wheat. In recent years, new races of wheat leaf rust, wheat stripe rust, and wheat stem rust have been introduced into wheat production areas in different continents. These introductions have complicated efforts to develop wheat cultivars with durable rust resistance and have reduced the number of effective rust-resistance genes that are available for use. The migration patterns of wheat rusts are characterized by identifying their virulence against important rust resistance genes in wheat and by the use of molecular markers.