棉铃虫核型多角体病毒Ha105的序列分析及敲除和回复菌株的构建

通过生物信息学方法对Ha105的生物功能进行预测,运用λ噬菌体Red重组系统介导的同源重组,在大肠杆菌BW25113中,用含有350 bp同源臂的氯霉素抗性基因和绿色荧光蛋白基因替换了棉铃虫病毒细菌人工染色体HaBacHZ8上的Ha105基因,然后利用Bac-to-Bac系统把Ha105回复到Ha105缺失的重组病毒上,构建了Ha105的缺失和回复重组病毒.生物信息学分析结果表明,Ha105是bro基因家族成员,含有Bro-N结构域,可能对宿主细胞的转录和病毒复制有一定影响.此外,重组病毒的PCR及酶切结果表明,成功构建了vHaHa105-KO-PH-gfp缺失菌株和vHaHa105-REP-PH-gfp、vHaHa105-REP-gfp回复菌株.该Ha105缺失及回复菌株的获得为进一步研究Ha105的功能奠定基础.     

Macrofungi associated with vegetation and soils at Ha Ha Tonka State Park, Missouri

Fungi and vascular plant interactions are necessary components of natural community establishment, productivity and degradation. While many fungal species serve as decomposers of organic matter, others have evolved mutualistic or parasitic relationships with vascular plants. This research focused on characterizing associations among macrofungi, vascular plant communities and soils. Ha Ha Tonka State Park is in central Missouri and has a varying landscape with numerous natural community types that provide diverse habitats and microhabitats that are ideally suited to the investigation of fungal, floral and soil associations. Five communities sampled within the park included glades, open woodlands, flatwoods, closed-canopy forests and karst sinks. Permanent 0.01 ha. plots were surveyed in the 2006 and 2007 growing seasons. Surveys of plots and entire communities yielded 249 fungal taxa and approximately 265 floral taxa. Soils were analyzed to help define specific edaphic components of each community and used to associate soil attributes with plant and fungal communities. Forest communities contained the most ectomycorrhizal (ECM) fungi species. Karst sinks and glades had higher soil pH and phosphorus and fewer ectomycorrhizal fungi. Statistical analyses included non-metric multidimensional scaling, multiresponse permutation procedure and indicator species analysis. Indicator species were identified for flatwood, forest and karst communities, but results were inconclusive for glades and open woodlands.     

Digestive tract cell proliferation and food consumption patterns of Ha/ICR mice

The relationship between the daily pattern of food consumption and the proliferation rate of the oesophagus, stomach, forestomach, small intestine and colon of Ha/ICR mice was examined. Proliferative activity was determined by [3H]TdR incorporation on a wet weight tissue basis, along with selective counting of labelled nuclei. Under conditions of ad libitum feeding with a 12 hr light cycle (lights on at 0600) mice eat most of their food during the dark period. A distinct circadian rhythm was observed in the oesophagus, stomach, forestomach and colon with the peak of [3H]TdR incorporation between 0400 and 0600 and the nadir between 1600 and 1800. Although a circadian fluctuation was observed in the small intestine, its amplitude was much less than in other areas. This rhythmic change in proliferation rate could be phase shifted by allowing the mice to feed only between 0800 and 1600 for 14 days. Under these conditions the peak in proliferative activity occurred between 1800 and 2000. Fasting reduced the daily level of proliferative activity in all of the digestive tract sites studied, and for all areas except the oesophagus greatly reduced or eliminated the circadian fluctuation. The forestomach and colon were the most influenced by fasting with 24 hr [3H]TdR incorporation reduced to 30-40% of the control value. Refeeding following a 48 hr fast produced a rapid increase in proliferative activity peaking at levels well above the control value at 16 hr after the onset of refeeding. The major exception to this was the small intestine which slowly returned to the control value during the first 24 hr. Partial refeeding produced a diminished refeeding response. Once the normal pattern of food consumption was re-established following refeeding the normal proliferative fluctuations were again observed.     

Digestive Tract Cell Proliferation and Food Consumption Patterns of Ha/Icr Mice

The relationship between the daily pattern of food consumption and the proliferation rate of the qesophagus, stomach, forestomach, small intestine and colon of Ha/ICR mice was examined. Proliferative activity was determined by [³H]TdR incorporation on a wet weight tissue basis, along with selective counting of labelled nuclei. Under conditions of ad libitum feeding with a 12 hr light cycle (lights on at 0600) mice eat most of their food during the dark period. A distinct circadian rhythm was observed in the oesophagus, stomach, forestomach and colon with the peak of [³H]TdR incorporation between 0400 and 0600 and the nadir between 1600 and 1800. Although a circadian fluctuation was observed in the small intestine, its amplitude was much less than in other areas. This rhythmic change in proliferation rate could be phase shifted by allowing the mice to feed only between 0800 and 1600 for 14 days. Under these conditions the peak in proliferative activity occurred between 1800 and 2000. Fasting reduced the daily level of proliferative activity in all of the digestive tract sites studied, and for all areas except the oesophagus greatly reduced or eliminated the circadian fluctuation. the forestomach and colon were the most influenced by fasting with 24 hr [³H]TdR incorporation reduced to 30–40% of the control value. Refeeding following a 48 hr fast produced a rapid increase in proliferative activity peaking at levels well above the control value at 16 hr after the onset of refeeding. the major exception to this was the small intestine which slowly returned to the control value during the first 24 hr. Partial refeeding produced a diminished refeeding response. Once the normal pattern of food consumption was re-established following refeeding the normal proliferative fluctuations were again observed.     

Improvement of human skin cell growth by radiation-induced modifications of a Ge/Ch/Ha scaffold

Gelatin-/chitosan-/hyaluronan-based biomaterials are used in tissue engineering as cell scaffolds. Three gamma radiation doses (1, 10 and 25 kGy) were applied to scaffolds for sterilization. Microstructural changes of the irradiated polymers were evaluated by using scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). A dose of 25 kGy produced a rough microstructure with a reduction of the porosity (from 99 to 96 %) and pore size (from 160 to 123 μm). Radiation also modified the glass transition temperature between 31.2 and 42.1 °C (1 and 25 kGy respectively). Human skin cells cultivated on scaffolds irradiated with 10 and 25 kGy proliferated at 48 h and secreted transforming growth factor β3 (TGF-β3). Doses of 0 kGy (non-irradiated) or 1 kGy did not stimulate TGF-β3 secretion or cell proliferation. The specific growth rate and lactate production increased proportionally to radiation dose. The use of an appropriate radiation dose improves the cell scaffold properties of biomaterials.     

DBA/2J and DBA/2Ha lymphocytes differ in their ability to induce graft-vs-host disease

Graft-vs-host disease (GVHD) is a common occurrence after bone marrow transplantation despite the use of MHC-matched donors and recipients. This indicates that non-MHC loci play an important role in the regulation and development of GVHD. Non-MHC loci have been shown to regulate GVHD in a murine model where acute GVHD results from i.v. injection of C57BL/6J spleen cells into B6D2F1/J [C57BL/6J X DBA/2J)F1) recipients while chronic GVHD results from injection of DBA/2J spleen cells. In contrast to the hyperproduction of Ig and auto-antibodies that is characteristic of the chronic GVHD that occurs after injection of DBA/2J cells, injection of DBA/2Ha cells was found to induce CTL and suppressor cells characteristic of the acute GVHD that results from injection of C57BL/6 cells into B6D2F1/J recipients. Genetic analysis indicated that one autosomal locus is responsible for the different GVHD responses of DBA/2J and DBA/2Ha cells and that the DBA/2Ha allele is dominant. Further studies indicate that the different responses by DBA/2J and DBA/2Ha cells is not due to functional differences between the two sets of cells but by a radiosensitive B6D2F1 recipient immune response which discriminates between the DBA/2J and DBA/2Ha spleen cells.     

After the Massacre: Commemoration and Consolation in Ha My and My Lai

After the Massacre: Commemoration and Consolation in Ha My and My Lai . Heonik Kwon. Berkeley: University of California Press, 2006. 217 pp.     

RFLP mapping of the Ha 2 cereal cyst nematode resistance gene in barley

 The cereal cyst nematode (CCN), Heterodera avenae Woll., is an economically damaging pest of barley in many of the world’s cereal-growing areas. The development of CCN-resistant cultivars may be accelerated through the use of molecular markers. A number of resistance genes against the pest are well known; one of them, the single dominant Ha 2 resistance gene, has been shown to be effective against the Australian pathotype and maps to chromosome 2 of barley. Segregation analysis identified two restriction fragment length polymorphism (RFLP) markers flanking the resistance gene in two doubled-haploid populations of barley. AWBMA 21 and MWG 694 mapped 4.1 and 6.1 cM respectively from the Ha 2 locus in the Chebec×Harrington cross and 4.0 and 9.2 cM respectively in the Clipper×Sahara cross. Analysis of a further seven sources of CCN resistance in the form of near-isogenic lines (NILs) indicates that all available sources of resistance to the Australian pathotype of CCN in barley represent the Ha 2 locus. Received: 5 December 1996 / Accepted: 20 December 1996     

Lower Emsian biostratigraphy and event stratigraphy of Ha Giang Province,northern Vietnam

A new species of rugose coral, Sanidophyllum dubium n. sp., and the typical Emsian (Early Devonian) rugose coral Xystriphylloides nobilis are described from the Mia Le Formation in northern Vietnam. The lower Emsian index conodonts ranging from the Polygnathus excavatus zone to the P. nothoperbonus zone are illustrated. The biostratigraphic correlation between northern Vietnam and South China shows that the Mia Le Formation in northern Vietnam is early Emsian in age, and its upper part can be correlated with the lower part of the Shizhou Member of the Yukiang Formation in Liujing, Guangxi and its equivalents in South China. Based on the study of the lower Emsian biostratigraphic sequence, the disappearance of Xystriphylloides nobilis fauna in the overlying bed of the uppermost Mia Le Formation and the extinction of the “tonkinensis fauna” (sensu lato) in the interval between the basal Si Phai Formation and the uppermost Mia Le Formation demonstrate the influence of the Yujiang Event in northern Vietnam.     

The Swiss/ICR (Ha) albino mouse as an experimental host for infectious pancreatic necrosis virus of trout

Intracranial inoculation of infectious pancreatic necrosis virus (IPNV), a pathogen of several species of trout, produced pancreatic necrosis in suckling Swiss albino mice. Peri-nuclear halos, cytoplasmic vacuoles, and necrosis were found in histologic sections of pancreas taken from mice killed 21 days post-inoculation. Virus was recovered from the pancreas of mice killed as early as 10 days post-inoculation. Rivers' postulates were fulfilled. Virus recovered from the infected mouse pancreas was neutralized by IPNV specific antiserum. The significance of the mouse as an experimental host is discussed.     

Pyruvate formate lyase inRhodospirillum rubrum Ha adapted to anaerobic dark conditions

The fermatation metabolism ofRhodospirillum rubrum Ha was studied after adaptation of both light-anaerobic and dark aerobic to dark anaerobic conditions.Pyruvate was metabolized to acetate, formate, CO₂ and propionate by suspensions of cells adapted to anaerobiosis. Pyruvate cleavage to formate accounted for about two-thirds of the pyruvate decomposed. This process was catalyzed by a coenzyme A dependent pyruvate formate lyase. In carboxylate- and nucleotide-free extracts, the substrate concentrations for half-maximal velocity [S]_0.5V were found to be 1.5 mM for pyruvate and 75 M for coenzyme A.Pyruvate formate lyase could practically not be demonstrated in light-anaerobic photosynthesizing cells. Lyase activity was low at a basic level in darkaerobic respiring cells. After adaptation of both types of cells under growth conditions to dark anaerobiosis lyase activity increased about 10-fold. Highest levels could be observed in cells grown aerobically in the dark on pyruvate after transition to dark anaerobic conditions. It is concluded that pyruvate formate lyase is the characteristic key enzyme of the dark-anaerobic fermentative metabolism ofR. rubrum Ha.     

Normal cellular Ha ras p21 protein causes local disruption of bilayer phospholipid

We have investigated the interactions of the p21 protein of c-Ha ras with its phospholipid environment. Gel filtration of detergent-"solubilized" p21 revealed that this preparation consisted of a mixture of multimolecular aggregates of protein and phospholipid and also a population of individual p21 molecules. Addition of 8 M urea to p21 preparations increased the solubility of the molecule in detergent solutions upon the removal of this denaturant. The progressive addition of the detergent cholate appeared to increase the efficiency of p21 preparations to bind GTP. This affinity for GTP was not removed even at high detergent concentrations, when delipification of the p21 was presumably effected. Modification of the composition of the phospholipid species surrounding the protein did not appear to alter its affinity for GTP. Electron spin resonance studies with membrane spin-labels indicated a perturbation of the bilayer extending to between 44 and 100 phospholipids surrounding the molecule. However, no evidence was found for any population of intimately bound phospholipid, which is seen as an annulus of about 30 lipids in transmembrane proteins such as Ca2+-ATPase. From these results we propose that the Ha ras p21 protein has the ability to associate directly with the membrane in a manner clearly discernible from that of a transmembrane protein.