模拟及实地条纹黄瓜甲虫脱叶作用对‘Carolina’黄瓜光合反应的影响(英文)

１９９５年作者进行了田间试验来比较模拟的条纹黄瓜甲虫 Ａｃａｌｙｍｍａ　Ｖｉｔｔａｔｕｍ（Ｆ）脱叶作用及实地Ａ．ｖｉｔｔａｔｕｍ脱叶作用对‘Ｃａｒｏｌｉｎａ’黄瓜光合反应的影响。在５个生长阶段（从第一片真叶到收获）中,共模拟了６种脱叶水平（０％一１００％）。在每一生长阶段,每点植株每周两次用剪子去叶,这一处理叫连续脱叶。除此之外,对同一生长阶段植株也用了一次性脱叶处理,但只有４种脱叶水平（０,２５,５０及１００％）。用Ａ．ｖｉｔｔａｔｕｍ成虫笼养试验来估计实地害虫脱叶危害。每笼中甲虫放置时间为两周,密度各为每株０,１,３,５及１０头,测定其净光合速率。在模拟及实地害虫脱叶处理之间,没有测到显著的光合速率差异（ Ｐ＞０． ０５）。在模拟害虫脱叶试验中,受损叶片和未受损叶片的光合速率也很少有显著差异。结果显示模拟害虫脱叶处理过程不仅能准确反映实地Ａ．ｖｉｔｔａｔｕｍ脱叶危害下的‘Ｃａｒｏｌｉｎａ’黄瓜的生长反应,而且也适用于确定Ａ．ｖｉｔｔａｔｕｍ对黄瓜的经济危害水平。     

Rampant horizontal transfer and duplication of rubisco genes in eubacteria and plastids

Previous work has shown that molecular phylogenies of plastids, cyanobacteria, and proteobacteria based on the rubisco (ribulose-1,5- bisphosphate carboxylase/oxygenase) genes rbcL and rbcS are incongruent with molecular phylogenies based on other genes and are also incompatible with structural and biochemical information. Although it has been much speculated that this is the consequence of a single horizontal gene transfer (of a proteobacterial or mitochondrial rubisco operon into plastids of rhodophytic and chromophytic algae), neither this hypothesis nor the alternative hypothesis of ancient gene duplication have been examined in detail. We have conducted phylogenetic analyses of all available bacterial rbcL sequences, and representative plastid sequences, in order to explore these alternative hypothesis and fully examine the complexity of rubisco gene evolution. The rbcL phylogeny reveals a surprising number of gene relationships that are fundamentally incongruent with organismal relationships as inferred from multiple lines of other molecular evidence. On the order of six horizontal gene transfers are implied by the form I (L8S8) rbcL phylogeny, two between cyanobacteria and proteobacteria, one between proteobacteria and plastids, and three within proteobacteria. Alternatively, a single ancient duplication of the form I rubisco operon, followed by repeated and pervasive differential loss of one operon or the other, would account for much of this incongruity. In all probability, the rubisco operon has undergone multiple events of both horizontal gene transfer and gene duplication in different lineages.      

Developmental expression of adenosine deaminase in placental tissues of the early postimplantation mouse embryo and uterine stroma

In this study, we have investigated the distribution of adenosine deaminase (ADA) in embryonic, extra-embryonic, and decidual tissues of the developing mouse embryo. ADA catalyzes a key step in purine metabolism converting adenosine to inosine. ADA specific activity (nmol/min/micrograms protein) was present at low levels in the embryo-decidual unit during the first 2 days of postimplantation development but then increased starting late on Day 6 of gestation (Day 0 plug). By Day 9, ADA specific activity was 80-fold higher than on Day 6. A histochemical staining method for ADA activity was applied to cryostat sections of the implantation site. The developmental increase localized primarily to the trophoblast/antimesometrial decidua interface between Days 7 and 9 of gestation, and decidua basalis and the metrial gland by Day 11. Immunofluorescent staining with sheep anti-mouse ADA antiserum confirmed the presence of ADA antigenicity in tissues forming the maternal/fetal interface. ADA specific activity was 19-fold higher in homogenates of the Day 11 decidua/parietal yolk sac than in the thymus, a tissue generally thought of as ADA-rich. High levels of ADA activity and immunoreactivity were also detected in the embryonal plasma during organogenesis, but the embryo proper showed only low levels. These results indicate that ADA is tightly regulated within tissues forming the maternal/fetal interface during early postimplantation stages of development.     

Cytotoxic activity ofEscherichia coli O157:H7 culture filtrate on the mouse colon and kidney

Escherichia coli O157:H7 culture filtrate (O157CF) produced colonic and renal lesions in mice following intraperitoneal or intravenous injection. Colonic lesions were characterized by death and sloughing of both surface and crypt epithelial cells, leading to loss of the mucous membrane and subsequent occult colonic hemorrhage. Several areas of severe colonic damage existed where loss of the epithelium and lamina propria was complete, leaving only the submucosal and smooth muscle layers intact. The colon was the only portion of the gastrointestinal tract affected by O157CF. Renal lesions were characterized by marked vacuolation and general necrosis of proximal convoluted tubular cells, and the presence of numerous exfoliated renal epithelial cells in the lumina of distal convoluted and collecting tubules. A neurogenic response was demonstrated by paralysis of the animals' rear extremities. The mouse was a useful model for detecting and studying in vivo the toxic properties of O157CF.     

Cholinergic interneurons mediate fast VGluT3-dependent glutamatergic transmission in the striatum

The neurotransmitter glutamate is released by excitatory projection neurons throughout the brain. However, non-glutamatergic cells, including cholinergic and monoaminergic neurons, express markers that suggest that they are also capable of vesicular glutamate release. Striatal cholinergic interneurons (CINs) express the Type-3 vesicular glutamate transporter (VGluT3), although whether they form functional glutamatergic synapses is unclear. To examine this possibility, we utilized mice expressing Cre-recombinase under control of the endogenous choline acetyltransferase locus and conditionally expressed light-activated Channelrhodopsin2 in CINs. Optical stimulation evoked action potentials in CINs and produced postsynaptic responses in medium spiny neurons that were blocked by glutamate receptor antagonists. CIN-mediated glutamatergic responses exhibited a large contribution of NMDA-type glutamate receptors, distinguishing them from corticostriatal inputs. CIN-mediated glutamatergic responses were insensitive to antagonists of acetylcholine receptors and were not seen in mice lacking VGluT3. Our results indicate that CINs are capable of mediating fast glutamatergic transmission, suggesting a new role for these cells in regulating striatal activity.     

A computerized apparatus designed to automatically dispense, measure, and record alcohol consumption by individual members of a rhesus macaque social group: trait-like drinking across social- and single-cage conditions

BACKGROUND: The present study tested the validity of an automated ethanol dispensing apparatus that is capable of identifying individual monkeys and precisely measuring their levels of ethanol consumption while living in a social group, and assessed individual subjects' level of consumption when alone and in social groups. METHODS: In Experiment 1, 21 rhesus macaques (Macaca mulatta) were given access for 1-h each day to the dispensing apparatus, which contained an aspartame-sweetened 8.4% (v/v) ethanol solution. Measurements of blood ethanol concentrations were taken for each subject and compared with the level of consumption recorded by the apparatus for those subjects. To examine the possibility that competition among the animals limited their access to the dispensing unit, in Experiment 2, 10 of the subjects used in Experiment 1 were singly housed to allow them to drink without interference from other monkeys. A correlation was then performed to assess the interindividual relationship between the amount of ethanol consumed in these two housing conditions. RESULTS: In Experiment 1, the volume of solution measured and recorded by the apparatus correlated positively with the true volume dispensed. Furthermore, the volume of solution reported by the computer to have been consumed by an individual subject correlated positively with blood ethanol concentrations. In Experiment 2, the volume of ethanol consumed by individual subjects in single cages correlated positively with their consumption in the social group. CONCLUSIONS: The apparatus accurately identified and measured individual patterns of ethanol consumption among socially housed animals. Additionally, individual differences in ethanol consumption remained stable across settings, as shown by the strong positive correlation between drinking in a social setting versus drinking alone. This finding may thus reflect an individual's constitutional proclivity to consume alcohol.     

Imported longhorned weevil (Coleoptera: Curculionidae) injury to soybean: physiological response and injury guild-level economic injury levels

The imported longhorned weevil, Calomycterus setarius Roelofs, is an occasional pest of soybean, Glycine max (L.), and can cause substantial defoliation of seedling soybean when the weevil is present in large numbers. Because weevil populations can reach high levels, the potential exists for significant seedling injury, so economic injury levels (EILs) are needed for imported longhorned weevil on seedling soybean. Because the bean leaf beetle, Cerotoma trifurcata (Forster), also is present on seedling soybean, injury by this insect should be included in EIL calculations. This study was conducted to (1) determine daily soybean consumption rates of imported longhorned weevil; (2) compare soybean injury responses between weevil injured and noninjured soybeans; and (3) develop multiple species EILs for imported longhorned weevil and bean leaf beetle. Field and laboratory studies were conducted in 1997 to determine weevil daily consumption rates. Field experiments were conducted in 1998 to examine physiological responses of soybean to weevil injury. Field and laboratory consumption rates were 0.16 and 0.21 cm2 per day, respectively. There were no significant differences in physiological responses (i.e., photosynthetic rates, stomatal conductance, and transpiration rates) between noninjured soybean leaflets (caged) and weevil-injured leaflets. Multiple-species EILs were developed for imported longhorned weevil and bean leaf beetle on VC through V3 soybean.     

Impact of ivermectin on onchocerciasis transmission: assessing the empirical evidence that repeated ivermectin mass treatments may lead to elimination/eradication in West-Africa

BACKGROUND: The Onchocerciasis Control Program (OCP) in West Africa has been closed down at the end of 2002. All subsequent control will be transferred to the participating countries and will almost entirely be based on periodic mass treatment with ivermectin. This makes the question whether elimination of infection or eradication of onchocerciasis can be achieved using this strategy of critical importance. This study was undertaken to explore this issue. METHODS: An empirical approach was adopted in which a comprehensive analysis was undertaken of available data on the impact of more than a decade of ivermectin treatment on onchocerciasis infection and transmission. Relevant entomological and epidemiological data from 14 river basins in the OCP and one basin in Cameroon were reviewed. Areas were distinguished by frequency of treatment (6-monthly or annually), endemicity level and additional control measures such as vector control. Assessment of results were in terms of epidemiological and entomological parameters, and as a measure of inputs, therapeutic and geographical coverage rates were used. RESULTS: In all of the river basins studied, ivermectin treatment sharply reduced prevalence and intensity of infection. Significant transmission, however, is still ongoing in some basins after 10-12 years of ivermectin treatment. In other basins, transmission may have been interrupted, but this needs to be confirmed by in-depth evaluations. In one mesoendemic basin, where 20 rounds of four-monthly treatment reduced prevalence of infection to levels as low as 2-3%, there was significant recrudescence of infection within a few years after interruption of treatment. CONCLUSIONS: Ivermectin treatment has been very successful in eliminating onchocerciasis as a public health problem. However, the results presented in this paper make it almost certain that repeated ivermectin mass treatment will not lead to the elimination of transmission of onchocerciasis from West Africa. Data on 6-monthly treatments are not sufficient to draw definitive conclusions.     

Blue Light Overrides Repression of Asexual Sporulation by Mating Type Genes in the Basidiomycete Coprinus cinereus

Monokaryotic mycelia of the homobasidiomycete Coprinus cinereus form asexual spores (oidia) constitutively in abundant numbers. Mycelia with mutations in both mating type loci (Amut Bmut homokaryons) also produce copious oidia but only when exposed to blue light. We used such an Amut Bmut homokaryon to define environmental and inherent factors that influence the light-induced oidiation process. We show that the Amut function causes repression of oidiation in the dark and that light overrides this effect. Similarly, compatible genes from different haplotypes of the A mating type locus repress sporulation in the dark and not in the light. Compatible products of the B mating type locus reduce the outcome of light on A-mediated repression but the mutated B function present in the Amut Bmut homokaryons is not effective. In dikaryons, the coordinated regulation of asexual sporulation by compatible A and B mating type genes results in moderate oidia production in light. Copyright 1998 Academic Press.