The Effect of Methionine Sulphoximine on the Absorption of Ammonium by Maize and Barley Roots over Short Periods

Pre-treating intact, ammonium-grown plants of maize and barleywith the glutamine synthetase inhibitor, L-methionine sulphoximine(MSO), increased subsequent accumulation of ¹³N or ¹⁵N fromlabelled ammonium very markedly—up to 8-fold in extremecases. The phenonemon could not be satisfactorily explainedin terms of an effect of MSO on the cation-exchange propertiesof the root free space, because neither potassium (⁸⁶Rb⁺) norsodium absorption was enhanced by MSO pretreatment, and rapidabsorption of ammonium continued for too long in relation tothe likely free-space content of a monovalent cation. Instead,the response is seen as a consequence of the enlargement ofthe cytoplasmic and vacuolar ammonium pools that occurs whenammonium assimilation is inhibited by MSO. The results, whichincluded comparisons between short-term and longer-term ratesof ammonium absorption, provide tentative evidence of rapidfluxes of ammonium through the plasma membrane. Key words: Cytoplasm, vacuole, flux, transport     

Waterfowl Nesting in Fall-Seeded and Spring-Seeded Cropland in Saskatchewan

Abstract: Waterfowl nesting in annual croplands has remained a little-known aspect of waterfowl nesting ecology because of the inability of many studies to systematically search this habitat through the nesting season. Where searches have been conducted, they are generally restricted to the period prior to seeding, and many nests found are destroyed by the seeding operation. Consequently, fall-seeded crops have been promoted as an alternative cropping practice that could increase nest survival of waterfowl nesting in croplands. During 1996–1999, we conducted 3–4 complete nest searches on 4,274 ha of cropland, including spring-seeded wheat and barley, winter wheat, and fall rye in southern Saskatchewan, Canada. Using suites of predictive models, we tested hypotheses regarding relative nest abundance and nest survival among crop types and tested the influence of several landscape-scale covariates on these metrics. Apparent nest densities were higher in fall-seeded crops (winter wheat: 0.39 nests/ha, fall rye: 0.25 nests/ha) than in spring-seeded crops (0.03 nests/ha), and nest density in spring-seeded croplands increased with percent cropland and percent wetland habitat in the surrounding landscape. Nest survival was higher in winter wheat (38%) than in either fall rye (18%) or spring-seeded crops (12%), and nest survival in spring-seeded crops increased with relative nest initiation date. Nest survival was unaffected by surrounding landscape characteristics but tended to be higher in years of average wetness. Based on our findings, winter wheat and fall rye have the potential to provide productive nesting habitat for ≥7 species of upland nesting ducks and fall-seeded crops are a conservation tool well suited to highly cropped landscapes.     

Review of the East Asian species of the genera Hybrizon Fallén and Ghilaromma Tobias (Hymenoptera: Ichneumonidae: Hybrizontinae)

East Asian species of the genera Hybrizon and Ghilaromma are reviewed. Four species of Hybrizon, H. buccatus (Brébisson 1825), H. ghilarovi Tobias, 1988, H. juncoi (Ceballos 1957) and H. flavofacialis Tobias, 1988 and two species of Ghilaromma, G. orientalis Tobias, 1988 and G. ussuriensis Tobias, 1988, were recognized. H. ghilarovi was recorded from Korea, Japan and China, while H. juncoi was recorded from Korea, for the first time. The specimens recorded from Japan as G. fuliginosi (Wilkinson, 1930) by Watanabe (1984) are referred to G. orientalis herein. This species is newly recorded from Korea and Japan. Keys to East Asian species of Hybrizon and the world species of Ghilaromma are also provided.     

人精液凝固蛋白SgI-52的表达与抗菌活性研究

以人精囊腺cDNA为模板,用嵌套式PCR技术扩增出编码成熟人精液凝固蛋白I(semenogelin I,SgI)第85–136位氨基酸(SgI-52)的核苷酸序列并将其插入载体pMAL-p2X中,成功构建的表达载体pMAL-p2X/SgI-52转化大肠杆菌DH5α后,重组融合蛋白诱导表达于大肠杆菌周质中。经第X因子剪切及超滤处理,得到表达的重组SgI-52。质谱分析结果证明重组SgI-52为目的肽。重组人SgI-52对大肠杆菌ATCC25922标准株以及耐氨苄标准株ML-35P的最低抑制浓度MIC分别为32.45以及46.30?μg/mL。我们的结果及相关研究提示在人精液液化过程中人精液凝固蛋白I的不同降解产物可能行使不同的生物学功能,值得进行深入研究。     

Flight periodicity and infestation size of Sitona lineatus

Sitona lineatus displays two distinct flight periods; a post-teneral flight in the late summer and a post-diapausal flight in the spring. The late summer flight begins as soon as adults start to emerge from pupal cells during late July and continues until mid-October. Maximum aerial density is observed in late August. Less than 10% of newly emerged adults leave the crop by flight, the rest remain in the soil or move to overwintering sites by walking. Spring flight begins in late March if temperatures are above the 12.5°C flight threshold and reaches a peak in mid-April. Most migratory flight is downwind. Little trivial flight occurs and once individuals have located a crop, redistribution is by walking. Laboratory studies indicate that adults fly most often during the day, particularly at noon. The size of infestations appeared to be independent of the area of legumes grown in a locality with large differences occurring even between neighbouring fields. Examination of the yields of field experiments at Rothamsted demonstrate an unexpected trend for higher yields in later sown spring bean crops. This may be because late sowing avoids infestation by spring migrants.     

First record of the family Embolemidae (Hymenoptera: Chrysidoidea) from Korea

The family Embolemidae Westwood, 1833 is recorded for the first time in Korea, based on a species Embolemus ruddii Westwood. A diagnosis of this species complemented by digital images are provided.