Sterols from three Lactarius species

The sterol composition of three fungi was determined. Ergosterol is the major sterol, accompanied by other closely related sterols.     

Inhibition of human seminal fluid and Leishmania donovani phosphatases by molybdate heteropolyanions

Inhibition of a tartrate-resistant acid phosphatase (ACP) from Leishmania donovani and the tartrate-sensitive ACP from human seminal fluid (prostatic ACP) was examined using a series of 13 molybdate-containing heteropolyanions. The heteropolyanions were divided into four groups based on the number of molybdenum atoms they contain: Group I, Mo4; Group II, Mo6-8; Group III, Mo12; Group IV, Mo18. Two of the four groups, those consisting of compounds that contain either an Mo4 unit or an Mo18 unit with a heteroatom in the central cavity, were potent inhibitors and exhibited the highest degree of selectivity against the leishmanial and seminal fluid ACPs. The inhibition of prostatic ACP by complex E2 could be completely reversed by dialysis. Little inhibition of the acid phosphatase, beta-glucuronidase, or alpha-mannosidase from human spleen was observed with complexes B' and E2. For the seminal fluid phosphatase, the Ki values obtained with arsenate and vanadate depended markedly on pH, suggesting that, unlike most other phosphatases, the conformation of the inhibitor binding site on human seminal fluid ACP is pH-dependent. Results of competition experiments performed with various inhibitor pairs indicated that complex D2 binds to the active site of prostatic ACP while complex M binds at some site on the enzyme that affects the active site. Binding of complex M also modifies the affinity of the enzyme for other inhibitors such as vanadate. The potency of several heteropolyanion complexes and their selective inhibition of pathophysiologically significant acid phosphatases indicate that these compounds may have value as tools for study of the structure and function of this class of enzyme and perhaps in the therapy of human disease.     

Psychophysical studies of the itch sensation and itchy skin ("alloknesis") produced by intracutaneous injection of histamine.

Psychophysical measurements of itch and itchy skin ("alloknesis"--itch produced by innocuous mechanical stimulation) were obtained in human volunteers following intracutaneous or subcutaneous injections of histamine or papain into the volar forearm. Histamine and papain were given in doses of 0.1, 1, or 10 micrograms in 10 microliters of saline. The effects of the depth of injection and of skin temperature on the latency, magnitude, and duration of itch were examined. Also, dose-response functions were obtained for the area of alloknesis produced by intracutaneous injections of histamine. Finally, the neural mechanisms underlying the spread of alloknesis were investigated via local anesthesia of the skin. Intracutaneous and subcutaneous injections of histamine, but not papain, produced a sensation of itch without pain. The latency of itch was shorter after an intracutanous than after a subcutaneous injection of histamine. The mean latencies of itch produced by a 1-microgram dose were 9.5 and 23.0 sec for intracutaneous and subcutaneous injections, respectively. No differences were observed in the magnitude or duration of itch. Similarly, the latency of itch was increased when the skin temperature at injection site was lowered to 15 degrees C, whereas the magnitude and duration of itch were unaffected. Intracutaneous and subcutaneous injections of histamine produced similar areas of alloknesis. However, the magnitude and duration of alloknesis were dependent on dose. The mean maximum areas of alloknesis produced by intracutaneous injections of 0.1, 1, and 10 micrograms of histamine were 28.3, 47.2, and 43.8 cm2, respectively. Alloknesis was present at 2 min after injection, increased to a maximum area without 10 min, and then gradually decreased during the next 25-40 min.(ABSTRACT TRUNCATED AT 250 WORDS)     

Révision systématiquedu genre Steginoporella smitt, 1873 (Bryozoa Cheilostomata)

Systematic revision of the genus Steginoporella: until now about eighty species were described. Only twenty recent species and thirty-four fossil ones are maintained. Several species and subspecies are new.The main interest of this revision is to establish a biostratigraphical scale: the settlement of this scale is based on the known stratigraphical distribution and on an attempt of phylogeny.The second advantage is ecological: all recent species live in marine tropical environment. The Steginoporella are good paleoecological indicators.At last, the establishment of a paleobiogeography, even incomplete and not definitive, allows to understand more easily recent distribution of Steginoporella connected with the great events of earth evolution.     

植被格局对砒砂岩坡地降雨侵蚀的影响

为进一步研究砒砂岩区不同雨型下植被格局对坡面土壤侵蚀特征的影响,基于野外径流小区原位观测试验与景观生态学相结合的方法,通过对比分析不同坡面的植被斑块格局指数与产流产沙之间的相关关系,阐明植被格局对砒砂岩坡地降雨侵蚀的影响。结果表明:(1)该地区降雨可划分为3类,根据各植被坡面产流产沙能力,得出降雨侵蚀力表现为:雨型II(长历时、大雨量、大雨强) ＞ 雨型III(短历时、小雨量、中雨强) ＞ 雨型I(中历时、中雨量、小雨强)。降雨量和最大30min雨强与产流产沙量呈显著或极显著关系,相关系数0.695以上,是预测该区域水土流失的主要降雨因子。(2)各坡面水土保持能力与降雨类型有关,不同雨型下3种植被坡面减流减沙率分别达0.42%、20.8%以上,不同植被格局坡面减沙效益优于减流效益,3种植被坡面的减流能力为:雨型I ＞ 雨型III ＞ 雨型II。(3)3种植被坡面的径流泥沙模数由小到大依次为:均匀分布 ＜ 聚集分布 ＜ 随机分布,对比区域多年平均径流泥沙模数,3种植被坡面能够减少侵蚀达21.33%以上。(4)景观形状指数和分离度指数是影响坡面产流产沙的主要格局因子,相关系数分别达0.884和0.825以上。产流、产沙量与坡面植被斑块分离度呈显著正相关,与景观形状指数呈显著负相关。坡面产流量(Y₁)与斑块分离度(SPLIT)和景观形状指数(LSI)的关系式为Y₁=8.247SPLIT-6.605LSI+38.928,R²=0.905。以上结果表明植被斑块间的分离度越小,形状越复杂,坡面阻力增大,抗侵蚀能力越强。研究成果可为生态恢复过程中植被斑块格局的优化提供理论依据和数据支撑。     

Recognition of the neural chemoattractant Netrin-1 by integrins alpha6beta4 and alpha3beta1 regulates epithelial cell adhesion and migration

Netrins, axon guidance cues in the CNS, have also been detected in epithelial tissues. In this study, using the embryonic pancreas as a model system, we show that Netrin-1 is expressed in a discrete population of epithelial cells, localizes to basal membranes, and specifically associates with elements of the extracellular matrix. We demonstrate that alpha6beta4 integrin mediates pancreatic epithelial cell adhesion to Netrin-1, whereas recruitment of alpha6beta4 and alpha3beta1 regulate the migration of CK19+/PDX1+ putative pancreatic progenitors on Netrin-1. These results provide evidence for the activation of epithelial cell adhesion and migration by a neural chemoattractant, and identify Netrin-1/integrin interactions as adhesive/guidance cues for epithelial cells.     

硝酸盐供应对玉米侧根生长的影响

以两个玉米(Zea mays L.)自交系478和Wu312为研究材料,采用琼脂培养方法,研究不同浓度NO-3对侧根生长的影响.结果表明,在外部浓度0.01～1.0mmol/L范围内,NO-3供应能显著增加侧根的长度及根生物量.但当NO-3供应超过1.0 mmo1/L后,侧根长度开始下降.当NO-3供应分别在超过5.0(Wu312)与10(478)mmol/L后,侧根密度显著下降.在10 mmol/LNO-3下,Wu312的侧根生长几乎完全被抑制.而478在20 mmol/L时,侧根密度仍可达到其最大值的30%(主根)～50%(胚根).植株地上部全氮及硝酸盐含量随NO-3供应的增加而升高,二者与侧根长度、侧根密度及冠根比的数学函数关系相同.     

Rational design of Salmonella-based vaccination strategies

A permanently growing body of information is becoming available about the quality of protective immune responses induced by mucosal immunization. Attenuated live bacterial vaccines can be administered orally and induce long-lasting protective immunity in humans without causing major side effects. An attenuated Salmonella enterica serovar Typhi strain is registered as live oral vaccine against typhoid fever and has been in use for more than two decades. Recombinant attenuated Salmonella strains are also an attractive means of delivering heterologous antigens to the immune system, thereby, stimulating strong mucosal and systemic immune responses and consequently provide an efficient platform technology to design novel vaccination strategies. This includes the choice of heterologous protective antigens and their expression under the control of appropriate promoters within the carrier strain. The availability of well-characterized attenuated mutants of Salmonella concomitantly supports fine tuning of immune response triggered against heterologous antigens. Exploring different mucosal sites as a potential route of immunization has to be taken into account as an additional important way to modulate immune responses according to clinical requirements. This article focuses on the rational design of strategies to modulate appropriate immunological effector functions on the basis of selection of (i) attenuating mutations of the Salmonella strains, (ii) specific expression systems for the heterologous antigens, and (iii) route of mucosal administration.