人体单臂间歇运动对发汗调定点的影响

本工作系在微小气候相对恒定条件下,对10名健康男青年每人进行四项实验。实验 Ⅰ 为测定双侧腿足浸入43℃水中,诱发左前臂屈侧显现定量汗点时的口腔温度(舌下)阈值,作为发汗调定点参考值(ToSSP);实验 Ⅱ 为 Ⅰ 附加右臂间歇轻负荷运动(77W)时测定 ToSSP,部分对象还记录了皮肤电反应;实验 Ⅲ、Ⅳ 为 Ⅰ、Ⅱ 均附加4.5m/s 气流(22—25℃)直吹头面部,再分别测定 ToSSP。实验 Ⅰ 与 Ⅱ 同体对照22人次,Ⅲ 与 Ⅳ 同体对照24人次。结果表明,实验 Ⅱ、Ⅳ 的 ToSSP 均值及其潜伏期均值分别较 Ⅰ、Ⅲ 者降低(P<0.01)或缩短(P<0.001);Ⅰ、Ⅱ间的 ToSSP 均值差、潜伏期均值差,分别与 Ⅲ、Ⅳ 之间者无显著差异(P>0.2);Ⅱ、Ⅳ 的ToSSP 均值各与其实验开始前的口温均值亦无明显差异(P>0.5)。此结果支持运动时体温调定点下降的论点,并提示在研究体温调定点活动时,以 ToSSP 为指标较用发汗速率为优越,因 ToSSP 不为许多干扰因素所影响。     

Identification and functional analysis of two U3 binding sites on yeast pre-ribosomal RNA.

It has long been known that U3 can be isolated hydrogen bonded to pre-ribosomal RNAs, but the sites of interaction are poorly characterized. Here we show that yeast U3 can be cross-linked to 35S pre-rRNA both in deproteinized extracts and in living cells. The sites of cross-linking were localized to the 5' external transcribed spacer (ETS) and then identified at the nucleotide level. Two regions of U3 near the 5' end are cross-linked to pre-rRNA in vivo and in vitro; the evolutionarily conserved box A region and a 10 nucleotide (nt) sequence with perfect complementarity to an ETS sequence. Two in vivo cross-links are detected in the ETS, at +470, within the region complementary to U3, and at +655, close to the cleavage site at the 5' end of 18S rRNA. A tagged rDNA construct was used to follow the effects of mutations in the ETS in vivo. A small deletion around the +470 cross-linking site in the ETS prevents the synthesis of 18S rRNA. This region is homologous to the site of vertebrate ETS cleavage. We propose that this site may be evolutionarily conserved to direct the assembly of a pre-rRNA processing complex required for the cleavages that generate 18S rRNA.     

我国恙虫蚴的三个新种(蜱螨目, 恙虫科)

近几年来,我国科学家们在恙虫方面的研究工作巳经取得了显著的成就。然而,这对于拥有辽阔疆土的我国来说,实在只不过是一个开始。我们在这方面的工作也做得很少,虽然从1953年开始收集标本,由于各种条件所限制,未能及时整理,以致大量标本散失或霉烂,十分可惜。本文内容,仅仅是将我站恙虫病调研工作组1957年在本省各地所采集的材料中的三种恙虫蚴加以描述,该三种恙虫蚴均系文献上未曾记载过的种类。     

Mutational analysis of an essential binding site for the U3 snoRNA in the 5' external transcribed spacer of yeast pre-rRNA.

The small nucleolar RNA U3 is essential for viability in yeast. We have previously shown that U3 can be cross-linked in vivo to the pre-rRNA in the 5' external transcribed spacer (ETS), at +470. This ETS region contains 10 nucleotides of perfect complementarity to U3. In a genetic background where the mutated rDNA is the only transcribed rDNA repeat, the deletion of the 10 nt complementary to U3 is lethal. Cells lacking the U3 complementary sequence in pre-rRNA fail to accumulate 18S rRNA: pre-rRNA processing is inhibited at sites A0 in the 5' ETS, A1 at the 5' end of 18S rRNA and A2 in ITS1. We show here that effects on processing at site A0 are specific for U3 and its associated proteins and are not seen on depletion of other snoRNP components. The deletion of the sequence complementary to U3 in the ETS therefore mimics all the known effects of the depletion of U3 in trans. This indicates that we have identified an essential U3 binding site on pre-rRNA, required in cis for the maturation of 18S rRNA.     

Base pairing between U3 and the pre-ribosomal RNA is required for 18S rRNA synthesis.

The nucleolus, the site of pre-ribosomal RNA (pre-rRNA) synthesis and processing in eukaryotic cells, contains a number of small nucleolar RNAs (snoRNAs). Yeast U3 snoRNA is required for the processing of 18S rRNA from larger precursors and contains a region complementary to the pre-rRNA. Substitution mutations in the pre-rRNA which disrupt this base pairing potential are lethal and prevent synthesis of 18S rRNA. These mutant pre-rRNAs show defects in processing which closely resemble the effects of genetic depletion of components of the U3 snoRNP. Co-expression of U3 snoRNAs which carry compensatory mutations allows the mutant pre-rRNAs to support viability and synthesize 18S rRNA at high levels. Pre-rRNA processing steps which are blocked by the external transcribed spacer region mutations are largely restored by expression of the compensatory U3 mutants. Pre-rRNA processing therefore requires direct base pairing between snoRNA and the substrate. Base pairing with the substrate is thus a common feature of small RNAs involved in mRNA and rRNA maturation.     

红汁乳菇醇提物对水稻、稗草的化感影响

研究了红汁乳菇子实体乙醇抽提物对水稻、稗草的化感影响。用不同浓度的红汁乳菇子实体乙醇抽提物处理水稻和稗草种子 ,测量处理后不同时间的水稻和稗草幼苗的根长和苗高 ,按照 Willamson,G.B.的方法计算化感作用效应 (RI)。结果表明 :红汁乳菇乙醇抽提物对稗草幼苗的生长有显著的抑制作用 ,能够导致稗草叶片发黄 ,缩短稗草的根和苗 ,甚至延迟部分种子的萌发。其中 8.5 mg/ ml的乙醇抽提物处理稗草种子后 3d、8d,对根长的化感作用效应分别为 - 0 .98、- 0 .5 8;对苗高的化感作用效应分别为 - 0 .5 0、- 0 .5 1。 6 .5 m g/ ml和 10 .5 mg/ ml处理组的结果与 8.5 mg/ ml处理组的结果在 p=0 .0 5水平上差异不显著。对水稻幼苗的生长表现出一定的调节作用 ,在较低浓度下 (≤ 4 .5 0 mg/ m l)对水稻幼苗有一定促进作用 ,如 4 .5 0 m g/ ml处理水稻种子后 3d、8d,对苗高的化感作用效应分别为 0 .2 5、0 .10 ;在较高浓度下 (如≥ 6 .5 0 mg/ ml)对水稻根长和苗高均为抑制作用 ,6 .5 0 mg/ ml时抑制作用最强 ,处理水稻种子后 3d、8d对幼苗的根长的化感作用效应分别为 - 0 .93、- 0 .4 8;对苗高的化感作用效应分别为 - 0 .5 0、- 0 .2 2 ,在 p=0 .0 5水平上与其它处理组差异显著     

细菌素的合成与作用机制

细菌素是由细菌产生的抗菌蛋白,可以杀死与产生菌相近的细菌。很多乳酸菌产生不同多样性的细菌素,虽然这些细菌素都是由发酵或非发酵食品中发现的乳酸菌产生的,但是迄今只有乳酸链球菌素(Nisin)作为食品防腐剂被广泛应用。和抗生素不同的是,细菌素由核糖体合成,需经翻译后修饰活化并且通过特定转运系统输到胞外才能发挥其功能,它一般通过作用于靶细胞膜来抑制靶细胞的生长,同时本身合成细菌素的细胞对其产物具有免疫性。细菌素能安全有效地抑制病原体生长,在食品行业中具有广阔的应用前景。     

动物及其肠道菌群的协同进化研究

动物自身合成一些关键营养物质的能力缺失,转而依赖体内的共生物来完成相应功能,如动物体内共生细菌能帮助宿主从食物中提取营养物质,并能合成一些关键代谢反应的化合物。结合国内外在动物及其肠道菌群的协同进化的研究进展,从三个方面进行了归纳:(1)动物及其肠道微生物组成与功能的协同进化研究;(2)动物行为与肠道微生物的关系;(3)共生肠道微生物在人类或动物自身消化食物、营养获取、健康和疾病方面发挥的重要作用。     

大树蛙与斑腿树蛙的繁殖与驯养

1997～2000年,在广州动物园生态蛙蟾馆观察与研究了笼养条件下大树蛙和斑腿树蛙的繁殖行为和驯养过程,比较了两种树蛙繁殖生态的差别。