外域杂草的产生、传播及生物与生态学特性的分析

本文分析了浙江省境内较近期传入的外域杂草区系成分,介绍了我国一些常见外域杂草的产生及传播特点,并通过对北美车前（Ｐｌａｎｔａｇｏｖｉｒｇｉｎｉｃａ）繁殖机制,种群生态、分布及危害特点等方面的研究．阐述了外域杂草所具的生物与生态学特性．     

脑干内的混沌

对脑干听觉诱发电位进行了非线性动力学分析,计算了关联维数Ｄ２和最大Ｌｙａｐｕｎｏｖ特征指数,确认ＢＡＥＰ是一个来源于低维混沌动力系统的时间序列,从而证明人类脑干存在着混沌现象,利用满足最小互信息标准的最佳延迟重构了二维混沌吸引子。     

Reproductive performance, population dynamics and anthropometrics of the free-ranging Cayo Santiago rhesus macaques

This report summarizes demographic data collected on the Cayo Santiago colony of rhesus monkeys from 1976-1983 and compares the results with those from 1959-1964 [8,9]. For males and nonpregnant/nonlactating, pregnant, and lactating females mean (+/- 1 SD), body weights, crown-rump lengths, and ponderal indices are tabulated for each age on a large (n = 586) single sampling of this free-ranging population of macaques.     

Assessment of a model for intron RNA secondary structure relevant to RNA self-splicing--a review

A widespread class of introns is characterized by a particular RNA secondary structure, based upon four conserved nucleotide sequences. Among such "class I" introns are found the majority of introns in fungal mitochondrial genes and the self-splicing intron of the large ribosomal RNA of several species of Tetrahymena. A model of the RNA secondary structure, which must underlie the self-splicing activity, is here evaluated in the light of data on 16 further introns. The main body or "core structure" of the intron always consists of the base-paired regions P3 to P9 with the associated single-stranded loops, with P2 present also in most cases. Two minority sub-classes of core structure occur, one of which is typical of introns in fungal ribosomal RNA. Introns in which the core structure is close to the 5' splice site all have an internal guide sequence (IGS) which can pair with exon sequences adjacent to the 5' and 3' splice sites to align them precisely, as proposed by Davies et al. [Nature 300 (1982) 719-724]. In these cases, the internal guide model allows us to predict correctly the exact location of splice sites. All other introns probably use other mechanisms of alignment. This analysis provides strong support for the RNA splicing model which we have developed.     

Relationship between collagen fibril diameters and body size

Summary Suspensions of collagen fibrils obtained from derma of Elasmobranchia and Actinopterygia of different body sizes and developmental stages were examined by transmission electron microscopy. Fibril diameters were measured and classified into groups comprising a 20 nm diameter interval. Diagrams showing fibril populations of each fish were made. The measurements were averaged and their confidence intervals and standard errors determined. For each species other diagrams were plotted in which the mean diameters were correlated to the body length of each sample. The results show that: 1) a correlation exists between an increase in diameter of collagen fibrils and somatic growth until sexual maturity is reached; 2) fibril populations are subsequently spread over a wider range due to the presence in the derma of classes of newly formed and therefore thinner fibrils. The deposition of new fibrils is possibly influenced by individual factors; 3) no relationship exists between mean fibril diameter and body size; 4) no relationship exists between phylogenetic position and pattern of diameter distribution.Research supported by a grant from C.N.R. Roma (69.02087.0115.1150)     

The relative importance of prenatal and postnatal maternal influences on growth in mice

Summary The cross-nursing technique was used to assess the relative importance of prenatal and postnatal maternal influences on growth in mice from an unselected population originated from a cross of four highly inbred strains. Body weights were studied at birth, 7-, 14-, 21- and 42-days, in addition to the weight gains between these ages and tail length at 21 and 42 days of age. At littering, each dam in each nursing set retained two of her own offspring and two were transfereed to each of the other dams in the set, so that each nursed litter contained six young representing three mothers. Prenatal influences accounted for 37, 15, 10, 11 and 13 % of the total variation in the respective body weights, while postnatal influences accounted for 0, 64, 65, 49 and 14% at the respective ages. In the case of weight gains, prenatal influences were responsible for 16, 4, 6 and 30%, while postnatal influences were responsible for 66, 66, 31 and 7% of the total variation in gain during the respective four periods examined. Apparently the individual weight gain from 7 to 14 days was a better measure of the lactational performance of the dam than individual 14-day weight. For tail length, prenatal influences accounted for 6 % and 4 % of the total variation in tail length at 21 and 42 days, respectively, while postnatal influences accounted for 60 % and 24 % at the respective ages. Generally, there was no indication of an important interaction between the nurse and the nursed young at any stage studied.     

Direct and maternal genetic effects on body weight maturing patterns in mice

Summary Direct and maternal genetic effects were evaluated for maturing patterns of body weight in mice using a crossfostering design. Crossfostering was performed in one group using dams from populations selected for rapid growth rate (M16 and H₆) and their reciprocal F₁. crosses. A second crossfostering group consisted of dams from the respective control populations (ICR and C₂) and their reciprocal F₁. 's. Population differences were partitioned into direct and maternal effects due to genetic origin, correlated selection responses, heterosis and cytoplasmic or sex-linked effects. Degree of maturity was calculated at birth, 12, 21, 31 and 42 days of age by dividing body weight at each age by 63-day weight. Absolute and relative maturing rates were calculated in adjacent age intervals between birth and 63 days. Genetic origin effects (ICR vs. C₂; M16 vs. H₆) were significant for many maturity traits, with average direct being more important than average maternal genetic effects. In general, correlated responses to selection for maturity traits were larger in the M16 population (M16 vs. ICR) than in the H₆ population (H₆ vs. C₂) and correlated responses in average direct effects were larger than average maternal effects. Positive correlated responses in average direct effects were found for relative maturing rates at all ages and for absolute maturing rates from 31 to 63 days. Apparent correlated responses in degree of maturity were negative for M16 and H₆. However, further analysis suggested that the correlated response for degree of maturity in H₆ may be positive at later ages and negative at earlier ages. Direct and maternal heterosis for degree of maturity was positive in the selected and control crosses. Absolute and relative maturing rates showed positive heterosis initially, followed by negative heterosis. Reciprocal differences due to the cytoplasm or sex-linkage were not important for patterns of maturity.Paper No. 5244 the Journal Series of the North Carolina Agricultural Experiment Station, Ealeigh, Animal Research Institute Contribution No. 683 and Agricultural University at Wageningen Contribution No. 654–490–12On leave from the Animal Research Institute, Agriculture Canada at Ottawa, OntarioOn leave from the Department of Animal Husbandry, Agricultural University at Wagenitgen, the Netherlands     

机械损伤对9种水生植物叶片的影响

水生植物叶片的功能性状特征与陆生植物有所不同,同时叶脉类型也显著影响叶片的功能性状。本研究选取9种具有不同叶脉类型的水生植物,通过对叶脉进行直接损伤,分析叶片性状（形态、色素含量和叶绿素荧光指标）在叶脉受损后的变化程度与叶脉类型的关系。结果显示：具有平行脉的3种水生植物对叶脉损伤具有较强的耐受性;具羽状脉的4种植物主脉受损后显著抑制叶片生长,而侧脉受损的影响在不同物种间有所不同,具有物种特异性。本研究可为大型湖泊水生植物修复的水生物种筛选提供参考。