Effect of a membrane interactive peptide on plant cells of canola (Brassica napus) and two fungal pathogens

Summary A membrane interactive peptide was toxic to microspores, pollen and protoplasts of canola in the 1–5 µM concentration range. Similarly, at 5.0 µM the peptide completely inhibited germination of conidia ofVerticillium albo-atrum; however, when tested with conidia of a virulent isolate of blackleg (Leptosphaeria maculens), a fungal pathogen of canola, much higher levels (>30 µM) of the peptide were required to reduce or arrest germination and growth of the conidia. When testing the relative toxicities of novel peptides on plant cells and their pathogens, pollen germination is a simple, rapid and reliable alternative to protoplasts.     

Crosslinking of uteroglobin by transglutaminase

Uteroglobin, a progesterone induced, pregnancy related protein, can be incorporated into higher molecular weight proteins by human placental Factor XIIIa. This process is time dependent, requires CaCl2 and can be inhibited by the addition of polylysine, dansylcadavarine or histamine. Crosslinking of uteroglobin into higher molecular weight proteins can also be brought about by guinea pig liver transglutaminase. Such a process may be involved in the modification of epididymal spermatozoa to suppress their antigenicity.     

Lysis of bacterioids in the vicinity of the host cell nucleus in an ineffective (fix-) root nodule of soybean (Glycine max)

In nodules of Glycine max cv. Mandarin infected with a nod ⁺fix^- mutant of Rhizobium japonicum (RH 31-Marburg), lysis of bacteroids was observed 20 d after infection, but occurred in the region around the host cell nucleus, where lytic compartments were formed. Bacteroids, and peribacteroid membranes in other parts of the host cell remained stable until senescence (40d after infection). With two other nod⁺ fix^- mutants of R. japonicum either stable bacteroids and peribacteroid membranes were observed throughout the cell (strain 61-A-165) or a rapid degeneration of bacteroids without an apparent lysis (strain USDA 24) occurred. The size distribution of RH 31-Marburg-infected nodules exhibited only two maxima compared with four in wild-type nodules and nodule leghaemoglobin content was found to be reduced to about one half that of the wild type. The RH 31-Marburg-nodule type is discussed in relation to the stability of the bacteroids and the peribacteroid membrane system in soybean.     

Factor analysis in clusterbean (Cyamopsis tetragonoloba (L.) Taub)

Summary The pattern of diversity in forty genotypes of clusterbean (Cyamopsis tetragonoloba (L.) Taub) was analysed using the centroid method of factor analysis based on nine characters. Three factors were found to adequately account for most of the intercorrelations in the four environments. Branches, clusters, pods and seed yield/plant could be grouped as productivity factors; days to flowering, maturity and plant height as growth factors; seeds/pod and gum content as economic factor. Interestingly, the constitution of the factors were the same in all the environments. The loadings on the economic factors were relatively unstable, whereas the loadings on productivity and growth factors were stable. It is concluded that productivity and growth factors play a pivotal role towards diversity in clusterbean. The results of factor analysis provides confirmatory evidence of diversity in clusterbean, which was earlier studied by using generalized distance, and thus proves the adequacy of the centroid method in biological investigations.     

Population dynamics of the swallowtail butterfly,Papilio xuthus L., in a deforested area

The long-term population dynamics of the swallowtail butterfly, Papilio xuthus, were studied by means of life table analysis in a deforested area, where the host tree, Zanthoxylum ailanthoides, was growing. The number of eggs laid on host trees in the deforested area decreases as secondary succession progresses. When the trees were classified into three groups, i. e. tall, medium and short, according to their height relative to the surrounding vegetation, less eggs were laid on tall than on short host trees. Life tables for the natural populations in each generation were developed on the basis of mean values for 6 years. Eggs and larvae in early stages were attacked chiefly by small- and middle-sized predators, such as ants, spiders, bugs and orthopterids, while later stage larvae were attacked chiefly by birds or Polistes wasps. An inchneumonid wasp was the most important mortality factor in the pupal stage. Key-factor analysis was tested on the life table data of each immature stage. The late larval stage was a key stage, and most mortality factors were considered to operate independently. The test for density dependency did not show any tendencies. The analysis of variance in two-way classifications was carried out for the difference of survival rate among the tree groups. It was suggested that tall host trees were unsuitable for P. xuthus. The construction of life tables for artificially inoculated populations on large host trees showed that high physiological death rate were characteristic of such trees in comparison with natural populations on smaller trees. The characteristics of the population dynamics of P. xuthus in the deforested area are compared among some kinds of the habitat, and the interrelationship between P. xuthus and its host plant are discussed.     

Enhanced in vitro growth of murine fibroblast cells and preimplantation embryos cultured in medium supplemented with an amphipathic peptide.

Preliminary studies on the proliferative effects of lytic peptides were carried out using NIH 3T3 murine fibroblast cells and human lymphocytes. Cells were cultured in various concentrations of three different amphipathic peptides (SB-37, Shiva-1, and Vishnu), and enhanced proliferation was determined by uptake of 3H-thymidine with treated cells compared with control cultures. Enhanced proliferation of 3T3 cells was observed in cultures containing 50 microM or less SB-37. The primary study consisted of 263 four-cell- to eight-cell-stage mouse embryos from naturally bred mice and incubated in Whitten's medium containing 0.2, 1, or 10 microM of the amino terminus of an amphipathic cecropin B analog (Vishnu) or in Whitten's medium alone. Embryos were cultured to the hatched blastocyst stage, and effect of treatment was determined by the rate of growth to that stage of development. Statistical analysis revealed that culture in all three levels of Vishnu significantly accelerated in vitro growth of these stages of preimplantation embryos compared with controls. These results indicate that Vishnu promotes increased cleavage rates of embryos in vitro. A growth factor receptor clustering mechanism of action is proposed. This peptide may have some potential as an embryo culture medium additive to enhance in vitro growth rate.     

Nerve Growth Factor: Biological Significance, Measurement and Distribution

NGF proteins probably act as informational molecules transferred from end organs to the neurons of the sympathetic nervous system. The direct demonstration of the NGF content of most end organs requires assays more sensitive than those currently available. The high levels of NGF produced by some organs are probably of some other physiological significance.     

A factor analysis of body build in the rat

Following a survey of the problems associated with the comparative study of measures of physique in domesticated and laboratory animals, techniques were developed for the measurement of body build in the adult albino laboratory rat (Rattus norvegicus). They involved anesthetisation of the animals and the use of calipers and a simple apparatus devised for the purpose. The 17 measures taken on 100 rats, 50 of each sex, are detailed and the reasons for excluding others given. Intercorrelations of all the measures and their reliability co-efficients, which were judged satisfactory, are presented. The tables of intercorrelations, one for each sex, were factor analysed separately, and rotations to simple structure performed. Two factors were identified, one having factor saturations on measures of body length and the other similarly defining body width. This pattern was similar for the two sexes and a single index of body build was therefore proposed in which the length of the rear foot is divided by the width of the shoulder girdle and multiplied by 100 to avoid decimals. The use of the index in other investigations is mentioned.     

Methylation of TMV RNA

Several plant and animal viral RNAs contain a tRNA like structure at their 3′ ends. In this communication we show that tobacco mosaic virus (TMV) RNA is an acceptable substrate for a specific tRNA methyltransferase. Using a crude preparation of $\text{E. coli}$ ribothymidine (rT) forming uracil methylase and (methyl ³H) S-adenosyl-L-methionine (SAM) as a methyl donor, 0.7 moles of methyl group is incorporated per mole of TMV RNA in 10 hours at 30°C. Upon T₂ RNAse digestion of the labeled RNA, all of the radioactivity was found to be in TMP. T₁ RNAse digestion of ³H methylated TMV RNA showed that all of the label was located in a tetranucleotide which co-migrated with authentic TpψpCpGp, an oligonucleotide characteristically found in normal cellular tRNA.The use of this specific methyl transferase reaction may provide a simple assay for the detection of tRNA like structures in large RNAs.     

A factor analysis of morphogenetic fields in the human dentition

The traditional morphogenetic fields of the human dentition were evaluated by means of factor analysis of dental dimensions taken from a series of human crania. When crown length, crown width and crown index were considered separately, factors emerged which could be identified with the tooth group fields. But a combined crown length-crown width analysis generated factors which extended beyond the regional tooth groups. Crown width itself was revealed to be an important axis of morphologic intergration. It was concluded that univariate methods are not adequate for identifying morphogenetic fields; the teeth must be treated as multidimensional units where the correlation among dimensions is accounted for.