Different structure of polytene chromosomes ofPhaseolus coccineus suspensors during early embryogenesis

Summary The pattern of DNA and RNA puffs in pair VII of polytene chromosomes has been investigated in the suspensor ofPhaseolus coccineus during early embryo development. The pattern of³H-TdR and³H-U incorporation has been also detected. Collected data indicate that: 1. both heterochromatic regions, p₁₁ and q_(111+112), of chromosome pair VII, organize large DNA puffs; 2. DNA puffs of both regions are specific of different embryo differentiation steps; 3. a seasonal influence on the DNA puffing seems also to be present, as demonstrated by the comparison of the results collected in two different crops; 4. the incorporation experiment by³H-TdR evidences that not all DNA puffs show clustered labeling; 5. the RNA puffing of the two regions seems also to be specific of determined embryo stages.     

Electrophoretic elution of nucleic acids from acrylamide and agarose gels

A simple method for electrophoretic elution of nucleic acids from gel slices is described. The procedure utilizes a standard tube gel system and can be completed in as little as one hour. Nucleic acids are recovered in a small volume with almost 100% efficiency. The procedure is applicable equally to acrylamide and agarose gels, and small as well as large RNA and DNA molecules. The eluted nucleic acids are essentially undegraded and are suitable for a variety of structural and biological analyses.     

In vitro incorporation of 2′-deoxyadenosine and 3′-deoxyadenosine into yeast tRNAPhe using tRNA nucleotidyl transferase,and properties of tRNAPhe-C-C-2′dA and tRNAPhe-C-C-3′dA

2′-Deoxyadenosine and 3′-deoxyadenosine (cordycepin) can be incorporated into the 3′-terminal position of tRNA^Phe by tRNA nucleotidyl transferase. tRNA^Phe-C-C-2′dA and tRNA^Phe-C-C-3′dA, missing the cis-diol group at the 3′-terminal end are resistant to periodate oxidation and are not able to form borate complexes. In aminoacylation experiments only the tRNA^Phe-C-C-3′dA proved to be chargeable.     

Nucleic Acids of Entamoeba histolytica

This review will concentrate on certain aspects of the nucleic acids of Entamoeba histolytica. Utilization and synthesis of purines and pyrimidines will initially be briefly discussed, e.g. salvage vs. de novo pathways, uptake studies and recognition of at least 4 transport loci. Data will be presented which show that the distribution and synthesis of RNA (to a lesser extent DNA) in the nucleus is basically the opposite one finds in other eukaryotes, viz. most RNA (ribosomal?) is synthesized (or accumulates) in the peripheral chromatin (functional equivalent of nucleolus?). The DNA is distributed and synthesized primarily throughout the nucleus. It is usually so dispersed that it will not stain with e.g. the standard Feulgen technique, unless the DNA condenses around the endosome (not a nucleolar equivalent) prior to nuclear division. Isolation of rRNA was difficult due, in part, to potent and difficult to inhibit RNase(s), some of which are apparently intimately bound to ribosomal subunits. The 25S (1.3 kDa), 178 (0.8 kDa) and 58 rRNA were recovered after isolation with a high salt SDS-DEP technique. This is the only procedure which enables us to obtain high yields of 258 rRNA: guanidine or guanidinium which permits isolation of intact functional mRNA results in isolation of small amounts of 28 RNA relative to 178 RNA. The 258 RNA is “nicked” (apparently during nuclear processing) and dissociates readily into 1 78 (0.7 kDa) and 168 (0.6 kDa) species, and a more rigidly bound 5.88 species. A small amount of “unnicked” 258 RNA was recovered with guanidine. Two DNA-dcpendent RNA polymerases (I and II) with a pronounced preference for denatured DNA as template were eluted from DEAE-Sephadex in reverse order of what occurs in other eukaryotes, except Physarum polycephalum. This conclusion was based on salt optima and alpha-amanitin sensitivity studies. Initial characterization of DNA isolated with a procedure capable of isolating > 100-kbp Leishmania DNA showed that undigested DNA migrates as a broad band between markers 6 and 24 kbp. The persistent recovery of such a “band” by us and Perez-Mutul et al. no larger than ca. 24 kbp (with the exception of >48 kbp DNA isolated by Hernandez et al. using an in situ lysis technique which did not include a proteinase) may be due to nicks introduced during isolation; or, perhaps much of the amebal DNA exists in vivo as gene sized fragments. However, preliminary data generated using orthogonal pulse-field agarose gel electrophoresis do suggest that amebal DNA may be in small chromosomes.     

Functions and social consequences of infant–adult male interaction in a captive group of lowland gorillas (Gorilla gorilla gorilla)

The functions and social consequences of infant-adult male interaction in a captive group of lowland gorillas were evaluated. The two males repeatedly attempted to interact with the infant, the infant sometimes attempted to interact with the males, and the mother usually interrupted interactions between male and infant. Infant-directed actions by the two males frequently showed their interest in the infant and infrequently showed care giving toward her; their other infant-directed actions occurred near the time of excitement or of playful actions between adults. Male-directed actions by the infant frequently showed its interest in one male and infrequently showed care seeking from him. All infant-adult male interactions but one occurred in the less stimulating of the gorillas' two enclosures. Boredom and the mother's frequent thwarting of contact between a male and infant are suggested as influences on the males' interest in the infant. The data suggest that availability of interesting objects alleviated the boredom of captivity for males and thus dissuaded them from seeking stimulation which sometimes resulted in harmful behaviors toward the infant.     

Statistics of RNA melting kinetics

We present and study the behavior of a simple kinetic model for the melting of RNA secondary structures, given that those structures are known. The model is then used as a map that. assigns structure dependent overall rate constants of melting (or refolding) to a sequence. This induces a landscape of reaction rates, or activation energies, over the space of sequences with fixed length. We study the distribution and the correlation structure of these activation energies. Correspondence to: P. Schuster     

Biotype-specific expression of dsRNA in the sweetpotato whitefly

This study was conducted to evaluate the effect of two different biotypes of the sweetpotato whitefly,Bemisia tabaci (Gennadius), on the induction of squash silverleaf (SSL), and to determine if double-stranded RNA (dsRNA) occurs in geographically remote populations of the two biotypes. Recently collected B-biotype whiteflies from Florida, Arizona, Mississippi, and Texas (SPW-B) all contained a 7.0 kb dsRNA molecule. Kb dsRNA molecule. Laboratory colonies of A-biotype whiteflies that were originally collected in 1981 from cotton in Arizona and California did not contain the 7.0 Kb dsRNA. When the two biotypes were compared only the SPW-B induced rapid onset, grade 5, SSL. DsRNA similar to that found in adult SPW-B was concentrated in whitefly nymphs, but host plant leaf tissue did not contain any consistent dsRNA molecules. SPW-A only induced low-grade SSL and progeny of SPW-A that were fed on pumpkin plants displaying SSL did not acquire the ability to express dsRNA or induce SSL. Our data suggest that dsRNA is not directly involved in the induction of SSL and that SSL is a host-specific response, to a feeding injury induced by B-biotype whiteflies. The origin and source of the 7.0 Kb dsRNA molecule remains enigmatic but its expression is constant in the whitefly biotype that is responsible for the induction of SSL and several other plant disorders in the U.S.     

Response of root mRNA population to sulphate shortage in maize seedlings

Roots of ten-days-old seedlings obtained from a maize hybrid grown in complete or in sulphate-deprived medium were used to extract Poly(A)+RNA. The response to sulphate deprivation, which is known to increase the uptake capacity up to ten times, was manifested also by the expression of three mRNA species, as shown by the in vitro translation of the mRNA population. One hour after transfer to complete nutrient medium all three mRNAs were still present.Abbreviations BSA Bovine Serum Albumine - DTT 1,4-Dithio-DL-Threitol - EDTA Ethylenediaminetetraacetic-acid - MES 2-(N-Morpholino) ethane sulfonic acid - SDS Sodium Dodecyl Sulfate - TCA Trichloracetic acid - TRIS Tris(hydroxy-methyl)-aminomethane     

铽离子与RNA的荧光反应及RNA测定的研究

核糖核酸（ＲＮＡ）与稀土铽离子在ｐＨ５．０～６．５条件下能形成具有较强荧光的络合物,其激发峰在２８８ｎｍ处,发射峰为４９４ｎｍ及５４５ｎｍ处．ＲＮＡ在０．１～１０ｍｇ／Ｌ范围内与其荧光强度呈线性关系,其检出限为６．０×１０￣（－８）ｍｏｌ／Ｌ．腺苷酸,尿苷酸,胞苷酸对ＲＮＡ的干扰比较小,因此可在其存在下选择性地测定ＲＮＡ．