Prevalence of gene sequences coding for hypervariable regions of Opa (protein II) in Neisseria gonorrhoeae

Opas (protein IIs) are a family of surface-exposed proteins of Neisseria gonorrhoeae. Each strain of N. gonorrhoeae has multiple (10-11) genes encoding for Opas. Identifiable elements in opa genes include the coding repeat within the signal sequence, conserve 5' and 3' regions, and hypervariable regions (HV1 and HV2) located within the structural gene. N. gonorrhoeae strains appear to have many biological properties in common that are either HV-region-mediated or associated with the presence of specific HV regions, suggesting that HV regions could be found in many clinical isolates. Oligonucleotides from three source strains representing three conserved regions of opa, 12 HV1 regions, and 14 HV2 regions were used by dot blot analysis to probe 120 clinical isolates of N. gonorrhoeae. The probe for the coding repeat hybridized to all 120 strains, the 3' conserved-region probe reacted with 98% of the strains, and the 5' conserved-region probe with 90% of the strains. Nine HV1 probes hybridized to 3.3-39.2% of the strains, and 13 of the HV2 probes hybridized to 1.7-25% of the isolates. Analysis of the number of probes that hybridized to each of the isolates showed that 19% did not hybridize with any of the HV1 probes and 25% did not hybridize with any of the HV2 probes. Approximately three-quarters of the isolates hybridized with one, two or three of the HV1 probes or one, two or three of the HV2 probes; 89% of the isolates hybridized to least one HV1 or one HV2 probe. The data indicate that some genes encoding HV regions of N. gonorrhoeae Opa proteins are widely distributed in nature.     

Application of automated image analysis to demonstrate the correlation between ras p21 expression and severity of gliomas

We found a direct correlation between increasing ras p21 protein immunopositivity and severity of human glioma using computer-assisted, digital-image processing to quantify the amount of p21 immunoreactive to the monoclonal antibody RAP-5. We determined that there was a significant difference in reactivity between glioblastoma multiformes and more-differentiated astrocytomas (experiment-wise error less than 0.05). This result confirmed the conclusions made on the same tumors using standard light microscopy and visual examination. Immunohistochemistry quantized by automated image analysis may be a useful adjunct to current histopathological strategies since it decreases assay subjectivity and variation.     

Longevity factor in hominoid social organization

In most primate groups emigration of the maturing young of one or the other sex tends to serve as an incest avoidance mechanism. Among most primate species it is the males who change groups. This supports the theory that, in terms of reproductive success, males should compete for mates and females should compete for resources. In hominoids the combination of increased longevity and greater female discrimination in mate selection seems responsible for female emigration. This may relate to the high frequency of patrilocality and male control of resources among human groups.     

Wall-less prokaryotes from fall flowers in central United States and Maryland

Four spiroplasma strains and eleven isolates tentatively identified as acholeplasmas were obtained from fall flowers in Colorado, Nebraska, Illinois, and Maryland. Although the acholeplasma isolates were heterogeneous, all showed antigenic sharing with a group of unnamed organisms (L1 and related strains) isolated in othe studies from flowers in Florida. The W20 and W24 isolates from Nebraska were partially related to the L1 group by DNA-DNA homology and polyacrylamide gel electrophoresis (PAGE) analyses. A Colorado spiroplasma (W13) was identifed as a new strain of group IV complex. Three spiroplasma strains from flowers in Maryland old fields represent a new serovar with closest affinity to subgroup I-4 and to the LB12 and N525 serovars of group I. Widespread occurrence of acholeplasmas on flowers in this study, and on plant surfaces in general, suggests that, like spiroplasmas they probably will be found to reside in arthropods.     

Characterization of isolated Fe-loaded rat hepatocytes prepared by collagenase perfusion

Summary Hepatocytes from livers of rats loaded by Fe-dextran treatment were isolated by an in situ collagenase perfusion technique and evaluated for their biochemical, cytochemical, and morphological characteristics in cell culture. Iron loads 15 times higher than in normal rat liver cells isolated in the same way were retained in the preparations with 40% present as hemosiderin. A simple centrifugation-mathematical approach is described for the calculation of Fe content in the hepatocyte (95%) and reticuloendothelial (5%) fractions in the isolates. The cells were cultured for 22 h without loss of protein synthesis capability or significant changes in cell count, viability, endogenous glutamate-oxaloacetate transaminase (GOT) or Fe and were morphologically similar in most respects to unloaded (normal) hepatocytes similarly cultured. Studies are in progress to assess the utility of these preparations as a model for Fe mobilization from Fe-loaded animals. This work is supported by National Institutes of Health Grants AM 25647-03 (M. Dawson, Principal Investigator) and GM 28158-01 (C. Tyson, Principal Investigator). The technical assistance of Mr. Jack E. Dabbs, Mr. Charles Hart, and Mr. Randy Douglas is acknowledged.     

The baboon endogenous virus genome. II. Provirus sequence variations in baboon cell DNA.

Restriction analysis of the approximately 100 integrated baboon endogenous virus (BaEV) proviruses in baboon cells and tissues has revealed two major sequence variations, both in the gag gene region of the genome. One, a 150 nucleotide pair insert, is present in a small proportion of the proviral DNAs and some baboons, but is present in the majority of the proviral DNAs of other baboons. The second, a Bam HI recognition sequence located 2.25 kb from the proviral 5' end, is missing or modified in approximately one-half of the integrated genomes. We consider the possibility that accumulation of proviruses not containing the 0.15 kb insert is correlated with viral activation and expression since it is this form that is a replication intermediate in freshly infected permissive cells. It is evident from these initial studies that the organization of the multiple BaEV proviruses in baboon DNA has undergone modification during evolution.     

A sequence specific endonuclease from Micrococcus radiodurans

A new sequence specific endonuclease, MraI has been purified from Micrococcus radiodurans. This enzyme cleaves bacteriophage λ DNA at three sites, adenovirus type 2 DNA at more than 12 sites and has a unique site on ΦX174 DNA. It has no sites on SV40, PM2 and pBR322 DNA. The three sites on phage λ DNA are different from those cleaved by SmaI, XmaI and XorII. The sites of cleavage are located at 0.424, 0.447 and 0.834 fractional lengths on the physical map of λ DNA. MraI is shown to be an isoschizomer of SacII and SstII recognizing the palindromic nucleotide sequence ′5-CCGC↓GG-3′. The enzyme shows an absolute requirement of Mg²⁺, but is active in the absence of added 2-mercaptoethanol. The enzyme shows activity at a broad range of temperature and pH with an optimum at 45°C and pH 7.0. MraI represents the first restriction enzyme from a bacterium whose DNA lacks modified methylated bases.     

Morphogenetic effects of light and guanine derivatives on the fruiting myxobacterium Stigmatella aurantiaca.

When low cell densities of the myxobacterium Stigmatella aurantiaca were starved on an inorganic salts and agar medium, cell aggregation and fruiting body formation showed a striking dependency upon the presence of light. This dependency was not manifested when sufficient amounts of guanosine or guanine nucleotides were added to the medium. Light interacted cooperatively with suboptimal concentrations of guanine compounds to promote development. None of the other purine or pyrimidine derivatives, with the exception of adenine, stimulated development. However, aggregates that formed in the presence of adenine did not mature into fruiting bodies and instead disaggregated.