The interaction of 1-anilino-8-naphthalenesulfonate with thyroid lipids and membranes: A nuclear magnetic resonance study

The proton magnetic resonance (PMR) spectra of thyroid cell membranes and their total lipid extracts, in the presence of 1-anilino-8-naphthalenesulfonate (ANS), have been studied. The addition of ANS causes a shifting of the head group PMR signal, a splitting of the signal into two components and an increase in total spectral intensity. The data suggest that ANS interacts with phospholipid in the membrane as it does in total lipid vesicles. Evidence is also presented for the removal of lipids from the membrane, by ANS, and the subsequent formation of micelles. The membrane results are compatred with our earlier work on the interaction of ANS with egg phosphatidycholine (P.C.) vesicles and the results are used in explaining the inhibition of iodide transport in isolated thyroid slices.     

Expression of cDNAs encoding wild-type and mutant neuromodulins in Escherichia coli: comparison with the native protein from bovine brain

Murine cDNA that encodes neuromodulin, a neurospecific calmodulin binding protein, was inserted into the plasmid pKK223-3 for expression in Escherichia coli. After being transformed into E. coli strain SG20252 (lon-), the expression vector directed the synthesis of a protein that was recognized by polyclonal antibodies raised against bovine neuromodulin. The recombinant protein expressed in E. coli was found to be tightly associated with insoluble cell material and was extractable only with guanidine hydrochloride or sodium dodecyl sulfate. Following solubilization with guanidine hydrochloride, the protein was purified to apparent homogeneity by a single CaM-Sepharose affinity column step with a yield of 0.2 mg of protein/L of E. coli culture. The availability of the purified recombinant neuromodulin made it possible to answer several specific questions concerning the structure and function of the protein. Despite the fact that murine neuromodulin is 12 amino acid residues shorter than the bovine protein and the recombinant protein expressed in E. coli may lack any posttranslational modifications, the two proteins displayed similar biochemical properties in almost all respects examined. They both had higher affinity for CaM-Sepharose in the absence of Ca2+ than in its presence; they were both phosphorylated in vitro by protein kinase C in a Ca2+- and phospholipid-dependent manner; neither form of the proteins was autophosphorylated, and the phosphorylated form of the proteins did not bind calmodulin. The recombinant neuromodulin and neuromodulin purified from bovine brain had similar, but not identical, affinities of calmodulin, indicating that the palmitylation of the protein that occurs in animal cells is not crucial for calmodulin interactions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of the surface microlayer on nutrients,chlorophyll and algal diversity of a small eutrophic bog pond

Nutrients, chlorophyll, phaeophytin and algal abundances were investigated in the surface microlayer and at subsurface depths in a small eutrophic bog pond. Nutrient levels were consistently higher in the microlayer while algal abundance was sometimes higher but sometimes lower in the microlayer than at near subsurface depths. Algal diversity values were strongly influenced by the depth of flagellate blooms, and in contrast to previous studies, diversity in the microlayer was higher than at near subsurface depths. These results are discussed in terms of weather parameters, affinity of algal species for the surface and differences between microlayer ecology in shallow and deep water systems.     

Social stimulation and the resumption of copulation in Rhesus (Macaca mulatto) and stumptail (Macaca arctoides) Macaques

Copulatory data derived from observations of social groups of rhesus and stumptail macaques were analyzed to test the hypothesis that pairs of animals would resume copulation significantly sooner if a second male copulated with the female shortly after the first male’s ejaculation. Data from both groups supported the hypothesis. These results, extending previous studies in Macaca nemestrina,suggest that the shortening of copulatory intervals by social stimuli occurs in several species, both in social groups and in experimentally created triads. These findings also are consistent with the hypothesis that socially mediated resumption of mating is related to intrasexual competition among males.     

Carbon isotope fractionation by ribulose-1,5-bisophosphate carboxylase from various organisms

Carbon isotope fractionation by structurally and catalytically distinct ribulose-1,5-bisphosphate carboxylases from one eucaryotic and four procaryotic organisms has been measured under nitrogen. The average fractionation for 40 experiments was −34.1 ‰ with respect to the δ¹³C of the dissolved CO₂ used, although average fractionations for each enzyme varied slightly: spinach carboxylase, −36.5 ‰; Hydrogenomonas eutropha, −38.7 ‰; Agmenellum quadruplicatum, −32.2 ‰; Rhodospirillum rubrum, −32.1 ‰; Rhodopseudomonas sphaeroides peak I carboxylase, −31.4 ‰; and R. sphaeroides peak II carboxylase, −28.3 ‰. The carbon isotope fractionation value was largely independent of method of enzyme preparation, purity, or reaction temperature, but in the case of spinach ribulose-1,5-bisphosphate carboxylase fractionation, changing the metal cofactor used for enzyme activation had a distinct effect on the fractionation value. The fractionation value of −36.5 ‰ with Mg²⁺ as activator shifted to −29.9 ‰ with Ni²⁺ as activator and to −41.7 ‰ with Mn²⁺ as activator. These dramatic metal effects on carbon isotope fractionation may be useful in examining the catalytic site of the enzyme.     

Effect of phenethylbiguanide on sugar and amino acid transport in rabbit ileum

Phenethylbiguanide has been shown to be an inhibitor of sugar and amino acid uptake in both $\text{in vivo}$ and $\text{in vitro}$ conditions. This action could be due to a competition for sodium sites on the sugar and amino acid carrier molecules. The effects of phenethylbiguanide on $\text{in vitro}$ intestinal preparations indicate that this compound has a time-dependent effect, it is most effective when placed on the mucosal surface but is also effective on the serosal surface. Furthermore, competition studies indicate that it is a competitive inhibitor of sugar uptake and a non-competitive inhibitor of amino acid uptake. These results are consistent with the differences in the mechanism of coupled transport between sugars and amino acids, but, do not substantiate the idea that phenethylbiguanide competes for the sodium site on the ternary carrier.     

Young,intact and nested retrotransposons are abundant in the onion and asparagus genomes

Background and Aims

Although monocotyledonous plants comprise one of the two major groups of angiosperms and include >65 000 species, comprehensive genome analysis has been focused mainly on the Poaceae (grass) family. Due to this bias, most of the conclusions that have been drawn for monocot genome evolution are based on grasses. It is not known whether these conclusions apply to many other monocots.

Methods

To extend our understanding of genome evolution in the monocots, Asparagales genomic sequence data were acquired and the structural properties of asparagus and onion genomes were analysed. Specifically, several available onion and asparagus bacterial artificial chromosomes (BACs) with contig sizes >35 kb were annotated and analysed, with a particular focus on the characterization of long terminal repeat (LTR) retrotransposons.

Key Results

The results reveal that LTR retrotransposons are the major components of the onion and garden asparagus genomes. These elements are mostly intact (i.e. with two LTRs), have mainly inserted within the past 6 million years and are piled up into nested structures. Analysis of shotgun genomic sequence data and the observation of two copies for some transposable elements (TEs) in annotated BACs indicates that some families have become particularly abundant, as high as 4–5 % (asparagus) or 3–4 % (onion) of the genome for the most abundant families, as also seen in large grass genomes such as wheat and maize.

Conclusions

Although previous annotations of contiguous genomic sequences have suggested that LTR retrotransposons were highly fragmented in these two Asparagales genomes, the results presented here show that this was largely due to the methodology used. In contrast, this current work indicates an ensemble of genomic features similar to those observed in the Poaceae.     

Evaluation of Cervical Cancer Screening Programs in C?te d’Ivoire,Guyana, and Tanzania: Effect of HIV Status

Background

HIV infection increases a woman’s risk for cervical cancer, and cervical cancer incidence and mortality rates are higher in countries with high HIV prevalence and limited resources for screening. Visual inspection with acetic acid (VIA) allows screening and treatment of cervical lesions in a single-visit approach (SVA), but data on its performance in HIV-infected women are limited. This study’s objective was to examine cervical cancer screening using VIA/SVA in programs serving HIV-infected women.

Methods

A VIA/SVA program with cryotherapy for VIA-positive lesions was implemented in Côte d’Ivoire, Guyana, and Tanzania from 2009 to 2012. The effect of HIV status on VIA positivity and on presence of cryotherapy-eligible lesions was examined using a cross-sectional study design, with Chi-square tests for comparisons and constructed multivariate logistic regression models. A P-value of < 0.05 was significant.

Findings

VIA was performed on 34,921 women, 10% (3,580) were VIA positive; 2,508 (85%) eligible women received cryotherapy during the same visit; only 234 (52%) of those who postponed returned for treatment; 622 (17%) VIA-positive women had lesions too large to be treated with cryotherapy and were referred for excisional treatment. In multivariate analysis—controlling for HIV status, location of the screening clinic, facility location, facility type, and country—compared to HIV-uninfected/unknown women, HIV-infected women had higher odds of being VIA positive (OR 1.95, 95% CI 1.76, 2.16, P<0.0001) and of having large lesions requiring referral (OR 1.93, 95% CI 1.49, 2.51, P< 0.0001). Minor treatment complications occurred in 19 of 3,032 (0.63%) women; none required further intervention.

Conclusions

This study found that compared to HIV-uninfected/unknown women, HIV-infected women had nearly twice the odds of being VIA-positive and to require referral for large lesions. SVA was safe and resulted in significant reductions in loss to follow-up. There is increased need for excisional treatment in countries with high HIV prevalence.     

Hybridization and barriers to gene flow in an island bird radiation

While reinforcement may play a role in all major modes of speciation, relatively little is known about the timescale over which species hybridize without evolving complete reproductive isolation. Birds have high potential for hybridization, and islands provide simple settings for uncovering speciation and hybridization patterns. Here we develop a phylogenetic hypothesis for a phenotypically diverse radiation of finch-like weaver-birds (Foudia) endemic to the western Indian Ocean islands. We find that unlike Darwin's finches, each island-endemic Foudia population is a monophyletic entity for which speciation can be considered complete. In explaining the only exceptions-mismatches between taxonomy, mitochondrial, and nuclear data-phylogenetic and coalescent methods support introgressive hybridization rather than incomplete lineage sorting. Human introductions of known timing of one island-endemic species, to all surrounding archipelagos provide two fortuitous experiments; (1) population sampling at known times in recent evolutionary history, (2) bringing allopatric lineages of an island radiation into secondary contact. Our results put a minimum time bound on introgression (235 years), and support hybridization between species in natural close contact (parapatry), but not between those in natural allopatry brought into contact by human introduction. Time in allopatry, rather than in sympatry, appears key in the reproductive isolation of Foudia species.