High level of divergence of male-reproductive-tract proteins, between Drosophila melanogaster and its sibling species, D. simulans

We compared male-reproductive-tract polypeptides of Drosophila melanogaster and D. simulans by using two-dimensional gel electrophoresis. Approximately 64% of male-reproductive-tract polypeptides were identical between two randomly chosen isofemale lines from these two species, compared with 83% identity for third-instar imaginal wing-disc polypeptides. Qualitatively similar differences were found between reproductive tracts and imaginal discs when D. sechellia was compared with D. melanogaster and with D. simulans. When genic polymorphism was taken into account, approximately 10% of male- reproductive-tract polypeptides were apparently fixed for different alleles between D. melanogaster and D. simulans; this proportion is the same as that found for soluble enzymes by one-dimensional gel electrophoresis. Strikingly, approximately 20% of male-reproductive- tract polypeptides of either D. melanogaster or D. simulans had no detectable homologue in the other species. We propose that proteins of the Drosophila male reproductive tract may have diverged more extensively between species than have other types of proteins and that much of this divergence may involve large changes in levels of polypeptide expression.      

Pre-induction priming of the uterine cervix with oral prostaglandin E2 and a placebo

A double blind study was undertaken to determine the effectiveness or oral prostaglandin E2 as a means of improving the pelvic score prior to induction of labour. 48 patients who were greater than 37 were gestation and who had Bishop scores of less than 6 entered the study. Ten tablets were given on an hourly regime. Of 25 patients in the prostaglandin group, 17 were considered successes (68.0%), whereas of 23 patients who received a placebo, 9 were successes (39.1%). No adverse effects were recorded. Prostaglandin E2 is therefore considered a safe and effective method for priming the unfavourable cervix prior to induction of labour.     

Monoclonal antibodies to rabbit liver cytochrome P-448

Cytochrome P-448 (mol wt 55,000 Daltons) from rabbit liver was purified to a specific content of 16.6 nmol/mg. Mice were immunised with this preparation, their spleens removed and dissociated lymphocytes hybridised with myeloma cells. Four monoclonal antibodies against cytochrome P-448 were raised and partially characterised. All four antibodies interacted with cytochrome P-448 in intact microsomal fractions and selectively immunoadsorbed cytochrome P-448 from solubilised microsomal preparations. One of the antibodies inhibited benzo[a] pyrene hydroxylase activity in a reconstituted system, one had no effect on activity and two increased activity. The possible applications of such antibodies are discussed.     

The DsbA signal sequence directs efficient, cotranslational export of passenger proteins to the Escherichia coli periplasm via the signal recognition particle pathway

The Escherichia coli cytoplasmic protein thioredoxin 1 can be efficiently exported to the periplasmic space by the signal sequence of the DsbA protein (DsbAss) but not by the signal sequence of alkaline phosphatase (PhoA) or maltose binding protein (MBP). Using mutations of the signal recognition particle (SRP) pathway, we found that DsbAss directs thioredoxin 1 to the SRP export pathway. When DsbAss is fused to MBP, MBP also is directed to the SRP pathway. We show directly that the DsbAss-promoted export of MBP is largely cotranslational, in contrast to the mode of MBP export when the native signal sequence is utilized. However, both the export of thioredoxin 1 by DsbAss and the export of DsbA itself are quite sensitive to even the slight inhibition of SecA. These results suggest that SecA may be essential for both the slow posttranslational pathway and the SRP-dependent cotranslational pathway. Finally, probably because of its rapid folding in the cytoplasm, thioredoxin provides, along with gene fusion approaches, a sensitive assay system for signal sequences that utilize the SRP pathway.     

Growth of <Emphasis Type="Italic">Helicobacter pylori</Emphasis> in a long spiral form does not alter expression of immunodominant proteins

Background  

We have previously reported that altered culture conditions (a broth media with shaking) could induce a strain of Helicobacter pylori to assume a long spiral morphology resembling that described for Helicobacter heilmannii. The present study was initiated to determine if other strains of H. pylori could be induced to assume that morphology and if doing so would alter the expression of immunodominant proteins.     

Similar hypotensive responses to resistance exercise with and without blood flow restriction

Low intensity resistance exercise (RE) with blood flow restriction (BFR) has gained attention in the literature due to the beneficial effects on functional and morphological variables, similar to those observed during traditional RE without BFR, while the effects of BFR on post-exercise hypotension remain unclear. The aim of the present study was to compare the blood pressure (BP) response of trained normotensive individuals to RE with and without BFR. In this cross-over randomized trial, eight male subjects (23.8 ± 4 years, 74 ± 3 kg, 174 ± 4 cm) completed two exercise protocols: traditional RE (3 x 10 repetitions at 70% one-repetition maximum [1-RM]) and low intensity RE (3 x 15 repetitions at 20% 1-RM) with BFR. Blood pressure measurements were performed after 15 min of seated rest (0), immediately after and 10 min, 20 min, 30 min, 40 min, 50 min and 60 min after the experimental sessions. Similar hypotensive effects for systolic BP (SBP) were observed for both protocols (P < 0.05) after exercise, with no differences between groups (P > 0.05) and no statistically significant difference for diastolic BP (P > 0.05). These results suggest that in normotensive trained individuals, both traditional RE and RE with BFR induce hypotension for SBP, which is important to prevent cardiovascular disturbances.     

Adelphocorisella Miyamoto and Yasunaga newly recorded from Australia, with the description of a new species (Heteroptera: Miridae: Mirinae)

Adelphocorisella australis sp. n. is described from north Queensland. This, the first representative of the genus known from Australia, is compared with the two previously described species, both from Japan.     

Polar Positioning of a Conjugation Protein from the Integrative and Conjugative Element ICEBs1 of Bacillus subtilis

ICEBs1 is an integrative and conjugative element found in the chromosome of Bacillus subtilis. ICEBs1 encodes functions needed for its excision and transfer to recipient cells. We found that the ICEBs1 gene conE (formerly yddE) is required for conjugation and that conjugative transfer of ICEBs1 requires a conserved ATPase motif of ConE. ConE belongs to the HerA/FtsK superfamily of ATPases, which includes the well-characterized proteins FtsK, SpoIIIE, VirB4, and VirD4. We found that a ConE-GFP (green fluorescent protein) fusion associated with the membrane predominantly at the cell poles in ICEBs1 donor cells. At least one ICEBs1 product likely interacts with ConE to target it to the membrane and cell poles, as ConE-GFP was dispersed throughout the cytoplasm in a strain lacking ICEBs1. We also visualized the subcellular location of ICEBs1. When integrated in the chromosome, ICEBs1 was located near midcell along the length of the cell, a position characteristic of that chromosomal region. Following excision, ICEBs1 was more frequently found near a cell pole. Excision of ICEBs1 also caused altered positioning of at least one component of the replisome. Taken together, our findings indicate that ConE is a critical component of the ICEBs1 conjugation machinery, that conjugative transfer of ICEBs1 from B. subtilis likely initiates at a donor cell pole, and that ICEBs1 affects the subcellular position of the replisome.Integrative and conjugative elements (also known as conjugative transposons) and conjugative plasmids are key elements in horizontal gene transfer and are capable of mediating their own transfer from donor to recipient cells. ICEBs1 is an integrative and conjugative element found in some Bacillus subtilis strains. Where found, ICEBs1 is integrated into the leucine tRNA gene trnS-leu2 (Fig. ​(Fig.1)1) (7, 14, 21).Open in a separate windowFIG. 1.Genetic map of ICEBs1. conE (formerly yddE), regulatory genes (gray arrows), and genes required for integration, excision, and nicking (hatched arrows) are indicated. The number of transmembrane (TM) segments for each protein predicted by cPSORTdb (46) is indicated below each gene. Other topology programs yield similar but not identical predictions.ICEBs1 gene expression, excision, and potential mating are induced by activation of RecA during the SOS response following DNA damage (7). In addition, ICEBs1 is induced by increased production or activation of the ICEBs1-encoded regulatory protein RapI. Production and activity of RapI are indicative of the presence of potential mating partners that do not contain a copy of ICEBs1 (7). Under inducing conditions, the ICEBs1 repressor ImmR (6) is inactivated by proteolytic cleavage mediated by the antirepressor and protease ImmA (12). Most ICEBs1 genes then become highly expressed (7). One of these genes (xis) encodes an excisionase, which in combination with the element''s integrase causes efficient excision and formation of a double-stranded circle (7, 38). The circular form is nicked at the origin of transfer, oriT, by a DNA relaxase, the product of nicK (39). Under appropriate conditions, ICEBs1 can then be transferred by mating into B. subtilis and other species, including the pathogens Listeria monocytogenes and Bacillus anthracis (7). Once transferred to a recipient, ICEBs1 can be stably integrated into the genome at its attachment site in trnS-leu2 by the ICEBs1-encoded integrase (38).In contrast to what is known about ICEBs1 genes and proteins involved in excision, integration, and gene regulation, less is known about the components that make up gram-positive organisms'' mating machinery, defined as the conjugation proteins involved in DNA transfer (18, 24). The well-characterized mating machinery of gram-negative organisms can serve as a preliminary model (15, 16, 37, 48). Gram-negative organisms'' mating machinery is a type IV secretion system composed of at least eight conserved proteins that span the cell envelope. For example, the conjugation apparatus of the Agrobacterium tumefaciens Ti plasmid (pTi) is composed of 11 proteins (VirB1 through VirB11), including the ATPase VirB4 (16). VirB4 family members interact with several components of their cognate secretion systems and may energize machine assembly and/or substrate transfer (16, 48). The secretion substrate is targeted to the conjugation machinery by a coupling protein. Coupling proteins, such as VirD4 of pTi, interact with a protein attached to the end of the DNA substrate and couple the substrate to other components of the conjugation machinery. Coupling proteins might also energize the translocation of DNA through the machinery. Both VirB4 and VirD4 belong to the large HerA/FtsK superfamily of ATPases (29). Two other characterized members of this superfamily are the chromosome-partitioning proteins FtsK and SpoIIIE (29), which are ATP-dependent DNA pumps (reviewed in reference 2).Some of the proteins encoded by the conjugative elements of gram-positive organisms are homologous to components of the conjugation machinery from gram-negative organisms (1, 9, 14, 29), indicating that some aspects of conjugative DNA transfer may be similar in gram-positive and gram-negative organisms. For example, ConE (formerly YddE) of ICEBs1 has sequence similarities to VirB4 (29). YdcQ may be the ICEBs1-encoded coupling protein, as it is phylogenetically related to other coupling proteins (29, 44). Despite some similarities, the cell envelopes and many of the genes encoding the conjugation machinery are different between gram-positive and gram-negative organisms, indicating that there are likely to be significant structural and mechanistic differences as well.To begin to define the conjugation machinery of ICEBs1 and to understand spatial aspects of conjugation, we examined the function and subcellular location of ConE of ICEBs1. Our results indicate that ConE is likely a crucial ATPase component of the ICEBs1 conjugation machinery. We found that ConE and excised ICEBs1 DNA were located at or near the cell poles. We propose that the conjugation machinery is likely located at the cell poles and that mating might occur from a donor cell pole.