Labour: when to worry.

To ensure an optimum result in pregnancy it is essential that the physician be alert in the antenatal period to recognize those women and their babies who are at risk during labour. Premature labour, with its attendant risk of respiratory distress syndrome in the newborn, continues to be an important factor in perinatal morbidity and mortality. Early recognition of predisposing factors and the judicious use of myometrial inhibiting agents have helped to reduce the incidence of fetal prematurity in these cases. A long interval between rupture of the membranes and delivery continues to be a danger to both mother and fetus. Delivery is recommended when gestation is beyond 36 weeks or when there are signs of incipient infection, and once labour has begun antibiotics should be used prophylactically. Failure of labour to progress should be recognized and managed aggressively in its early stages. Amniotomy and oxytocin infusion have reduced considerably the incidence of prolonged labour and its risks to both mother and fetus. The role of intrapartum monitoring of the fetal heart rate, measurement of the pH in the fetus''s scalp blood and assessment of amniotic fluid is discussed, as is the monitoring of maternal well-being.     

Mitral regurgitation: when to intervene?

Although mitral regurgitation (MR) is the most common valvular heart disease, it should be regarded as a complex multifactorial disease that involves     

Sexual selection: when to expect trade-offs

Empirical evidence is mixed for interspecific trade-offs in investment among sexually selected traits. One important reason may be the way resources are allocated among species. Consider a set of species that obtains the same fitness pay-off for investment in song or plumage. Simulations where resources were normally distributed among species revealed significant trade-offs between song and plumage ( ± s.d. of r = −0.54 ± 0.06). However, simulations where resources were distributed in a negative binomial fashion usually produced positive correlations (r = 0.11 ± 0.09). Repeating simulations on three published studies that concomitantly quantified elaboration of song and plumage indicated that trade-offs are likely, although these analyses make assumptions that require further evaluation. Moreover, there are currently too few empirical distributions to make generalizations about the likelihood of interspecific trade-offs in sexually selected traits.     

Plant genetics: when not to interfere

New evidence suggests that the model plant Arabidopsis has two biochemically distinct pathways that produce genetic crossovers. Studies in several organisms have revealed that one kind of crossover regulation - crossover interference - is applied differently from species to species. Arabidopsis appears to use an interference system similar to that of budding yeast.     

bHLH proteins know when to make a stoma

In Arabidopsis thaliana, stomata develop through a stereotypical pattern of cell divisions. Three recent publications demonstrate that three bHLH proteins act successively in such lineages to drive the formation of stomata. SPEECHLES drives the division that initiates the stomatal-cell lineage. Then MUTE induces the formation of the immediate stomatal precursor cell. Finally, FAMA causes the stomatal precursor cell to divide into the two guard cells that surround each stomatal pore.     

Prokaryotic genes in eukaryotic genome sequences: when to infer horizontal gene transfer and when to suspect an actual microbe

Assessment of phylogenetic positions of predicted gene and protein sequences is a routine step in any genome project, useful for validating the species' taxonomic position and for evaluating hypotheses about genome evolution and function. Several recent eukaryotic genome projects have reported multiple gene sequences that were much more similar to homologues in bacteria than to any eukaryotic sequence. In the spirit of the times, horizontal gene transfer from bacteria to eukaryotes has been invoked in some of these cases. Here, we show, using comparative sequence analysis, that some of those bacteria‐like genes indeed appear likely to have been horizontally transferred from bacteria to eukaryotes. In other cases, however, the evidence strongly indicates that the eukaryotic DNA sequenced in the genome project contains a sample of non‐integrated DNA from the actual bacteria, possibly providing a window into the host microbiome. Recent literature suggests also that common reagents, kits and laboratory equipment may be systematically contaminated with bacterial DNA, which appears to be sampled by metagenome projects non‐specifically. We review several bioinformatic criteria that help to distinguish putative horizontal gene transfers from the admixture of genes from autonomously replicating bacteria in their hosts' genome databases or from the reagent contamination.