The spark of life

The sperm activates the egg to begin developing into an embryo by triggering a wave of intracellular calcium release, which sweeps across the egg like a forest fire. The identity of the signaling molecules that mediate this fundamental event has remained a mystery until recently. Now, new information emerging from the genome projects has made it possible to isolate and characterize the proteins responsible.     

Placental acquisition of maternal specific IgG and Helicobacter pylori colonization in infancy

Background. Colonization with Helicobacter pylori generally occurs in infancy, and the microorganism is often acquired from close family members. Rate of infant colonization may be affected by maternal immune status. Methods. To investigate the potential protective effect of anti‐H. pylori immunoglobulin G (IgG) acquired via the placenta, 65 mothers and their infants were studied from the infant's birth for 1 year. Circulating IgG antibodies were measured by enzyme‐linked immunosorbent assay (ELISA) in cord blood and every 8 weeks. Immunoblotting was performed on sera from infants with significant increases in IgG levels. Rate of infant H. pylori colonization was measured by ¹³C urea breath tests every 4 weeks from the age of 12 weeks. Results. Maternal and infant cord blood specific IgG levels were correlated (R² = .747, p < .001). Infant H. pylori specific IgG fell 5‐fold compared to maternal levels over the first 6 months of life, and rose subsequently in many cases, with the development of novel immunoblot patterns. There were no significant associations between the age at first positive urea breath test and maternal or infant cord specific H. pylori IgG levels. Conclusions. Transplacentally acquired specific IgG antibody does not protect infants from colonization by H. pylori.     

Cytoplasmic location of undermethylated messenger RNA in Novikoff cells.

Novikoff cells in culture were labeled with L-[methyl-3H]methionine and [U-14C]uridine in the presence of (a) TubHcy2, (b) AdoHcy, (c) homocysteine, (d) tubercidin, or (e) without any additions. Only in cultures labeled in the presence of TubHcy were undermethylated cap structures observed to represent a significant portion of [3H]methyl radioactivity. Novikoff cells in culture were then simultaneously labeled with L-[methyl-3H]methionine and [32P]orthophosphate in the presence or absence of TubHcy. Total cytoplasmic, polysomal and monosomal poly(A)-containing RNAs were analyzed. Both monosomal and polysomal mRNA fractions from TubHcy-treated cells contain partially methylated cap structures, suggesting that 2'-O-methylation of the nucleoside adjacent to the pyrophosphate linkage in caps is not required for transport, ribosomal binding or translation. Comparison of nuclear and cytoplasmic cap structures from normal and inhibited cultures indicate that an altered mRNA population is generated in the presence of TubHcy.     

Circular dichroism and NMR studies of metabolically stablealpha-methylpolyamines: spectral comparison with naturally occurring polyamines

Three synthetic polyamine analogs, alpha-methylspermine, and alpha,alpha'-dimethylspermine, were compared with their naturally occurring counterparts, spermidine and spermine, by two different spectral techniques. The interaction of polyamines with oligodeoxynucleotides was measured by circular dichroism in order to monitor the polyamine-induced conversion of right-handed B-DNA to the left-handed Z-form. The methylated analogs were shown to be equally effective as the natural polyamines in inducing the B --> Z transition. The pH dependence of the chemical shift of all carbon atoms in each of the five polyamines was measured by (13)C-NMR spectroscopy. With the exception of expected changes in chemical shift due to the presence of the alpha-methyl substituents, the chemical shifts and pH dependence of all carbon atoms in the three alpha-methyl polyamines were similar to the corresponding naturally occurring polyamines. The combined data indicate that alpha-methyl polyamines have physical properties that are very similar to their natural counterparts. The two metabolically stable polyamine analogs, alpha-methylspermidine and alpha,alpha'-dimethylspermine, are therefore useful surrogates for spermidine and spermine in the study of numerous polyamine-mediated effects in mammalian cell cultures and can be used in such studies without the requirement for coadministration of amine oxidase inhibitors.     

Masking repeats while clustering ESTs

A problem in EST clustering is the presence of repeat sequences. To avoid false matches, repeats have to be masked. This can be a time-consuming process, and it depends on available repeat libraries. We present a fast and effective method that aims to eliminate the problems repeats cause in the process of clustering. Unlike traditional methods, repeats are inferred directly from the EST data, we do not rely on any external library of known repeats. This makes the method especially suitable for analysing the ESTs from organisms without good repeat libraries. We demonstrate that the result is very similar to performing standard repeat masking before clustering.     

Volts and salts in pain relief

Many pharmaceutical companies are pursuing the 'holy grail' of an effective pain relief drug that has no harmful side effects. The voltage-gated sodium channel family offers some promising targets.     

Reproductive physiology of female tilapia broodstock

Tilapiine fish have become one of the mostcommercially important groups of cultured freshwaterfish with in excess of 850 000 tonnes producedannually in a range of countries (e.g. Thailand,Taiwan, China, Philippines, Belgium and the USA).However, poor broodstock productivity, owing to lowfecundity and asynchronous spawning cycles, remainsone of the most significant outstanding constraintsupon commercial tilapia production and its futureexpansion. This paper reviews current understanding ofthe reproductive physiology of tilapia with particularemphasis upon those factors deemed critical tosuccessful broodstock management. Special emphasis isplaced upon factors such as fecundity, egg size,spawning periodicity, ovarian development and theexogenous and endogenous regulatory mechanismsinvolved in their control. Mouthbrooding speciesexhibit higher levels of parental care but fecundityis lower and egg size larger than insubstrate-spawning species. Fecundity, the number ofeggs oviposited per spawning act, can be < 350 inmouthbrooders such as Oreochromis mossambicus(Peters) but can exceed 12 000 in substrate-spawnerssuch as Tilapia zillii (Gervais). Eggs producedby mouthbrooders normally exceed 2 mm in diameterwhilst those of substrate spawners average only 1.5 mm.Interspawning intervals of mouthbrooders generallyaverage 30–50 days whether the fish are held in natural orartificial conditions, although substrate-spawningspecies such as Tilapia zillii can re-spawnafter only 6 or 7 days. The dynamics of theasynchronous pattern of ovarian development adopted bytilapiines are complex and result in the ovary beingdominated by late-vitellogenic/maturing oocytes asearly as 8–10 days after spawning. Advancement ofour understanding of these key areas will be essentialif the present constraints on tilapia culture are tobe overcome.     

Serum concentration of total soluble CD44 is elevated in smokers

Soluble CD44 isoforms have been reported as markers of specific malignancies and inflammatory diseases. However, recent reports suggest tobacco smoking may lead to an elevation in the circulating concentration of specific CD44 variants. We, therefore, investigated the effect of smoking status on circulating levels of total sCD44. Total soluble CD44 was measured by enzyme-linked immunosorbent assay in the serum of two age- and gender-matched groups consisting of smokers (n = 19) and non-smokers (n = 20). Smoking status was confirmed by analysis of serum cotinine. The concentration of total sCD44 was found to be significantly elevated in smokers compared with non-smokers (p = 0.025). The observation that total sCD44 concentration is raised in smokers may have relevance to the aetiology of smoking-associated diseases. The effect of smoking on sCD44 concentrations should be considered when assessing the role of sCD44 as a marker of inflammatory disease, cancer, or other disease processes.