Microbial communities colonising nutrient-enriched marine sediment

Sediment cores were set up to study microbial colonisation and interactions on marine sand grains under enrichment conditions. Cores were enriched with photosynthetic media in the light and dark (PL, PD) and heterotrophic media in the light and dark (HL, HD), and were incubated for 25 days. Sediment chlorophylls were then measured by acetone extraction, viable heterotrophic bacteria by plate counts, and numbers of cells mm^–2 sand grain surface by s.e.m. Chlorophyll a occurred in all sediments but was highest in the PL sediment. Bacteriochlorophyll a was only observed in the HL sediment. Heterotrophic viable counts were high in the HL and HD sediments. Dense growth of diatoms and blue-green algae, and a marine fungal Thraustochytrid sp. occurred on PL grains. The blue-green alga Schizothrix was often associated with the diatom Amphora on PL grains. Many different bacteria grew on HL and HD grains and some unusual colony and cell morphologies were recorded (Caulobacter, Flexibacter, polymer strands). Characteristic flakey material sometimes occurred in hollows on grains. The results are discussed in relation to microbial communities in low energy sedimentary environments.     

Relative Embryo Growth Rates in the Annual Cicer L. Species

Early embryo growth rates were studied in the nine annual speciesof Cicer L., namely, C. arietinum L., C. bijugum Rech., C. chorassanicum(Bge.) M. Pop., C. cuneatum Rich., C. echinospermum Dav., C.judaicum Boiss, C. pinnatifidum J. and S., C. reticulatum Lad.and C. yamashitae Kit. The number of embryo cells increasedexponentially with time and was log linear in all the species.Species differed in their mean cell doubling time (MCDT). Cicerechinospermum and C. yamashitae had, respectively, the longestand the shortest MCDT which ranged from 9.67 to 16.15 h forthe nine species. Failure of successful interspecific hybridizationbetween C. arietinum and the wild annual species was only partlyexplained by differences in MCDT of the parental species. Relativegenetic closeness still plays the major role in determiningsuccess of interspecific hybridization in Cicer. Chickpea, Cicer, embryo, interspecific hybridization, suspensor     

Size-hierarchy in a year-class and "condition" of common minnow Esomus danricus (Ham.) in relation to various ecological factors operating in the pond environment

Investigations were made on the existence of size-hierarchy in specimens of Esomus danricus (Ham.) belonging to the same year-class, and the variations in condition factor of the different size-groups. Divergence in the growth rates of individual fish resulted in the development of size-hierarchy in the population. Marked changes seemed to occur in condition factor of the different size-groups. A multitude of factors operating simultaneously in the pond environment appeared to govern the condition factor of fish.     

Molecular evidence for two vitellogenin genes and processing of vitellogenins in the American cockroach, Periplaneta americana

The American cockroach, Periplaneta americana has two vitellins (Vn1 and Vn2) and corresponding vitellogenins (Vg1 and Vg2). Vns/Vgs were separated on the SDS-PAGE as three major polypeptide bands [170, 100 (multisubunits), and 50 kD] and a minor polypeptide band (150 kD) both in the egg (mature terminal oocyte) extract and in the female hemolymph. We previously cloned one Vg (Vg1) cDNA and showed that the 170-kD polypeptide originated from the C-terminus of the Vg1. In the present study, we cloned the other Vg (Vg2) cDNA. It is 5,826 bp long encoding 1,876 amino acid residues (including 16 residues for putative signal peptide) in a single ORF. The deduced amino acid sequences of both Vgs (Vg1 and Vg2) of P. americana showed 30% identity. The GL/ICG motif is followed by eight cysteine residues at conserved locations near the C-terminal and the DGXR motif starts 18 residues upstream of the GL/ICG motif. The chemically determined N-terminal amino acid sequences of the 150-kD and of the 50-kD polypeptides matched exactly with each other and with the deduced N-terminal amino acid sequence of the Vg2 cDNA. The pattern of processing in P. americana Vns/Vgs is discussed.     

Parental Age Affects Somatic Mutation Rates in the Progeny of Flowering Plants

In humans, it is well known that the parental reproductive age has a strong influence on mutations transmitted to their progeny. Meiotic nondisjunction is known to increase in older mothers, and base substitutions tend to go up with paternal reproductive age. Hence, it is clear that the germinal mutation rates are a function of both maternal and paternal ages in humans. In contrast, it is unknown whether the parental reproductive age has an effect on somatic mutation rates in the progeny, because these are rare and difficult to detect. To address this question, we took advantage of the plant model system Arabidopsis (Arabidopsis thaliana), where mutation detector lines allow for an easy quantitation of somatic mutations, to test the effect of parental age on somatic mutation rates in the progeny. Although we found no significant effect of parental age on base substitutions, we found that frameshift mutations and transposition events increased in the progeny of older parents, an effect that is stronger through the maternal line. In contrast, intrachromosomal recombination events in the progeny decrease with the age of the parents in a parent-of-origin-dependent manner. Our results clearly show that parental reproductive age affects somatic mutation rates in the progeny and, thus, that some form of age-dependent information, which affects the frequency of double-strand breaks and possibly other processes involved in maintaining genome integrity, is transmitted through the gametes.In humans, it has long been recognized that the reproductive age of the parents has an influence on the health of their progeny. An older reproductive age of the mother is known to increase the fraction of aneuploid gamete formation (Hurles, 2012). For instance, the risk for a trisomy increases from 2% to 3% for mothers in their 20s to more than 30% for mothers in their 40s (Hassold and Hunt, 2009). The age of the father also has an effect on the frequency of spontaneous congenital disorders and common complex diseases, such as autism and some cancers (Goriely and Wilkie, 2012). Indeed, sperm from 36- to 57-year-old men have more double-strand breaks (DSBs) than those of 20- to 35-year-old individuals (Singh et al., 2003). Similarly, the efficiency of DSB repair was reported to decrease with age in vegetative tissues of the plant model system Arabidopsis (Arabidopsis thaliana; Boyko et al., 2006).Owing to the continuous divisions of spermatogonial stem cells, the male germline of humans is thought to be more mutagenic than the female germline. Indeed, it was shown that the paternal germline is more mutagenic than the maternal one with respect to base substitutions (Kong et al., 2012) and replication slippage errors at microsatellites (Sun et al., 2012). It is also known that carriers of germline mutations in mismatch repair (MMR) genes in humans are prone to get colorectal cancer and that the risk depends on the parent-of-origin of the mutation (van Vliet et al., 2011). The molecular basis of these parental effects is not entirely clear but is likely to involve higher rates of nondisjunction during female meiosis, higher mutation rates during spermatogenesis, and probably additional effects of aging.In contrast to the effect of parental age on germline mutations, not much is known about potential effects of parental reproductive age on somatic mutation rates in the offspring. However, it has been shown in animal studies that radiation of males can lead to somatic mutations in their progeny—and subsequent generations—that cannot be attributed to mutations in the paternal germline (for review, see Little et al., 2013). Moreover, several recent studies have illustrated the existence of complex parental and transgenerational effects in humans, although their molecular basis is not clear (Grossniklaus et al., 2013). These effects can be of either genetic nature (but the effect is seen even in offspring that did not inherit the genetic variant from their parents; for review, see Nadeau, 2009) or epigenetic nature (where environmental influences can possibly exert effects on subsequent generations; for review, see Pembrey et al., 2006; Pembrey, 2010; Curley et al., 2011). It is currently not known whether such parental effects affect the somatic mutation rates in the offspring or whether the effects are modulated by parental age.Taking advantage of the plant model system Arabidopsis, in which various somatic mutation rates can readily be assessed (Bashir et al., 2014), we investigated the effects of parental reproductive age on somatic mutation rates in the progeny. We report that there is a pronounced effect of parental age on somatic mutation rates in their offspring in a parent-of-origin-dependent fashion. Thus, some form of parental information, which is inherited through the gametes to the next generation, seems to alter the somatic mutation rates in the progeny and changes with parental reproductive age.