Molecular cloning, sequence and expression of Aa-polB , a mitochondrial gene encoding a family B DNA polymerase from the edible basidiomycete Agrocybe aegerita

An ORF of 1716 nucleotides, putatively encoding a DNA polymerase, was characterized in the mitochondrial genome of the edible basidiomycete Agrocybe aegerita. The complete gene, named Aa-polB, and its flanking regions were cloned and sequenced from three overlapping restriction fragments. Aa-polB is located between the SSU rDNA (5′ region) and a gene for tRNA^Asn (3′ region), and is separated from these genes by two A+T-rich intergenic regions of 1048 (5′ region) and 3864 (3′ region) nucleotides, which lack repeated sequences of mitochondrial or plasmid origin. The deduced Aa-POLB protein shows extensive sequence similarity with the family B DNA polymerases encoded by genomes that rely on protein-primed replication (invertrons). The domains involved in the 3′→5′ exonuclease (Exo I to III) and polymerase (Pol I to Pol V) activities were localized on the basis of conserved sequence motifs. The alignment of the Aa-POLB protein (571 amino acids) with sequences of family B DNA polymerases from invertrons revealed that in Aa-POLB the N-terminal region preceding Exo I is short, suggesting a close relationship with the DNA polymerases of bacteriophages that have linear DNA. The Aa-polB gene was shown to be present in all wild strains examined, which were collected from a wide range of locations in Europe. As shown by RT-PCR, the Aa-polB gene is transcribed in the mitochondria, at a low but significant level. The likelihood of the coexistence of Aa-POLB and Pol γ in the A. aegerita mitochondrion is discussed in the light of recent reports showing the conservation of the nucleus-encoded Pol γ from yeast to human. Received: 13 October 1998 / Accepted: 21 December 1998     

Characterisation of a novel homodimeric N-acetyl-beta-D-glucosaminidase from Streptococcus gordonii

An N-acetyl-beta-D-glucosaminidase (GcnA) from Streptococcus gordonii FSS2 was cloned and sequenced. GcnA had a deduced molecular mass of 72,120 Da. The molecular weight after gel-filtration chromatography was 140,000 Da and by SDS-PAGE was 70,000 Da, indicating that the native protein was a homodimer. The deduced amino acid sequence had significant homology to a glycosyl hydrolase from Streptococcus pneumoniae and the conserved catalytic domain of the Family 20 glycosyl hydrolases. GcnA catalysed the hydrolysis of the synthetic substrates, 4-methylumbelliferyl (4MU)-N-acetyl-beta-D-glucosaminide, 4MU-N-acetyl-beta-D-galactosaminide, 4-MU-beta-D-N,N'-diacetylchitobioside, and 4-MU-beta-D-N,N',N'-chitotrioside as well as the respective chito-oligosaccharides. GcnA was optimally active at pH 6.6 and 42 degrees C. The Km for 4-MU-beta-D-N,N',N'-chitotrioside, 45 microM, was the lowest for all the substrates tested. Hg2+, Cu2+, Fe2+, and Zn2+ completely inhibited while Co2+, Mn2+, and Ni2+ partially inhibited activity. S. gordonii FSS2 and a GcnA negative mutant grew equally well on chito-oligosaccharides as substrates. The S. gordonii sequencing projects indicate two further N-acetyl-beta-D-glucosaminidase activities.     

Familial early onset macular degeneration in cynomolgus monkeys (Macaca fascicularis)

The mode of inheritance of macular degeneration was determined with 45 cynomolgus monkeys (18 females and 27 males) who were the offspring of one breeding male with typical macular degeneration. In the first generation, 27 offspring (10 females and 17 males) were born from mating between the macular degeneration-affected founder male and 5 normal female breeders. Among them, 18 monkeys (9 females and 9 males) were judged as having macular degeneration (affected). Next, the distribution of affected offspring was examined with 18 offspring who were born from 3 different mating pairs, normal vs normal, affected vs normal and affected vs affected, when they became 2 years old. All of the 9 monkeys (4 females and 5 males) obtained from the 2 pairs of normal vs normal were normal. On the other hand, 6 affected monkeys (3 females and 3 males) were detected in 8 offspring from the mating pair of affected vs normal, and the single offspring produced by the mating pair of affected vs affected was affected. These results showed that this degeneration must be early onset familial macular degeneration controlled by autosomal dominant gene(s).     

Expression profiles of the novel human connexin genes hCx30.2, hCx40.1, and hCx62 differ from their putative mouse orthologues

In this study we show by Northern blot hybridization that the novel human (h) connexin (Cx) genes hCx25, hCx30.2, hCx31.9, hCx40.1, hCx59, and hCx62 are transcribed in different adult tissues. The hCx25 RNA is slightly expressed in placenta, and hCx59 and hCx62 RNA are both transcribed in skeletal muscle, although the latter is also slightly expressed in heart. Expression profiles of three orthologous human (h) and mouse (m) connexin gene pairs, i.e., hCx30.2 versus mCx29, hCx40.1 versus mCx39, and hCx62 versus mCx57, differ strongly, in contrast to other orthologous connexins with higher sequence identities. Thus, several of the new human connexin genes appear to have evolved to different expression patterns and presumably to different functions compared to their orthologues in the mouse genome. (121)     

Intergenerational transmission of fertility in Spain among cohorts born during the first half of twentieth century

It is known that historically fertility is correlated between generations of the same family. These links tend to be explained either in terms of the biogenetic determinants of reproduction or by the transmission of intra-familial values associated with reproduction and family life. Less is known about the micro-determinants of these links or about the extent to which the progressive modernization of reproductive outcomes over the past century has affected behavior. In this paper, we will address these issues for Spain with data from the Socio-Demographic Survey (SDS) carried out in 1991 and including data on cohorts born between 1900 and 1946. These data enable us to explore the micro determinants of fertility at different points of time during this period. Our results point to the existence of a significant correlation between intergenerational reproductive outcomes that persists and strengthens throughout this period of demographic change. Results confirm the importance of birth order in large family groups where firstborn offspring are more likely to have larger families than subsequent siblings. There is also evidence that the strength of these intergenerational ties increases with the onset of more modern demographic behavior characterized by sharply declining fertility. The results presented here promise to condition future debates on the subject.     

Grandmothering in Cambridgeshire, 1770–1861

The effects of grandparent survival on child survival and mean interbirth interval, both independent of and relative to parent survival, were investigated in a historical population. Families for the data set were reconstituted from the parish and census records of Cambridgeshire, 1770–1861. In a logistic regression analysis, only the mother’s and the maternal grandmother’s survival were found to be significant predictors of child survival. Maternal grandmother’s survival was found to influence child survival both via maternal survival and independent of maternal survival. Grandparent survival was not found to influence mean interbirth interval. These findings are reviewed with respect to other studies of grandmothering, the Grandmother Hypothesis, and the evolutionary significance of human female postreproductive lifespan. Gillian Ragsdale is a postgraduate student at the Leverhulme Centre for Human Evolution Studies (LCHES), Cambridge University, UK, currently investigating the evolution of human social cognition. She was originally a molecular geneticist, and subsisted through the intervening years in educational publishing.     

NDRG1 interacts with APO A-I and A-II and is a functional candidate for the HDL-C QTL on 8q24

Hereditary Motor and Sensory Neuropathy Lom (HMSNL) is a severe autosomal recessive peripheral neuropathy, the most common form of demyelinating Charcot-Marie-Tooth (CMT) disease in the Roma (Gypsy) population. The mutated gene, N-myc downstream-regulated gene 1 (NDRG1), is widely expressed and has been implicated in a range of processes and pathways. To gain an insight into NDRG1 function we performed yeast two-hybrid screening and identified interacting proteins whose known functions suggest involvement in cellular trafficking. Further analyses, focusing on apolipoproteins A-I and A-II, confirmed their interaction with NDRG1 in mammalian cells and suggest a defect in Schwann cell lipid trafficking as a major pathogenetic mechanism in HMSNL. At the same time, the chromosomal location of NDRG1 coincides with a reported HDL-C QTL in humans and in mice. A putative role of NDRG1 in the general mechanisms of HDL-mediated cholesterol transport was supported by biochemical studies of blood lipids, which revealed an association between the Gypsy founder mutation, R148X, and decreased HDL-C levels.     

Estimation of individual genetic effects from binary observations on relatives applied to a family history of respiratory illnesses and chronic lung disease of newborns

This paper considers methods for estimating the relationship between a binary response Y and the genetic effects responsible for a second binary trait Z. The responses Y are observed only for target individuals, and the responses Z are observed only for the relatives of these targets. The analysis consists of two parts. The first part concerns the analysis of the family data Z and the second part estimates the relation between the genetic effects and Y. For the family data, a generalized linear mixed model with a logit link and Gaussian genetic (random) effects is used. Estimates of the variances of the genetic effects are obtained by using a pseudo-profile log-likelihood method. Estimation of the log likelihood involves averaging over n-dimensional normal distributions, which is done by importance sampling. The methods used in the second part are straightforward. The methods are applied to a data set containing chronic lung disease (CLDN) responses of newborns and asthma (AS), allergy (AL), chronic bronchitis (CB) and eczema (EC) responses observed for the relatives of these newborns. The clinical question is whether genetic effects of AS, AL, CB, and EC have an effect on the risk for CLDN. It can be concluded that for AS, AL, CB, and EC, the influence of genetic effects is significant. However, these genetic predispositions have no significant effect on CLDN.