Y-chromosomal STR haplotypes in Berber and Arabic-speaking populations from Morocco

Twelve Y-chromosomal short tandem repeats (STRs), DYS19, DYS385, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS388, DYS426 and DYS439 were typed in Berber-speaking (n=49) and Arabic-speaking (n=60) population samples from Morocco.

Seasonal variations of aerosol residence time in the lower atmospheric boundary layer

During a one year period, from Jan. 2002 up to Dec. 2002, approximately 130 air samples were analyzed to determine the atmospheric air activity concentrations of short- and long-lived (222Rn) decay products 214Pb and 210Pb. The samples were taken by using a single-filter technique and gamma-spectrometry was applied to determine the activity concentrations. A seasonal fluctuation in the concentration of 214Pb and 210Pb in surface air was observed. The activity concentrations of both radionuclides were observed to be relatively higher during the winter/autumn season than in spring/summer season. The mean activity concentration of 214Pb and 210Pb within the whole year was found to be 1.4+/-0.27 Bq m(-3) and 1.2+/-0.15 mBq m(-3), respectively. Different 210Pb:214Pb activity ratios during the year varied between 1.78 x 10(-4) and 1.6 x 10(-3) with a mean value of 8.9 x 10(-4) +/- 7.6 x 10(-5). From the ratio between the activity concentrations of the radon decay products 214Pb and 210Pb a mean residence time (MRT) of aerosol particles in the atmosphere of about 10.5+/-0.91 d could be estimated. The seasonal variation pattern shows relatively higher values of MRT in spring/summer season than in winter/autumn season. The MRT data together with relative humidity (RH), air temperature (T) and wind speed (WS), were used for a comprehensive regression analysis of its seasonal variation in the atmospheric air.

Chromosomal mapping of Brassica oleracea based on ESTs from Arabidopsis thaliana: complexity of the comparative map

Expressed sequence tags (ESTs) from the Arabidopsis thaliana sequencing project were used to construct a genetic RFLP map for Brassica oleracea. Of the 110 A. thaliana ESTs tested, 95 were found to be informative RFLP probes in map construction. In total, 212 new loci corresponding to the 95 ESTs were added to the existing genetic map of B. oleracea. The enriched map covers all nine basic linkage groups and confirms that the chromosomes of B. oleracea and A. thaliana are similar in linear organization. However, varying levels of sequence conservation between the chromosomes of B. oleracea and A. thaliana were detected in different regions of the genomes. Long conserved regions encompassing entire chromosome arms in both genomes were identified; these are probably shared by descent. On the other hand, extensive rearrangements were observed in numerous chromosome regions, producing a mosaic of A. thaliana-like segments in the genome of Brassica. The presence of extensive chromosome duplication in A. thaliana was taken into consideration in the construction of the comparative maps of B. oleracea and A. thaliana.

Y-chromosome analysis in Egypt suggests a genetic regional continuity in Northeastern Africa

The geographic location of Egypt, at the interface between North Africa, the Middle East, and southern Europe, prompted us to investigate the genetic diversity of this population and its relationship with neighboring populations. To assess the extent to which the modern Egyptian population reflects this intermediate geographic position, ten Unique Event Polymorphisms (UEPs), mapping to the nonrecombining portion of the Y chromosome, have been typed in 164 Y chromosomes from three North African populations. The analysis of these binary markers, which define 11 Y-chromosome lineages, were used to determine the haplogroup frequencies in Egyptians, Moroccan Arabs, and Moroccan Berbers and thereby define the Y-chromosome background in these regions. Pairwise comparisons with a set of 15 different populations from neighboring European, North African, and Middle Eastern populations and geographic analysis showed the absence of any significant genetic barrier in the eastern part of the Mediterranean area, suggesting that genetic variation and gene flow in this area follow the "isolation-by-distance" model. These results are in sharp contrast with the observation of a strong north-south genetic barrier in the western Mediterranean basin, defined by the Gibraltar Strait. Thus, the Y-chromosome gene pool in the modern Egyptian population reflects a mixture of European, Middle Eastern, and African characteristics, highlighting the importance of ancient and recent migration waves, followed by gene flow, in the region.

The organization of cytoplasmic ribosomal protein genes in the Arabidopsis genome

Eukaryotic ribosomes are made of two components, four ribosomal RNAs, and approximately 80 ribosomal proteins (r-proteins). The exact number of r-proteins and r-protein genes in higher plants is not known. The strong conservation in eukaryotic r-protein primary sequence allowed us to use the well-characterized rat (Rattus norvegicus) r-protein set to identify orthologues on the five haploid chromosomes of Arabidopsis. By use of the numerous expressed sequence tag (EST) accessions and the complete genomic sequence of this species, we identified 249 genes (including some pseudogenes) corresponding to 80 (32 small subunit and 48 large subunit) cytoplasmic r-protein types. None of the r-protein genes are single copy and most are encoded by three or four expressed genes, indicative of the internal duplication of the Arabidopsis genome. The r-proteins are distributed throughout the genome. Inspection of genes in the vicinity of r-protein gene family members confirms extensive duplications of large chromosome fragments and sheds light on the evolutionary history of the Arabidopsis genome. Examination of large duplicated regions indicated that a significant fraction of the r-protein genes have been either lost from one of the duplicated fragments or inserted after the initial duplication event. Only 52 r-protein genes lack a matching EST accession, and 19 of these contain incomplete open reading frames, confirming that most genes are expressed. Assessment of cognate EST numbers suggests that r-protein gene family members are differentially expressed.

The organization of cytoplasmic ribosomal protein genes in the Arabidopsis genome

Eukaryotic ribosomes are made of two components, four ribosomal RNAs, and approximately 80 ribosomal proteins (r-proteins). The exact number of r-proteins and r-protein genes in higher plants is not known. The strong conservation in eukaryotic r-protein primary sequence allowed us to use the well-characterized rat (Rattus norvegicus) r-protein set to identify orthologues on the five haploid chromosomes of Arabidopsis. By use of the numerous expressed sequence tag (EST) accessions and the complete genomic sequence of this species, we identified 249 genes (including some pseudogenes) corresponding to 80 (32 small subunit and 48 large subunit) cytoplasmic r-protein types. None of the r-protein genes are single copy and most are encoded by three or four expressed genes, indicative of the internal duplication of the Arabidopsis genome. The r-proteins are distributed throughout the genome. Inspection of genes in the vicinity of r-protein gene family members confirms extensive duplications of large chromosome fragments and sheds light on the evolutionary history of the Arabidopsis genome. Examination of large duplicated regions indicated that a significant fraction of the r-protein genes have been either lost from one of the duplicated fragments or inserted after the initial duplication event. Only 52 r-protein genes lack a matching EST accession, and 19 of these contain incomplete open reading frames, confirming that most genes are expressed. Assessment of cognate EST numbers suggests that r-protein gene family members are differentially expressed.

The organization of cytoplasmic ribosomal protein genes in the Arabidopsis genome

Eukaryotic ribosomes are made of two components, four ribosomal RNAs, and approximately 80 ribosomal proteins (r-proteins). The exact number of r-proteins and r-protein genes in higher plants is not known. The strong conservation in eukaryotic r-protein primary sequence allowed us to use the well-characterized rat (Rattus norvegicus) r-protein set to identify orthologues on the five haploid chromosomes of Arabidopsis. By use of the numerous expressed sequence tag (EST) accessions and the complete genomic sequence of this species, we identified 249 genes (including some pseudogenes) corresponding to 80 (32 small subunit and 48 large subunit) cytoplasmic r-protein types. None of the r-protein genes are single copy and most are encoded by three or four expressed genes, indicative of the internal duplication of the Arabidopsis genome. The r-proteins are distributed throughout the genome. Inspection of genes in the vicinity of r-protein gene family members confirms extensive duplications of large chromosome fragments and sheds light on the evolutionary history of the Arabidopsis genome. Examination of large duplicated regions indicated that a significant fraction of the r-protein genes have been either lost from one of the duplicated fragments or inserted after the initial duplication event. Only 52 r-protein genes lack a matching EST accession, and 19 of these contain incomplete open reading frames, confirming that most genes are expressed. Assessment of cognate EST numbers suggests that r-protein gene family members are differentially expressed.

Genomic analysis of the Hsp70 superfamily in Arabidopsis thaliana

The Arabidopsis genome contains at least 18 genes encoding members of the 70-kilodalton heat shock protein (Hsp70) family, 14 in the DnaK subfamily and 4 in the Hsp110/SSE subfamily. While the Hsp70s are highly conserved, a phylogenetic analysis including all members of this family in Arabidopsis and in yeast indicates the homology of Hsp70s in the subgroups, such as those predicted to localize in the same subcellular compartment and those similar to the mammalian Hsp110 and Grp170. Gene structure and genome organization suggest duplication in the origin of some genes. The Arabidopsis hsp70s exhibit distinct expression profiles; representative genes of the subgroups are expressed at relatively high levels during specific developmental stages and under thermal stress.

Extensive duplication and reshuffling in the Arabidopsis genome

Systematic analysis of the Arabidopsis genome provides a basis for detailed studies of genome structure and evolution. Members of multigene families were mapped, and random sequence alignment was used to identify regions of extended similarity in the Arabidopsis genome. Detailed analysis showed that the number, order, and orientation of genes were conserved over large regions of the genome, revealing extensive duplication covering the majority of the known genomic sequence. Fine mapping analysis showed much rearrangement, resulting in a patchwork of duplicated regions that indicated deletion, insertion, tandem duplication, inversion, and reciprocal translocation. The implications of these observations for evolution of the Arabidopsis genome as well as their usefulness for analysis and annotation of the genomic sequence and in comparative genomics are discussed.

The distribution of T-DNA in the genomes of transgenic Arabidopsis and rice

Almost all the nuclear genes of four Gramineae (maize, wheat, barley, rice) and pea are located in DNA fractions covering only a 1-2% GC range and representing between 10 and 25% of the different genomes. These DNA fractions comprise large gene-rich regions (collectively called the 'gene space') separated by vast gene-empty, repeated sequences. In contrast, in Arabidopsis thaliana, genes are distributed in DNA fractions covering an 8% GC range and representing 85% of the genome. Here, we investigated the integration of a transferred DNA (T-DNA) in the genomes of Arabidopsis and rice and found different patterns of integration, which are correlated with the different gene distributions. While T-DNA integrates essentially everywhere in the Arabidopsis genome, integration was detected only in the gene space, namely in the gene-rich, transcriptionally active, regions of the rice genome. The implications of these results for the integration of foreign DNA are discussed.

The gene distribution in the genomes of pea, tomato and date palm

The vast majority of genes of maize, rice, barley and wheat are contained in long gene-rich regions (collectively called the 'gene space') separated by long gene-empty regions. The gene space covers a narrow, 0.8-1.6%, GC range, possibly because of the presence of abundant transposons. Here we report that the gene space is not an exclusive property of Gramineae, because it also exists in the large genome of pea (5000 Mb). Moreover, the gene space is not just dependent upon genome size, since a gene space is found in rice (415 Mb), but not in Arabidopsis (120 Mb), nor in two other plants investigated in the present work, date palm (250 Mb) and tomato (1000 Mb).

Distribution of genes in the genome of Arabidopsis thaliana and its implications for the genome organization of plants

Previous work has shown that, in the large genomes of three Gramineae [rice, maize, and barley: 415, 2,500, and 5,300 megabases (Mb), respectively] most genes are clustered in long DNA segments (collectively called the "gene space") that represent a small fraction (12-24%) of nuclear DNA, cover a very narrow (0.8-1.6%) GC range, and are separated by vast expanses of gene-empty sequences. In the present work, we have analyzed the small (ca. 120 Mb) nuclear genome of Arabidopsis thaliana and shown that its organization is drastically different from that of the genomes of Gramineae. Indeed, (i) genes are distributed over about 85% of the main band of DNA in CsCl and cover an 8% GC range; (ii) ORFs are fairly evenly distributed in long (>50 kb) sequences from GenBank that amount to about 10 Mb; and (iii) the GC levels of protein-coding sequences (and of their third codon positions) are correlated with the GC levels of their flanking sequences. The different pattern of gene distribution of Arabidopsis compared with Gramineae appears to be because the genomes of the latter comprise (i) many large gene-empty regions separating gene clusters and (ii) abundant transposons in the intergenic sequences of gene clusters. Both sequences are absent or very scarce in the Arabidopsis genome. These observations provide a comparative view of angiosperm genome organization.

Cdk2 activity is dispensable for the onset of DNA replication during the first mitotic cycles of the sea urchin early embryo

Earlier work reported the important role of Cdk2 as a regulator of DNA replication in somatic cells and in Xenopus extracts. In the present report we analyze in vivo the involvement of Cdk2 in DNA replication during early embryogenesis using the first mitotic cycles of sea urchin embryos. Unfertilized Sphaerechinus granularis eggs are arrested after the second meiotic cytokinesis. Fertilization resumes the block and induces DNA replication after a short lag period, making sea urchin early embryo a good model for studying in vivo the onset of DNA replication. We show that Cdk2 as well as its potential partner cyclin A are present in the nucleus in G1 and S phase and therefore available for DNA replication. In accordance with data obtained in Xenopus egg extracts we observed that Cdk2 kinase activity is low and stable during the entire cycle. However, in contrast with this in vitro system in which Cdk2 activity is required for the onset of DNA replication, the specific inhibition of Cdk2 kinase by microinjection of the catalytically inactive Cdk2-K33R or the inhibitor p21(Cip1) does not prevent DNA replication. Because olomoucine, DMAP, and emetine treatments did not preclude DNA synthesis, neither cyclin A/Cdk1 nor cyclin B/Cdk1 kinase activities are necessary to replace the absence of Cdk2 kinase in promoting DNA replication. These data suggest that during early embryogenesis Cdks activities, in particular Cdk2, are dispensable in vivo for the initiation step of DNA replication. However, the specific localization of Cdk2 in the nucleus from the beginning of M phase to the end of S phase suggests its involvement in other mechanisms regulating DNA replication such as inhibition of DNA re-replication and/or that its regulating role is achieved through a pathway independent of the kinase activity. We further demonstrate that even after inhibition of Cdk activities, the permeabilization of the nuclear membrane is required to allow a second round of DNA replication. However, in contrast to Xenopus egg extracts, re-replication can take place in the absence of DMAP-sensitive kinase.

Characterization of a new BLM mutation associated with a topoisomerase II alpha defect in a patient with Bloom's syndrome

Bloom's syndrome (BS), a human recessive disorder associated with an increased risk of malignancy, arises through mutations in both alleles of the BLM gene, which was recently identified as a member of the RecQ helicase family. BS cells are characterized by an increased rate of sister chromatid exchange (SCE). However, a subpopulation of lymphocytes exhibiting a normal level of SCE is observed in some patients. It has been proposed that reversion to a low-SCE phenotype involves an intragenic crossing over between the paternal and maternal BLM alleles, generating a wild-type allele. In this study we characterize a new BLM mutation in a BS patient leading to the replacement, in the C-terminal region of Blm, of a highly conserved cysteine by a phenylalanine in codon 1036. Moreover, our data show that this patient also inherited a BLM allele carrying a mutation affecting its expression and that a somatic intragenic crossing over was involved in reversion to the low-SCE phenotype. Further, we show that both topoisomerase II alpha mRNA and protein levels are decreased in the high-SCE cells derived from this patient, whereas they are normal in the corresponding low-SCE cells. Altogether, our data led us to propose that besides its putative helicase activity, Blm could be involved in transcription regulation.

The distribution of genes in the genomes of Gramineae

Recent investigations showed that most maize genes are present in compositional fractions of nuclear DNA that cover only a 1-2% GC (molar fraction of guanosine plus cytosine in DNA) range and represent only 10-20% of the genome. These fractions, which correspond to compositional genome compartments that are distributed on all chromosomes, were collectively called the "gene space." Outside the gene space, the maize genome appears to contain no genes, except for some zein genes and for ribosomal genes. Here, we investigated the distribution of genes in the genomes of two other Gramineae, rice and barley, and used a new set of probes to study further the gene distribution of maize. We found that the distribution of genes in these three genomes is basically similar in that all genes, except for ribosomal genes and some storage protein genes, were located in gene spaces that (i) cover GC ranges of 0.8%, 1.0%, and 1.6% and represent 12%, 17%, and 24% of the genomes of barley, maize, and rice, respectively; (ii) are due to a remarkably uniform base composition in the sequences surrounding the genes, which are now known to consist mainly of transposons; (iii) have sizes approximately proportional to genome sizes, suggesting that expansion-contraction phenomena proceed in parallel in the gene space and in the gene-empty regions of the genome; and (iv) only hybridize on the gene spaces (and not on the other DNA fractions) of other Gramineae.

The gene distribution of the maize genome

Previous investigations from our laboratory showed that the genomes of plants, like those of vertebrates, are mosaics of isochores, i.e., of very long DNA segments that are compositionally homogeneous and that can be subdivided into a small number of families characterized by different GC levels (GC is the mole fraction of guanine+cytosine). Compositional DNA fractions corresponding to different isochore families were used to investigate, by hybridization with appropriate probes, the gene distribution in vertebrate genomes. Here we report such a study on the genome of a plant, maize. The gene distribution that we found is most striking, in that almost all genes are present in isochores covering an extremely narrow (1-2%) GC range and only representing 10-20% of the genome. This gene distribution, which seems to characterize other Gramineae as well, is remarkably different from the gene distribution previously found in vertebrate genomes.

Active cyclin B-cdc2 kinase does not inhibit DNA replication and cannot drive prematurely fertilized sea urchin eggs into mitosis

Feedback mechanisms preventing M phase occurrence before S phase completion are assumed to depend on inhibition of cyclin B-cdc2 kinase activation by unreplicated DNA. In sea urchin, fertilization stimulates protein synthesis and releases eggs from G1 arrest. We found that in the one-cell sea urchin embryo cyclin B-cdc2 kinase undergoes partial activation before S phase, reaching in S phase a level that is sufficient for G2-M phase transition. S phase entry is not inhibited by this level of cyclin B-dependent kinase activity. Inhibition of DNA replication by aphidicolin suppresses nuclear envelope breakdown, yet it does not prevent the microtubule array from being converted from its interphasic to its mitotic state. Moreover, mitotic cytoplasmic events occur at the same time in control and aphidicolin-treated embryos. Thus unreplicated DNA only prevents mitotic nuclear, not cytoplasmic, events from occurring prematurely. These results together show that the inhibition of cyclin B-cdc2 kinase activation is probably not the only mechanism that prevents mitotic nuclear events from occurring as long as DNA replication has not been completed. In contrast, cytoplasmic mitotic events seem to be controlled by a timing mechanism independent of DNA replication, set up at fertilization, that prevents premature opening of a window for mitotic events.

Genetic heterogeneity of Pseudomonas aeruginosa clinical isolates revealed by esterase electrophoretic polymorphism and restriction fragment length polymorphism of the ribosomal RNA gene region

The intra-species differentiation of Pseudomonas aeruginosa was analysed by comparing the polymorphism of esterases by conventional polyacrylamide-agarose gel electrophoresis, the physicochemical properties of the variants of the major esterase P3 and the restriction fragment length polymorphism of ribosomal RNA gene regions (ribotyping) to O-serotyping for several panels of strains selected from among a series of 257 clinical isolates and two references strains, (ATCC nos. 10145 and 27853). The electrophoretic variation of four main kinds of esterase (P1-P4) and 11 additional esterases distinguished by their spectra of hydrolytic activity with synthetic substrates and by their sensitivity to di-isopropylfluorophosphate, allowed the discrimination of 67 zymotypes. Thirty-two esterase P3 variants were characterized by their pI, electrophoretic mobilities and titration curve analyses. They were distributed into two groups which, by these molecular criteria, seem to be distantly related. Combination of the patterns resulting from HindIII, EcoRI and BclI restriction endonuclease digestions allowed the discrimination of 33 ribotypes among 134 strains. The strains exhibiting esterase P3 variants of group 2 presented a distinct ribotype and belonged to serotype (O)12. They could constitute a distinct group within the species. For the majority of the strains, the absence of correlation between zymotype, ribotype and serotype argues for a high level of heterogeneity within P. aeruginosa and indicates that the parallel use of the first two methods represent a potential tool for epidemiological study.

Calcitonin gene-related peptide and islet amyloid polypeptide stimulate insulin secretion in RINm5F cells through a common receptor coupled to a generation of cAMP

The question as to whether the homologous peptides CGRP and IAPP can regulate insulin secretion in RINm5F cells was addressed. Chicken CGRP displayed a reproducible inhibitory effect on insulin secretion within 0.1 and 1 nM concentrations and a stimulatory effect at higher concentrations. The maximal stimulatory effects on insulin secretion were obtained with 1.0 microM of chicken CGRP (cCGRP), human alpha-CGRP (h alpha-CGRP) and human IAPP (hIAPP) which caused 246 +/- 22, 302 +/- 63 and 224 +/- 14 percent increases of control levels, respectively (p < 0.001). Similarly, maximal accumulations of cAMP were obtained with 1.0 microM of cCGRP, h alpha-CGRP and hIAPP with the respective percent increases of control levels of 587 +/- 24, 436 +/- 41 and 410 +/- 25 (p < 0.005). Thus the stimulatory effects on insulin secretion in RINm5F cells by cCGRP, h alpha-CGRP and hIAPP appear to be mediated by the cAMP pathway. Chicken CGRP, the most potent peptide tested, displayed a correlated dose response stimulation of intracellular cAMP and insulin release within the concentration range of 10-1000nM. The EC50 values of cCGRP for cAMP accumulation and insulin release were similar (20nM and 10nM respectively). The stimulatory effect of IAPP on cAMP was not additive with that of cCGRP suggesting that IAPP action was mediated by CGRP receptors. This hypothesis was further sustained by a preferential inhibition of 125I[His]h alpha-CGRP binding to RINm5F cells by cCGRP as compared to IAPP. We conclude that CGRP and IAPP, through a direct action on a chicken CGRP preferring receptor present in beta cells, stimulated insulin by a cAMP mediated pathway.

Characterization of specific calcitonin gene-related peptide receptors present in hamster pancreatic beta cells

Calcitonin gene-related peptide (CGRP) shares about 46% and 20% amino acid sequence homology with islet amyloid polypeptide (IAPP) and salmon calcitonin (sCT). We investigated whether these related peptides could cross-react with the specific binding of 125I-[His]hCGRP I to the CGRP receptor in hamster insulinoma cell membranes. A rapid dissociation of membrane bound 125I-[His]hCGRP I could be induced in the presence of 1 microM chicken CGRP (cCGRP). The specific 125I-[His]hCGRP I binding was inhibited by the related peptides and their half-maximal inhibitory concentrations (IC50) were: cCGRP (0.1 nM), rat CGRP I and human CGRP I and II (1.0-2.0 nM), fragment of hCGRP I (8-37) (150 nM), human IAPP (440 nM). The non-amidated form of hIAPP; human diabetes-associated peptide (hDAP) did not inhibit the binding of 125I-[His]hCGRP I and sCT was only effective at a high concentration (1 microM). Binding of 125I-[His]hCGRP I was dose dependently inhibited by guanosine-5'-O-(3-thiotriphosphate) or (GTP gamma S) and a 70% reduction of binding was obtained with 0.1 mM GTP gamma S. The IC50 value of cCGRP (0.1 nM) was increased 100-fold in the presence of 0.1 mM GTP gamma S. Human CGRP I and cCGRP at 2.5 microM did not stimulate the activity of hamster insulinoma cell membranes adenylate cyclase, while glucagon (1 microM) induced a 2-fold increase. Thus, specific CGRP receptors present in hamster beta cells are associated with G protein (s) and IAPP can interact with these receptors. These results and the observation that cCGRP and hCGRP I did not influence adenylate cyclase activity provide further evidence for CGRP receptor subtypes.

Processing of vasoactive intestinal peptide and transferrin in human cancerous colonic cells

Endocytosis of vasoactive intestinal peptide (VIP) and of transferrin (Tf) was comparatively studied in human cancerous colonic HT-29 cells. Cellular depletion in potassium inhibits the internalization of VIP (23%) and to a greater extent (42%) that of Tf. This indicates that clathrin-coated pits are also involved, at least in part, in VIP uptake. The distribution of 125I-Tf- or 125I-VIP-containing vesicles in sucrose gradients revealed low and high density vesicle subpopulations. The low density vesicle subpopulation represented a transient compartment from which incoming vesicles containing N-leucyl-beta naphthylamidase were recycled back to the membrane while those containing beta-hexosaminidase (HA) and ligand were mostly transferred into the high density compartment. Subsequent fusion of the latter with heavy vesicles was demonstrated by the shift of HA and ligand with vesicles that had been prelabeled with horseradish peroxidase (HRP). Simultaneous internalization of Tf-HRP and 125I-VIP showed that both the low and high density vesicle subpopulations comprised of two types of VIP-containing vesicle, as confirmed by the density shift reaction: two-thirds of VIP shifted with the Tf-HRP-containing vesicles to denser fractions and the remaining was found with unshifted vesicles. These findings indicate that the VIP-receptor complex processing in HT-29 cells follows two routes, the major route being common with Tf endocytosis.

Characteristics of maternal employment during pregnancy: effects on low birthweight

BACKGROUND

Although maternal employment is considered a risk factor for low birthweight (LBW), the manner in which employment might affect birthweight is poorly understood. In this analysis, selected characteristics of employment during pregnancy were examined for effects on pregnancy outcomes.

METHODS

Work characteristics included the number of hours per week, physical activities, and environmental conditions. The outcomes of interest were fetal growth retardation (less than 2500 grams at term) and preterm delivery (less than 37 weeks). The study population consisted of 2711 non-Black, married mothers who participated in the 1980 National Natality Survey (NNS). The NNS data were merged with data from the 1977 revision of The Dictionary of Occupational Titles (DOT) from which measures of occupational physical activities and environmental exposures were obtained. Logistic regression was used in the analysis.

RESULTS

Those who worked 40 or more hours per week were more likely than women who worked fewer hours to have a low birthweight delivery at greater than or equal to 37 weeks. No physical or environmental characterics of work were associated with low birthweight or preterm delivery.

CONCLUSIONS

Non-Black married American women may face a risk of delivering low-birthweight babies at or near term only if they work 40 or more hours each week. However, the lack of risk associated with other characteristics of work may be a function of measurement error in the DOT data source or of low levels of exposure in the analysis population.

Structure of rabbit butyrylcholinesterase gene deduced from genomic clones and from cDNA with introns

1. Three clones were isolated from a rabbit genomic library. They covered the entire coding sequence of the rabbit BChE gene. The positions of splice sites between exons 2, 3, and 4 are identical to those found in the human gene (Arpagaus et al., 1990). Exon 2 covers 83% of the coding sequence. This contrasts with the small size of exon 3 (167 bp) and large size of introns 2 and 3 (greater than 20 kb each). The active-site serine at position 198 is found in a highly conserved region. Aspartic acids in positions 91 and 170 are conserved in human and rabbit, and one of them could be involved in the calytic triad. Aspartic acid 70, present in the anionic site of human BChE, is also conserved in rabbit BChE. The coding sequences of human and rabbit BChE are 89% identical over 744 bp around the active-site serine. 2. In addition to the genomic clones, one cDNA clone (BNY1) was isolated. This cDNA was unusual in that it contained intronic sequences. The insert of 1 kb contained 167 coding bases homologous to the nucleotide sequence 1434 to 1600 of human cDNA and corresponded to exon 3 of the BChE gene. On each side of this coding region, consensus sequences of intron-exon boundaries were found. 3. The presence of large-size transcripts in Northern blots and the existence of a cDNA copy of unprocessed mRNA found in the BNY1 clone suggest a slow processing of transcripts. A genomic sequence unspliced in a cDNA of Torpedo AChE could give a transmembrane domain (Sikorav et al., 1988); the corresponding sequence in rabbit BChE gene, also found in a cDNA, had no homology with Torpedo AChE but could be translated in a hydrophobic C-terminal domain if maintained in mature mRNA.

Keratinophilic fungi and other moulds associated with air-dust particles from Egypt

One-hundred and eleven species and three species varieties belonging to 39 genera were collected from 50 dust samples on the five media used at 28 degrees C. Using the hair-baiting technique with horse hair, 10 species of Chrysosporium were isolated: C. asperatum, C. state of Arthroderma tuberculatum, C. indicum, C. inops, C. keratinophilum, C. merdarium, C. pannorum, C. queenslandicum, C. tropicum and C. xerophilum. True dermatophytes were isolated: Trichophyton verrucosum and Trichophyton sp. Also, numerous fungi tolerating high levels of cycloheximide were encountered, such as members of Acremonium, Aspergillus and Penicillium. On plates of glucose or cellulose Czapek-Dox agar (free from sucrose) the most frequent fungi were: Alternaria alternata, Aspergillus flavus, A. flavus var. columnaris, A. fumigatus, A. niger, A. ochraceus, A. sydowii, A. terreus, Chaetomium globosum, Cladosporium herbarum, Emericella nidulans, Fusarium oxysporum, Mucor hiemalis, Penicillium chrysogenum, P. oxalicum, Scopulariopsis brevicaulis and Ulocladium atrum. On plates of 50% sucrose or 10 and 20% NaCl-Czapek's agar, some interesting species were frequently encountered: Eurotium amstelodami, E. chevalieri, E. halophilicum, E. montevidensis, E. repens, E. rubrum and Scopulariopsis halophilica. The isolated fungi have been tested for osmophilicity and halophilicity, they showed different rates of growth on sucrose and sodium chloride-Czapek's medium of various osmotic potential.

Rift Valley fever in Egypt 1986. Surveillance of sheep flocks grazing in the northeast Nile Delta

From October 1985 through November 1986, 1714 presumably unvaccinated sheep in 13 nomadic flocks located in four provinces in Dakahliya Governorate, in the northeast Nile Delta, were ear tagged and monitored for acquisition of Rift Valley fever virus (RVFV) antibodies. Sheep were bled at approximately 3 month intervals and sera were tested for haemagglutination inhibition (HI) antibodies to RVFV. HI reactors were tested for RVFV specific IgM antibody by enzyme-linked immunosorbent assay (ELISA) and neutralizing antibody to RVFV by plaque reduction neutralization (PRN) tests. Base line results showed 1.2% prevalence of HI antibody to RVFV with titres from 1:20 to 1:320. All HI positive sera were PRN positive through PRN titres were generally higher than HI titres. No RVFV specific IgM antibody was detected in the HI and PRN positive sera. Throughout the study, no initially seronegative sheep became positive and no HI positive sheep showed an appreciable increase above initial antibody titre. These data indicate absence of RVFV transmission to sheep in Dakahliya Governorate during the period of the study.

Fructose-1,6-diphosphatase deficiency: diagnosis using leukocytes and detection of heterozygotes with radiochemical and spectrophotometric methods

The first two cases of fructose-1,6-diphosphatase (FDPase) deficiency from the Middle East have been diagnosed on leukocytes using a spectrophotometric assay and a new radiochemical technique. The control mean for FDPase measured by the spectrophotometric assay was 178.2 nm mg-1 h-1 (n = 12), 66.8 nm mg-1 h-1 for obligate heterozygotes (n = 4) and non-detectable in the two patients. By the radiochemical assay the values were controls, 103.3; heterozygotes, 20.6; patients, 0.46 and 3.5 nm mg-1 h-1. Using both methods it was possible to identify two certain FDPase heterozygotes and three non-carriers in the family of one of the probands. The radiochemical method was found to be more effective in differentiating heterozygotes from controls than the spectrophotometric method. However, either technique may be conveniently used for the diagnosis of FDPase deficiency in leukocytes.