First trimester prenatal diagnosis and detection of carriers of haemophilia A using the linked DNA probe DX13.

Although the use of a gene specific deoxyribonucleic acid (DNA) probe is the method of choice for detecting carriers of genes for rare genetic disorders, there will always be families in which such probes cannot be used because key subjects are not informative for restriction fragment length polymorphisms in or around the gene. In these cases closely linked DNA markers have to be used. An X chromosome specific DNA probe, DX13, which is closely linked to the haemophilia A locus on the X chromosome, was used for early prenatal diagnosis in two cases and to detect carriers in a series of nine possible heterozygote women. The first reported crossover between DX13 and the factor VIII:C locus was observed in this study. There are complexities inherent in using any linked DNA probe for assignment of genes, but such techniques are clinically important.     

Chronic ulceration of the leg: extent of the problem and provision of care.

A postal survey in two health board areas in Scotland, encompassing a population of about one million, identified 1477 patients with chronic ulcers of the leg. Women outnumbered men by a ratio of 2.8:1. The median age of the women was 74 and of the men 67. Seventy two (5%) were hospital inpatients, 174 (12%) were managed jointly by the primary care team and outpatient departments, and 1201 (83%) were managed entirely in the community. Efforts to improve the management of chronic ulcers of the leg should focus on primary health care.     

Growth and mortality of individual plants as a function of “available area”

Summary We looked at the relationship between available area, as defined by Thiessen polygons around individual plants, and plant size and mortality in even-aged green-house populations of Lapsana communis L. Polygon area was a good predictor of plant weight in these populations. After nine weeks growth, just prior to the onset of self-thinning, the dry weight of plants was directly proportional to the square root of polygon area. After the onset of selfthinning, plant weight appeared to be directly related to polygon area to the 3/2 power. Plants in small polygons were much more likely to die than those in larger areas. Thinning changed the frequency distribution of polygon sizes from highly skewed and unequal to normal and more equal, while inequality in surviving plant sizes did not appear to be affected by thinning.     

Impaired clearance of free cystine from lysosome-enriched granular fractions of I-cell-disease fibroblasts.

Cultured fibroblasts from patients with I-cell disease (mucolipidosis II) accumulate excessive amounts of free cystine, similarly to cells from patients with nephropathic cystinosis, a disorder of lysosomal cystine transport. To clarify whether the intralysosomal accumulation of cystine in I-cell-disease fibroblasts was due to a defective disposal mechanism, we measured the rates of clearance of free [35S]cystine from intact normal, cystinotic and I-cell-disease fibroblasts. Loss of radioactivity from the two mutant cell types occurred slowly (t 1/2 = 500 min) compared with the rapid loss from normal cells (t 1/2 = 40 min). Lysosome-rich granular fractions isolated from three different cystine-loaded normal, cystinotic and I-cell-disease fibroblast strains were similarly examined for non-radioactive cystine egress. Normal granular fractions lost cystine rapidly (mean t 1/2 = 43 min), whereas cystinotic granular fractions did not lose any cystine (mean t 1/2 = infinity). I-cell-disease granular fractions displayed prolonged half-times for cystine disposal (mean = 108 min), suggesting that I-cell-disease fibroblasts, like cystinotic cells, possess a defective carrier mechanism for cystine transport.     

Regional localisations and linkage relationships of seven RFLPs and myotonic dystrophy on chromosome 19

Summary We have studied the genetic linkage relationships of seven DNA polymorphisms on chromosome 19, with each other and with the myotonic dystrophy locus. The DNA sequences were localised to various regions of the chromosome using translocations in somatic cell hybrids. These results provide the basis for a linkage map of most of chromosome 19, and suggest that the myotonic dystrophy locus is close to the centromere.     

Dinitrogen fixation by obligate and facultative anaerobic bacteria in association with cellulolytic fungi

The anaerobic bacteriumClostridium butyricum is the major contributor to nitrogen gains by a cellulolytic/nitrogen-fixing population isolated from straw. Growth of the anaerobe is supported by the products of fungal cellulases. The facultative anaerobeEnterobacter cloacae does not make a significant direct contribution to nitrogen fixation but in association withC. butyricum allows the anaerobe to grow under aerobic conditions. The major function ofE. cloacae is though to be provision of oxygen-depleted microsites.     

Nitrate Reductases from Wild-Type and nr(1)-Mutant Soybean (Glycine max [L.] Merr.) Leaves : II. Partial Activity, Inhibitor, and Complementation Analyses

Soybean (Glycine max [L.] Merr.) leaves have been shown to contain three forms of nitrate reductase (NR). Two of the forms, which are present in leaves of wild-type (cv. Williams) plants grown in the absence of NO₃⁻, are termed constitutive and designated c₁NR and c₂NR. The third form, which is present in NO₃⁻-grown mutant (nr₁) plants lacking the constitutive forms, is termed inducible and designated iNR. Samples of c₁NR, c₂NR, and iNR obtained from appropriately treated plants were analyzed for the presence of partial activities, response to inhibitors, and ability to complement a barley NR which lacks the molybdenum cofactor (MoCo) but is otherwise active.

The three forms were similar to most assimilatory NR enzymes in that they (a) exhibited NADH-cytochrome c reductase, reduced flavin mononucleotide-NR, and reduced methyl viologen-NR partial activities; (b) were inhibited by p-hydroxymercuribenzoate at the site of initial electron transport through each enzyme; (c) were more inhibited by CN⁻ in their reduced enzyme state as compared with their oxidized state; and (d) complemented a MoCo-defective NR (e.g. contained cofactors with characteristics similar to the MoCo found in barley NR and commercial xanthine oxidase). However, among themselves, they showed dissimilarities in their response to treatment with HCO₃⁻ and CN⁻, and in their absolute ability to complement the barley NR. The site of effect for these treatments was the terminal cofactor-containing portion of each enzyme. This indicated that, although a terminal cofactor (presumably a MoCo) was present in each form, structural or conformational differences existed in the terminal cofactor-protein complex of each form.

     

Prostaglandin release by zygotes and endometria of pregnant rabbits

When 4-day rabbit zygotes were incubated for 1 h at 37 degrees C in vitro, very little prostaglandin (PG) was released into the medium, and the concentration of PGs in the zygotes after incubation was also low. The release of prostaglandin E (PGE) and prostaglandin F (PGF) into the medium, and their concentration in the zygotes after incubation, increased sharply on Days 6 and 7 of pregnancy, reaching, by Day 7, values close to 200 ng of each PG released in 1 h per mg of protein. By contrast, endometrial samples on Days 4 and 5 of pregnancy released more PGF and less PGE than the zygotes of the same ages on a per mg of protein basis, and on Days 6 and 7, less of both PGs. Furthermore, endometrial concentrations of PGs after incubation, except for PGF on Day 4, were always lower than values for zygotes. Endometrial concentrations of PGs on Day 6 were lower before than after incubation. Although there was a slight upward trend in PG release by endometrial samples with increasing length of pregnancy, the changes were minimal and, in the case of PGE, none of the mean values exceeded 1 ng per mg of protein. In 7-day blastocysts, high levels of both PGF and PGE were found in the blastocoelic fluid, and these did not change during the 1-h incubation. The release of PGF and PGE during in vitro incubation of ruptured and washed Day 6 blastocysts was stimulated by arachidonic acid, and that of PGF, but not PGE, inhibited by indomethacin. The release of PGE, but not of PGF, from Day 6 blastocysts was inhibited by low temperature, and the same conditions inhibited release of both PGF and PGE from endometrial cell suspensions. It seems that both blastocysts and endometria have capability to synthesize PGs, the blastocysts being particularly active in this regard on Days 6 and 7 of pregnancy. It is hypothesized that, in vivo, Day 6 and 7 blastocysts release large quantities of PGs which trigger some of the local endometrial changes associated with pregnancy.     

Linkage of the evolutionarily-related serum albumin and alpha-fetoprotein genes within q11-22 of human chromosome 4

Albumin and alpha-fetoprotein are structurally related serum proteins, having a similar gene structure and, conceivably, a common evolutionary origin. To test their relative arrangement in the human genome, the serum albumin and alpha-fetoprotein genes were mapped by in situ hybridization of cloned human albumin or alpha-fetoprotein cDNA to human mitotic chromosome preparations. Analysis of cells hybridized with the serum albumin probe showed that 39% of cells exhibited grains on the proximal portion of the long arm of chromosome 4 (bands q11-22), with these grains comprising 30% of all labeled sites throughout these mitoses. Similarly, in cells hybridized with the alpha-fetoprotein probe, 39% of cells were observed to contain silver grains on 4q11-22, these grains constituting 20% of all labeled sites in these cells. These results demonstrate chromosomal localization and linkage of the serum albumin and alpha-fetoprotein genes within bands q11-22 of the long arm of human chromosome 4.     

Chromosomal mapping of Xenopus 5S genes: somatic-type versus oocyte-type.

Xenopus 5S RNA genes exhibit a pattern of differential expression during development in which some members (oocyte-type) are transcribed only in oocytes, while others (somatic-type) are expressed in both oocytes and somatic cells. Using cloned DNA probes specific for each gene type, we determined the positions of these genes on Xenopus metaphase chromosomes by in situ hybridization. Somatic-type 5S genes in both X. laevis and X. borealis are located at the distal end of the long arm of only one chromosome (number 9). The oocyte-type 5S RNA genes are found at the distal ends of the long arms of most Xenopus chromosomes, including chromosome 9. Thus, large scale differences in chromosomal location cannot explain the selective expression of these genes, as suggested previously.