The 8p-syndrome

A partial de novo deletion of 8p in a 10 1/2 month-old boy is described, the karyotype being 46,XY,del(8) (p21.3-qter:). Reduced birth weight, growth and psychomotor retardation, craniofacial dysmorphism with microcephaly and low set, deformed ears, stubby nose, wide set nipples, congenital heart defect and undescended testes were the main clinical findings. Death occurred at 2 1/2 years of age due to fulminant tracheo-bronchitis. Red cell glutathion reductase activity was normal. A review of previous cases with similar deletions outlines a definite clinical entity.     

Unusual chromatin in human telomeres.

We report that human telomeres have an unusual chromatin structure characterized by diffuse micrococcal nuclease patterns. The altered chromatin manifested itself only in human telomeres that are relatively short (2 to 7 kb). In contrast, human and mouse telomeres with telomeric repeat arrays of 14 to 150 kb displayed a more canonical chromatin structure with extensive arrays of tightly packed nucleosomes. All telomeric nucleosomes showed a shorter repeat size than bulk nucleosomes, and telomeric mononucleosomal particles were found to be hypersensitive to micrococcal nuclease. However, telomeric nucleosomes were similar to bulk nucleosomes in the rate at which they sedimented through sucrose gradients. We speculate that mammalian telomeres have a bipartite structure with unusual chromatin near the telomere terminus and a more canonical nucleosomal organization in the proximal part of the telomere.     

X-Linked mental retardation with fragile X. a pedigree showing transmission by apparently unaffected males and partial expression in female carriers

Summary A large family is reported in which mental retardation associated with the fragile site at Xq28 was found. Three normal males seemed to have transmitted the trait through their daughters to affected grandchildren.A total of 19 family members were investigated cytogenetically. Mentally retarded males showed macroorchidism and the fragile X. Three mentally retarded females were found, with the fragile X in a high percentage of cells; in contrast, the obligate carriers showed no or only few cells with the fragile X.     

A somatic cell hybrid panel and DNA probes for physical mapping of human chromosome 7p.

To identify by reverse genetics genes on the short arm of human chromosome 7 expected to be involved in the regulation of human craniofacial and limb development, we have set up a human mouse somatic cell hybrid panel that divides 7p into 9 fragments. The breakpoints are defined by deletions or translocations involving one chromosome 7 in the cells of the human cell fusion partners. Particularly densely covered with these cytogenetic anchor points is the proximal area of 7p within and around 7p13. The number of cytogenetic mapping points within proximal 7p could be increased by four, using two diploid human cell lines with small interstitial deletions in this region for dosage studies. We used Southern blots of this panel to assign to 7q or subregions of 7p more than 300 arbitrary DNA probes or genes that provide reference points for physical mapping of 7p. Three reciprocal translocations with one of the breakpoints in 7p13 mark the location of a gene involved in Greig cephalopolysyndactyly syndrome. To define an area in which we could identify candidates for this developmental gene, we established a macrorestriction map using probes flanking the putative gene region. The Greig translocations were found to be located within a 630-kb NotI restriction fragment.     

Production of Aseptic Spores of Vesicular-Arbuscular Endophytes and Their Viability After Chemical and Physical Stress

The survival of germinating spores of vesicular-arbuscular endophytes after treatments with oxidizing agents, antibiotics, moist heat, ultrasonic radiation, and ultraviolet radiation was compared with that of their contaminating microbes. Spores of three species were rapidly decontaminated by treatment with 0.42% (wt/vol) chlorine available from 5.0% (wt/vol) chloramine-T at 30°C for 20 to 40 min depending on the species and the soil from which they were extracted. This treatment did not change spore viability. The survival of spores was reduced by exposure for 20 min to 1.11% chlorine at 30°C for Glomus caledonius or at 35°C for Acaulospora laevis. Growth of any bacteria surviving treatment with oxidizing agents was inhibited by 100 μg of chloramphenicol per ml in agar; however, spore germination and germ tube growth were reduced only by concentrations greater than 200 μg/ml in agar. Spore germination was decreased by concentration of pimaracin, which controlled fungal growth. The spores survived moist heat at 40°C for 80 min, 55°C for 10 min, and 60°C for less than 1 min. The viability of spores was unaffected by ultrasonic irradiation for up to 4 min. Spores of G. caledonius and A. laevis were extremely resistant to ultraviolet radiation. Their viability was unaffected by exposure to 5 × 10⁸ ergs cm⁻² from an ultraviolet source of 253.7nm. The spores had very thick, pigmented walls, and the possibility that these provided some protection against the physical and chemical treatments is discussed. The degree of physiological damage to the spores caused by the treatments demonstrated some adverse effects of basic laboratory procedures. This information, together with that on the comparative sensitivity of contaminating microbes to the treatments, was used in the development of protocol for producing large numbers of uncontaminated spores.     

Airstream Fractionation of Vesicular-Arbuscular Mycorrhizal Fungi: Concentration and Enumeration of Propagules

Spores and fragments of vesicular-arbuscular mycorrhizal fungi in dry soils were concentrated up to 100-fold when the soils were partitioned by fluidization and elutriation with a series of upward airstreams at progressively increasing velocities. The propagules were transported with the finer soil particles according to their equivalent spherical diameters. The system was used to predict the transport of propagules by wind. Concentrated propagules were rapidly separated from the soil particles in each soil fraction by an aqueous flotation method. The technique is proposed as a quantitative method for estimating the numbers of spores and fragments of mycorrhizae. The scheme includes a viability test that was used to differentiate between potentially infective propagules and those that were either dormant or incapable of regrowth.     

Cloning,characterization and chromosomal localization of the Sus scrofa SLC31A1 gene

Copper is an essential element necessary for normal function of numerous enzymes in all living organisms. Uptake of copper into the cell is thought to occur through the membrane protein, SLC31A1 (CTR1), which has been described in a variety of species including yeast, human and mouse. In this study, we present cloning, gene structure, chromosomal localization and expression pattern of the Sus scrofa SLC31A1 gene, which encodes a 189 amino acid protein. The (SSC) SLC31A1 gene is organized in four exons and spans an approximately 2.3 kb genomic region. We have localized the gene to chromosome 1q28-q2.13 using a somatic cell hybrid panel. This region shows conservation of synteny with human chromosome 9, where the human SLC31A1 (CTR1) gene has been localized. Expression studies suggest that SLC31A1 mRNA is transcribed in all tissues examined.     

Mutations in autism susceptibility candidate 2 (AUTS2) in patients with mental retardation

We report on three unrelated mentally disabled patients, each carrying a de novo balanced translocation that truncates the autism susceptibility candidate 2 (AUTS2) gene at 7q11.2. One of our patients shows relatively mild mental retardation; the other two display more profound disorders. One patient is also physically disabled, exhibiting urogenital and limb malformations in addition to severe mental retardation. The function of AUTS2 is presently unknown, but it has been shown to be disrupted in monozygotic twins with autism and mental retardation, both carrying a translocation t(7;20)(q11.2;p11.2) (de la Barra et al. in Rev Chil Pediatr 57:549–554, 1986; Sultana et al. in Genomics 80:129–134, 2002). Given the overlap of this autism/mental retardation (MR) phenotype and the MR-associated disorders in our patients, together with the fact that mapping of the additional autosomal breakpoints involved did not disclose obvious candidate disease genes, we ascertain with this study that AUTS2 mutations are clearly linked to autosomal dominant mental retardation.     

The small RNA content of human sperm reveals pseudogene-derived piRNAs complementary to protein-coding genes

At the end of mammalian sperm development, sperm cells expel most of their cytoplasm and dispose of the majority of their RNA. Yet, hundreds of RNA molecules remain in mature sperm. The biological significance of the vast majority of these molecules is unclear. To better understand the processes that generate sperm small RNAs and what roles they may have, we sequenced and characterized the small RNA content of sperm samples from two human fertile individuals. We detected 182 microRNAs, some of which are highly abundant. The most abundant microRNA in sperm is miR-1246 with predicted targets among sperm-specific genes. The most abundant class of small noncoding RNAs in sperm are PIWI-interacting RNAs (piRNAs). Surprisingly, we found that human sperm cells contain piRNAs processed from pseudogenes. Clusters of piRNAs from human testes contain pseudogenes transcribed in the antisense strand and processed into small RNAs. Several human protein-coding genes contain antisense predicted targets of pseudogene-derived piRNAs in the male germline and these piRNAs are still found in mature sperm. Our study provides the most extensive data set and annotation of human sperm small RNAs to date and is a resource for further functional studies on the roles of sperm small RNAs. In addition, we propose that some of the pseudogene-derived human piRNAs may regulate expression of their parent gene in the male germline.