Tandem duplication of the NF1 gene detected by high-resolution FISH in the 17q11.2 region

The gene for neurofibromatosis type 1 (NF1), mapping to 17q11.2, has one of the highest observed mutation rates, partially because of its large size and gene conversion primed by NF1 pseudogenes. We have previously shown by means of high resolution fluorescence in situ hybridization (FISH) that a number of the loci flanking the NF1 gene are duplicated, in agreement with the reported presence of NF1 repetitive sequences (REPs). We report a direct tandem duplication of the NF1 gene identified in 17q11.2 by high-resolution FISH. FISH on stretched chromosomes with locus-specific probes revealed the duplication of the NF1 gene from the promoter to 3'UTR, but with at least the absence of exon 22. Fiber FISH with P1 artificial and bacterial artifical chromosomes, including the NF1 5'UTR and 3'UTR and flanking regions, visualized the direct tandem duplication with a similar, but not identical, genomic organization of the NF1 duplicon copies. Duplication was probably present in the human-chimpanzee-gorilla common ancestor, as demonstrated here by the finding of the duplicated NF1 gene at orthologous chromosome loci. The NF1 intrachromosomal duplication may contribute to the high whole-gene mutation rate by gene conversion, although the functional activity of the NF1 copy remains to be investigated. Detection of the NF1 duplicon by high-resolution FISH may pave the way to filling the gaps in the human genomic sequence of the pericentromeric 17q11.2 region.     

Correlation of the Insecticidal Activity of the Bacillus thuringiensis A4 Strain Against Bactrocera oleae (Diptera) with the 140-kDa Crystal Polypeptide

The crystals of the soil-isolated Bacillus thuringiensis (Bt) strain A4 consist of two polypeptides with molecular mass of 140 kDa and 32 kDa that exhibit insecticidal activity against adult flies of Bactrocera oleae (Diptera). Plasmid curing applied to this strain resulted in the isolation of several subclones exhibiting alterations in their crystal polypeptides as well as two acrystalliferous subclones. The crystals of subclone 1.1 lacked the 32-kDa polypeptide and consisted uniquely of a 140-kDa polypeptide antigenically related to the parental 140-kDa crystal polypeptide. Additionally, the crystals of this subclone exhibited insecticidal activity against B. oleae equivalent to that of the parental strain. Therefore, the 32-kDa crystal polypeptide is dispensable for insecticidal activity, which appears to be dependent on the presence of the 140-kDa crystal polypeptide. Received: 5 April 2000 / Accepted 2 May 2000     

Changes in serum copper level during detoxification of acutely poisoned drug addicts

Although it is known that drug addicts are a high-risk group for disruption of many homeostatic processes, little is know about changes in serum trace elements concentrations after taking the psychoactive substances. The aim of the study was to check the influence of the taking homemade heroin on serum level of copper. Blood samples were taken from 30 opiate addicts, and copper concentrations were measured by the means of atomic absorption spectrophotometry. The result of the study show that in the examined group, copper serum concentrations (1.35 mg/L) upon admission to the clinic were higher than in the control group (1.11 mg/L) but decreased during hospitalization (1.18 mg/L). There was no correlation between duration of stay at the hospital and changes in serum copper concentration.     

Biosynthesis of glycoproteins in Candida albicans: Solubilization and partial characterization of dolichol phosphate mannose synthase and protein mannosyl transferases

Incubation of a mixed membrane fraction isolated from C. albicans yeast cells with Nonidet P-40 at a detergent/protein ratio as low of 0.025 (0.016–0.019%, w/v) yielded a soluble fraction that catalyzed the transfer of mannose from GDP-[¹⁴C] Man into dolichol phosphate mannose and from this intermediate into mannoproteins. Over 95% of the sugar in mannoproteins was O-linked as judged from its release after -elimination. Mannose was identified as the sole product after this treatment. Transfer activity did not depend on exogenous lipid acceptor indicating that the latter was solubilized along with the mannosyl transferases. Synthesis of mannolipid and mannoproteins occurred at optima temperatures of 20 °C and 37 °C, respectively, and at a pH in the range of 7.5-9.5. Mannosyl transfer into the mannolipid was stimulated by Mg²⁺and inhibited by Ca²⁺and Mn²⁺whereas mannoprotein labeling was stimulated by Mn²⁺and to a lower extent by Mg²⁺. When measured as a function of substrate concentration, the synthesis of the mannolipid was a nearly linear function of GDP-Man concentration in the range of 5 to 32 M whereas protein mannosylation exhibited hyperbolic kinetics with saturation reached at about 10 M. The solubilized preparation was able to utilize an exogenous source of mannolipid as sugar donor for protein mannosylation. Dinucleotides and, to a higher extent trinucleotides, inhibited mannosyl transfer into the mannolipid and hence into mannoproteins.     

A new species of Sorghastrum (Poaceae) from Isla Socorro, Colima, Mexico

A new species ofSorghastrum,S. pohlianum, from Mexico is described and illustrated. A numerical analysis comparing the new species to the closest species (S. nutans andS. nudipes) was undertaken. The first three principal components explain 84% of the variation of the taxa involved. In addition there is morphological evidence to distinguish the new species from its closest relatives. It differs fromS. nutans by showing smaller inflorescences, having sterile lemmas and anthers, and having somewhat smaller but wider blades and different flowering periods. In addition, it is distinguished fromS. nudipes due to the presence of auricles > 1 mm long and inflorescence branches bearing spikelets along their entire length.     

Identification of rCop-1, a New Member of the CCN Protein Family,as a Negative Regulator for Cell Transformation

By using a model system for cell transformation mediated by the cooperation of the activated H-ras oncogene and the inactivated p53 tumor suppressor gene, rCop-1 was identified by mRNA differential display as a gene whose expression became lost after cell transformation. Homology analysis indicates that rCop-1 belongs to an emerging cysteine-rich growth regulator family called CCN, which includes connective-tissue growth factor, CYR61, CEF10 (v-src inducible), and the product of the nov proto-oncogene. Unlike the other members of the CCN gene family, rCop-1 is not an immediate-early gene, it lacks the conserved C-terminal domain which was shown to confer both growth-stimulating and heparin-binding activities, and its expression is lost in cells transformed by a variety of mechanisms. Ectopic expression of rCop-1 by retroviral gene transfers led to cell death in a transformation-specific manner. These results suggest that rCop-1 represents a new class of CCN family proteins that have functions opposing those of the previously identified members.Oncogenic conversion of a normal cell into a tumor cell requires multiple genetic alterations (12). Of particular interest is the fact that mutations in both ras oncogenes (3) and the p53 tumor suppressor gene cooperate in transformation of mammalian cells (11). Mutations in both ras and the p53 gene were also found at high frequencies in a variety of human cancers, including those of the colon, lung, and pancreas (2, 18). It has been proposed that both p53 and Ras function, whether directly or through other signaling molecules, to control expression of genes that are important for cell growth and differentiation (13, 17, 37). To this end, several ras target genes (10) and p53 target genes, including those encoding p21/CIP1/WAF1, an inhibitor of G₁ cyclin-dependent kinase (9); Mdm-2, a negative regulator of p53 (1); GADD45, a protein involved in DNA repair (36); and Bax, which promotes apoptosis (28), have been identified. Most of these genes, except p21/CIP1/WAF1, which was cloned by subtractive hybridization, were identified by the candidate gene hypothesis. Recently, more p53 target genes have been isolated by the differential display technique, including those coding for cyclin G (31); MAP4, a microtubule-associated protein negatively regulated by p53 (29); and PAG608, a novel nuclear zinc finger protein whose overexpression promotes apoptosis (14). Functional characterizations of these genes have shed light on the role of p53 in cell cycle control and apoptosis. However, genes that mediate tumor suppression activity by p53 remain elusive.The fact that neither the inactivation of p53 nor the activation of Ras alone is able to transform primary mammalian cells (34), whereas both mutations together can do so, suggests that genes regulated by p53 and Ras cooperate in upsetting normal cell growth control cells (11). Using differential display (22), we set out to identify genes whose expression is altered by both mutant ras and p53 by comparing the mRNA expression profiles of normal rat embryo fibroblasts (REFs) and their derivatives transformed by either a constitutively inactivated or a temperature-sensitive mutant p53 in cooperation with the activated H-ras oncogene (11, 27). In this report we describe the identification and give a functional characterization of rCop-1, a gene whose expression is abolished by cell transformation. By sequence homology, rCop-1 was found to belong to an emerging cysteine-rich growth regulator family called CCN (which stands for connective-tissue growth factor [CTGF], CEF10/Cyr61, and Nov) (4). Here we show that rCop-1 may represent a novel class of CCN family proteins based on its unique cell cycle expression pattern, its lack of the C-terminal (CT) domain conserved in all CCN proteins, its loss of expression in all transformed cells analyzed, and its ability to confer cytotoxicity to the transformed cells.     

Selective activity against Mycobacterium tuberculosis of new quinoxaline 1,4-di-N-oxides

New series of 3-phenylquinoxaline 1,4-di-N-oxide with selective activity against Mycobacterium tuberculosis have been prepared and evaluated. Thirty-four of the seventy tested compounds showed an MIC value less than 0.2 μg/mL, a value on the order of the MIC of rifampicin. Furthermore, 45% of the evaluated derivatives showed a good in vitro activity/toxicity ratio. The most active and selective compounds carry a fluorine atom in the quinoxaline 7-position or in the phenyl substituent para-position. In conclusion, the potency, low cytotoxicity and selectivity of these compounds make them valid lead compounds for synthesizing new analogues, particularly compound 7-methyl-3-(4’-fluoro)phenylquinoxaline-2-carbonitrile 1,4-di-N-oxide (MIC <0.2 μg/mL and SI >500).     

Antibodies to the Core Proteins of Nairobi Sheep Disease Virus/Ganjam Virus Reveal Details of the Distribution of the Proteins in Infected Cells and Tissues

Nairobi sheep disease virus (NSDV; also called Ganjam virus in India) is a bunyavirus of the genus Nairovirus. It causes a haemorrhagic gastroenteritis in sheep and goats with mortality up to 90%. The virus is closely related to the human pathogen Crimean-Congo haemorrhagic fever virus (CCHFV). Little is currently known about the biology of NSDV. We have generated specific antibodies against the virus nucleocapsid protein (N) and polymerase (L) and used these to characterise NSDV in infected cells and to study its distribution during infection in a natural host. Due to its large size and the presence of a papain-like protease (the OTU-like domain) it has been suggested that the L protein of nairoviruses undergoes an autoproteolytic cleavage into polymerase and one or more accessory proteins. Specific antibodies which recognise either the N-terminus or the C-terminus of the NSDV L protein showed no evidence of L protein cleavage in NSDV-infected cells. Using the specific anti-N and anti-L antibodies, it was found that these viral proteins do not fully colocalise in infected cells; the N protein accumulated near the Golgi at early stages of infection while the L protein was distributed throughout the cytoplasm, further supporting the multifunctional nature of the L protein. These antibodies also allowed us to gain information about the organs and cell types targeted by the virus in vivo. We could detect NSDV in cryosections prepared from various tissues collected post-mortem from experimentally inoculated animals; the virus was found in the mucosal lining of the small and large intestine, in the lungs, and in mesenteric lymph nodes (MLN), where NSDV appeared to target monocytes and/or macrophages.