Affected sib-pair analysis of the GLUT1 glucose transporter gene locus in non-insulin-dependent diabetes mellitus (NIDDM): evidence for no linkage

Despite the strong evidence for a major role played by genetic factors in the aetiology of non-insulin-dependent diabetes mellitus (NIDDM), the genes involved are still unknown. Association studies of candidate genes for the inheritance of NIDDM have so far yielded inconclusive results. Some evidence exists for an association between NIDDM and the glucose transporter gene GLUT1, involved in basal glucose transport, although this has not been confirmed. In the present study we have tested the hypothesis of linkage between NIDDM and the GLUT1 gene, using affected sib-pairs. With this method the concordance observed for a given gene marker is compared with that expected under the assumption of no linkage between that marker and the disease. Fifty-four pedigrees (22 Italians and 32 British), for a total of 82 sibpairs were studied by the affected sib-pair method proposed by Weeks and Lange, using two restriction fragment length polymorphisms (RFLPs) at the GLUT1 locus, the MspI RFLP, at an estimated 0.171 recombination frequency from the GLUT1 gene, and the XbaI RFLP, located within the GLUT1 gene and previously shown to be associated with the disease. Results showed that the MspI marker and NIDDM segregate independently; for the XbaI RFLP, linkage could be shown only if the results were weighted by the allele frequency [f(p) = 1/p], and only in the Italian and the combined (Italian and British) sib-pair groups. Multilocus analysis with both markers was also negative. We conclude that the GLUT1 gene is very unlikely to play a major role in the aetiology of NIDDM, although an accessory role cannot be excluded, and studies of the gene sequence should help to clarify this question.     

The human glucagon receptor encoding gene: structure, cDNA sequence and chromosomal localization

Characterization of the human glucagon-receptor-encoding gene (GGR) should provide a greater understanding of blood glucose regulation and may reveal a genetic basis for the pathogenesis of diabetes. A cDNA encoding a complete functional human glucagon receptor (GGR) was isolated from a liver cDNA library by a combination of polymerase chain reaction and colony hybridization. The cDNA encodes a receptor protein with 80% identity to rat GGR that binds [¹²⁵I] glucagon and transduces a signal leading to increases in the concentration of intracellular cyclic adenosine 3′,5′-monophosphate. Southern blot analysis of human DNA reveals a hybridization pattern consistent with a single GGR locus. In situ hybridization to metaphase chromosome preparations maps the GGR locus to chromosome 17q25. Analysis of the genomic sequence shows that the coding region spans over 5.5 kb and is interrupted by 12 introns.     

Intergenic spacers of rRNA genes in three species of theCynareae (Asteraceae)

Intergenic spacers of the rRNA genes of three species of theCynareae tribe:Cynara cardunculus subsp.scolymus (artichoke),Onopordum acanthium, andO. illyricum were cloned in the plasmid pGEM-7zf(+). Detailed restriction mapping and partial sequencing of the IGSs were carried out. The structural analysis showed a clear diversity betweenCynara andOnopordum, while a high degree of homology was found between the twoOnopordum spp. In all three species a fragment of about 450 bp from the 5 end of 18S to the Acc I site with a high sequence homology was present. Nucleotide sequences upstream from the above mentioned Acc I site show a gradual decrease of homology betweenCynara andOnopordum.     

Effect of the pheromone biosynthesis activating neuropeptide on sex pheromone biosynthesis in Spodoptera littoralis isolated glands

The control of Spodoptera littoralis sex pheromone biosynthesis has been investigated with synthetic pheromone biosynthesis activating neuropeptide (PBAN) and different labeled tracers using an in vitro isolated gland system. Responsiveness of the glands to PBAN stimulation was impaired by careless tissue manipulation. The fact that PBAN is active in the isolated gland system suggests that this might be a target organ for this peptide in S. littoralis. As reported previously with Br-SOG extracts and intact females, label incorporation into the pheromone increased in glands treated with PBAN from all the precursors tested. However, the formation of labeled intermediates from d₅E11–14:Acid also occurred in glands incubated in the absence of the peptide, but the amounts of d₅Z9, E11–14:Acid were lower in PBAN treated glands than in controls. These results indicate that PBAN controls pheromone biosynthesis in S. littoralis by regulating the reduction of acyl moieties. © 1994 Wiley-Liss, Inc.     

Magnesium-deficiency potentiates free radical production associated with postischemic injury to rat hearts: Vitamin E affords protection

Preexisting magnesium deficiency may alter the susceptibility of rat hearts to postischemic oxidative injury (free radicals). This was examined in rats maintained for 3 weeks on a magnesium-deficient (Mg-D) diet with or without concurrent vitamin E treatment (1.2 mg/day, SC). Magnesium-sufficient (Mg-S) rats received the same diet supplemented with 100 mmol Mg/kg feed. Following sacrifice, isolated working hearts were subjected to 30-, 40-, or 60-min global ischemia and 30-min reperfusion. Postischemic production of free radicals was monitored using electron spin resonance (ESR) spectroscopy and spin trapping with -phenyl-N-tert butylnitrone (PBN, 3 mM final); preischemic and postischemic effluent samples were collected and then extracted with toluene. PBN/alkoxyl adduct(s) (PBN/RO·; _H = 1.93 G,_N = 13.63 G) were the dominant signals detected in untreated Mg-S and Mg-D postischemic hearts, with comparably higher signal intensities observed for the Mg-D group following any ischemic duration. Time courses of postischemic PBN/RO· detection were biphasic for both groups (maxima: 2–4 and 8.5–12.5 min), and linear relationships between the extent of PBN/RO· production and the severity of both mechanical dysfunction and tissue injury were determined. Following each duration of ischemia, Mg-D hearts displayed greater levels of total PBN adduct production (1.7 –2.0 times higher) and lower recovery of cardiac function (42–48% less) than Mg-S hearts. Pretreating Mg-D rats with vitamin E prior to imposing 40-min ischemia/reperfusion, led to a 49% reduction in total PBN/RO· production, a 55% lower LDH release and a 2.2-fold improvement in functional recovery, compared to untreated Mg-D hearts. These data suggest that magnesium deficiency predisposes postischemic hearts to enhanced oxidative injury and functional loss, and that antioxidants may offer significant protection against pro-oxidant influence(s) of magnesium deficiency.     

Replication of the promiscuous plasmid pLSI: a region encompassing the minus origin of replication is associated with stable plasmid inheritance

Deletion of a region of the promiscuous plasmid pLS1 encompassing the initiation signals for the synthesis of the plasmid lagging strand led to plasmid instability in Streptococcus pneumoniae and Bacillus subtilis. This defect could not be alleviated by increasing the number of copies (measured as double-stranded plasmid DNA) to levels similar to those of the wild-type plasmid pLS1. Our results indicate that in the vicinity of, or associated with the single-stranded origin region of pLS1 there is a plasmid component involved in its stable inheritance. Homology was found between the DNA gyrase binding site within the par region of plasmid pSC101 and the pLS1 specific recombination site RS_R.     

Thermostable β-Glycosidase from Sulfolobus Solfataricus

The Sulfolobus solfataricus β-glycosidase (Sβgly) is a thermostable and thermophilic glycosyl-hydrolase with broad substrate specificity. The enzyme hydrolizes β-D-gluco-, fuco-, and galactosides, and a large number of /Winked glycoside dimers and oligomers, linked β1-3, β1-4, and β1-6, It is able to hydrolize oligosaccharides with up to 5 glucose residues. Furthermore, it is also able to promote transglycosylation reactions. The corresponding gene has been cloned and overexpressed both in yeast and Escherichia coli. Based on sequence and functional data, the Sβgly has been assigned to the so-called BGA family of glycosyl-hydrolases, including β-glycosidases, β-galactosidases and phosho-β-galactosidases from mesophilic and thermophilic organisms of the three domains. The Sβgly has been crystallized and the resolution of its structure is in progress. Because of its special properties, the enzymes has considerable biotechnological potential.     

The placement, recovery, and loss of scatter hoards by eastern chipmunks,Tamias striatus

Although eastern chipmunks typically larder hoard food in theirburrows, some scatter hoarding occurs, especially by newly emergedjuveniles and by females with young. To examine patterns ofscatter hoard placement and their adaptive significance, weused standard food provisioning tests followed by continuousmonitoring to determine the longevity and fate of scatter hoards.Longevity of scatter hoards was low (median 74 min) and pilferagewas high (46%). Chipmunks placed scatter hoards away from thepatch, closer to their burrow and within the defended area ofprimary use. Scatter hoard placement was affected by the numberof competitors at the patch. However, juveniles and femaleswith young differed slightly in their responses. competitorsthat approached scatteihoards were sometimes chased away bythe scatter hoard's owner, and the scatter hoard was moved toanother location by the owner. Females with young recoveredtheir largest scatter hoards first, but there was little additionalpattern in scatter hoard recovery. An experiment using simulatedscatter hoards showed that scatter hoards farther from a patchof food lasted longer and that disturbing and marking scatterhoards reduced their longevity. These observations indicate:(1) that scatter hoard placement is more related to avoidingpilferage of completed caches than to rapidly sequestering fooditems from an ephemeral patch and (2) that optimal cache distributionmay be affected by the cache-defense ability of individuals,by the relationship between competitor density and cache securitynear the patch, and by the territorial behavior of neighboringconspecifics.     

Tissue Fixation for Immunohistochemical Detection of Proliferating Cell Nuclear Antigen with PC10 Monoclonal Antibody

PC10 is a monoclonal antibody to proliferating cell nuclear antigen, a nuclear protein associated with the cell cycle. We have evaluated the effects of tissue fixation on PC10 immunoreactivity in sections of paraffin embedded rat tissues. Immunoreactivity was well preserved in tissues after fixation with alcohol-based solutions for 3-24 hr. Fewer PC10-positive cells were detectable in samples fixed with formaldehydecontaining solutions compared with samples fixed with alcohol for the same time. Loss of PC10 immunoreactivity in formaldehyde fixed tissues was progressive, and quantifiable as early as after 3 hr fixation. Consequently, alcohol-based fixatives are strongly recommended for any immunocytochemical prospective study using PC10 antibody. In contrast, loss of PC10-immunoreactivity is always predictable, but difficult to quantitate, using formaldehyde fixed specimens. This aspect should be considered when using PC10 antibody in retrospective studies with routinely-processed archival material.     

The Peripheral-Type Benzodiazepine Receptor Ligands [3H]Ro 5-4864 and [3H]PK 11195 Bind to the Retina of Rabbit, but Not of Turtle

Abstract: The binding of [³H]flunitrazepam, [³H]RO 5-4864, and [³H]PK 11195 to membrane preparations of the retina was studied in the turtle and rabbit. Only a single population of [³H]flunitrazepam binding sites was detected in the turtle, whereas two populations appeared to be present in the rabbit. No specific binding for [³H]RO 5-4864 and [³H]PK 11195 could be detected in the turtle. In rabbit, both ligands bound with high affinity, revealing a significant population of binding sites (K_D values of 24 ± 2.3 and 2.2 ± 0.8 nM, and B_max values of 440 ± 35 and 1,482 ± 110 fmol/mg of protein, respectively). The binding was temperature - and protein-dependent. Displacement studies showed a similar rank order of potency of various unlabeled ligands against both [³H]RO 5-4864 and [³H]PK 11195 (PK 11195 > Ro 5-4864 > flunitrazepam > flumazenil). These results suggest that peripheral-type benzodiazepine receptors are present in the retina of the rabbit, but not of the turtle.