Nucleotide and deduced amino acid sequence of bovine adrenal medulla chromogranin B (secretogranin I)

1. A novel 1745-dalton pyroglutamyl peptide (BAM-1745)6 was recently isolated and characterized from bovine adrenal medulla chromaffin granules. Its amino acid sequence was found to be 93% identical to residues 580-593 of human chromogranin B (secretogranin I). 2. Based on this sequence a degenerate oligonucleotide probe was synthesized and used to identify a 2.4-kb bovine adrenal medulla chromogranin B cDNA. 3. The deduced polypeptide is 647 amino acids long and begins with a putative signal sequence of 20 residues as in the human, rat, and mouse proteins. Also conserved in the bovine protein is a tyrosine residue which may be sulfated, two N-terminal cysteines, and many paired basic amino acids which may serve as sites of posttranslational processing. The peptide BAM-1745 is flanked by paired basic amino acids and therefore is most likely a product of posttranslational processing. Bovine chromogranin B is 67, 58, and 58% identical to the human, rat, and mouse chromogranin B proteins, respectively. 4. The carboxyl terminus of bovine chromogranin B, including BAM-1745, was found to be the most conserved region of the polypeptide and may identify it as an important functional domain.     

Lipogenesis from n-butyrate in colonocytes

Cell membranes of colonic epithelial cells (CEC) in ulcerative colitis show structural abnormalities which are specific to the disease and which suggest impaired lipogenesis in CECs. Lipogenesis from [1-¹⁴C]-n-butyrate, the chief oxidative fuel of colonic epithelial cells, was measured in isolated CECs under control conditions, with or without glucose and in the presence of mercaptoacetate, a major reducing agent in the colonic lumen- Glucose significantly (p < 0.01) stimulated lipogenesis from [1-¹⁴C]-butyrate which was reversed by 5 mM mercaptoacetate. Mercaptoacetate significantly diminished CEC thiolase activity (EC 2.3.1.9). 5-Aminosalicylic acid reversed the adverse effects of mercaptoacetate in the saponifiable fraction of extracted lipids. Changes in lipogenesis due to colonic luminal reducing agents would affect the barrier function of CECs a feature relevant to the disease process of ulcerative colitis.     

The swi4+ gene of Schizosaccharomyces pombe encodes a homologue of mismatch repair enzymes.

The swi4+ gene of Schizosaccharomyces pombe is involved in termination of copy-synthesis during mating-type switching. The gene was cloned by functional complementation of a swi4 mutant transformed with a genomic library. Determination of the nucleotide sequence revealed an open reading frame of 2979 nucleotides which is interrupted by a 68 bp long intron. The putative Swi4 protein shows homology to Duc-1 (human), Rep-3 (mouse), HexA (Streptococcus pneumoniae) and MutS (Salmonella typhimurium). The prokaryotic proteins are known as essential components involved in mismatch repair. A strain with a disrupted swi4+ gene was constructed and analysed with respect to the switching process. As in swi4 mutants duplications occur in the mating-type region of the swi4 (null) strain, reducing the efficiency of switching.     

Trans replication and high copy numbers of wheat dwarf virus vectors in maize cells.

The replication of shuttle vectors derived from Wheat Dwarf Virus, a monopartite geminivirus, was studied in cultured maize endosperm cells, and in the Black Mexican Sweet (BMS) maize cell line. Using in vivo labeling and DNA methylation analysis, we showed that replication was initiated within 24 hrs after transfection, and did not require cell division in both cell lines. Copy numbers of 30,000 ds DNA molecules per cell were observed in endosperm cells after three days. The replication protein was shown to act in trans, since the wild type gene of the shuttle vector enabled replication-deficient vectors carrying mutated genes to replicate. These properties suggest that WDV may have similar applications in plants as SV40 in mammalian cells.     

Seismic signal transmission between burrows of the Cape mole-rat,Georychus capensis

Summary Both seismic and auditory signals were tested for their propagation characteristics in a field study of the Cape mole-rat (Georychus capensis), a subterranean rodent in the family Bathyergidae. This solitary animal is entirely fossorial and apparently communicates with its conspecifics by alternately drumming its hind legs on the burrow floor. Signal production in this species is sexually dimorphic, and mate attraction is likely mediated primarily by seismic signalling between individuals in neighboring burrows. Measurements within, and at various distances away from, natural burrows suggest that seismic signals propagate at least an order of magnitude better than auditory signals. Moreover, using a mechanical thumper which could be triggered from a tape recording of the mole-rat's seismic signals, we established that the vertically-polarized surface wave (Rayleigh wave) propagates with less attenuation than either of the two horizontally-polarized waves. Thus, we tentatively hypothesize that Rayleigh waves subserve intraspecific communication in this species.Abbreviations PPM pulses per min - SB simulated burrow - SD standard deviation - SPL sound pressure level