Effect of alloxan administration upon Channa punctatus (Bloch)

Channa punctatus, a fresh water teleost, was administered intramuscularly with alloxan in doses varying between 200 and 600 mg/kg body weight. The course of cytological events occurring in the islets of alloxanized fish was followed over a period of 120 hours post injection. Alloxan caused mild degranulation of some of the beta cells in the beginning but later nuclear pycnosis, vacuolization and necrosis of the beta cells was observed. Like other vertebrates, Channa punctatus is alloxan-sensitive and its islet beta cells are susceptible to the cytotoxic effects of alloxan.     

Development of a radioimmunoassay for quantitation of calregulin in bovine tissues

Experimental conditions are described for a convenient and simple one-step method for radioimmunoassay (RIA) of the calcium binding protein calregulin [Waisman, D.M., Salimath, B.P., & Anderson, M.J. (1985) J. Biol. Chem. 260, 1652-1660]. The radioimmunoassay utilizes 125I-labeled calregulin and pansorbin cells (Staphylococcus aureus) coated with rabbit anti-calregulin antibody. Binding equilibrium is attained in 30 min, and the total time of the assay is 1 h. The assay is sensitive to about 30 fmol of calregulin. Calregulin was quantitated in various bovine tissue extracts and was detected in all tissues except erythrocytes. It was present in particularly high amounts in pancreas (540 micrograms/g of tissue), liver (375 micrograms/g of tissue), and testis (256 micrograms/g of tissue). While about 80% of the total tissue calregulin is soluble, about 20% of this protein was found to be associated with particulate fractions. Unmasking of particulate calregulin required the presence of nonionic detergent. Gel permeation chromatography of bovine brain 100 000 g supernatant in the presence or absence of calcium has resolved a single peak of calregulin by RIA. In addition, the distribution of calregulin in the soluble or particulate fraction of bovine brain was unaffected by the presence or absence of calcium during homogenization, suggesting that calregulin does not form either calcium-dependent or calcium-independent association with soluble or particulate proteins. These results identify calregulin as a major tissue Ca2+ binding protein.     

Biochemical Aspects of Parasitism by the Angiosperm Parasites: Phenolics in Parasites and Hosts

the contents of total phenolics in three parasitic angiosperms, Cuscuta species, Orobanche aegyptiaca and Dendrophthoe falcata and their respective hosts, were colorimetrieally determined. A biochemical comparison was made of the phenolics on the basis of the ability of alcoholic extracts of the tissues to inhibit amylose phosphorylase in vitro. High concentration of phenolics seemed to be a general feature of parasitic angiosperms. An increase in the concentration of the phenolics occurred in the tissues of infected hosts, in comparison with controls. the phenolics of Orobanche and mistletoe had inhibitory activity against amylose phosphorylase, but those of Cuscuta developed the inhibitory ability only when growing on hosts which themselves possessed inhibitory phenolics. the inhibitory activity of host phenolics was sometimes altered as a result of infection by parasite. Although the hosts often exerted some influence on the concentration and the inhibitory activity of phenolics in the parasites, there was no direct relationship between host and parasite phenolics. the sum of the phenolics in the tissues of parasite and the infected bost generally exceeded the phenolics in the tissues of the control host. The content of phenolics and their inhibitory activity did not appear to be directly related to the resistance of a host or to the extent of its susceptibility to parasite infection.     

Purification,characterization and cloning of an endo-1,4-B-glucanase fromRuminococcus sp.

Endoglucanase ofRuminococcus sp. is composed of seven active protein components when chromatographed on an ion exchange column (Q-Sepharose). Component I (endoglucanase A) did not bind to the column and was purified to homogeneity by molecular sieve chromatography. It had a mol. wt. of 22 000. Component II was fractionated into two active protein peaks (endoglucanase B and C) having mol. wt. of 225 000 and 10 000. The endoglucanase A had high affinity for CMC (Km 8 mg/ml). The temperature optimum of all three endoglucanase was between 40–45°C. The gene encoding for endolucanase activity was cloned inE. coli HB101 with pBR322. A 4.3 kilobaseBamH1 fragment encoding endoglucanase was hybridized toRuminococcus chromosomal DNA.     

Histaminergic mechanisms in experimental convulsions

Effect of some histamine (HA) agonists and antagonists were assessed on electroshock (MES) convulsions in mice and rats. In mice, pretreatment with the HA precursor, l-histidine (100, 500 and 1000 mg/kg) precipitated seizures after a subthreshold (30 mA) stimulus. Both incidence (%) and tonic hind limb extensor phase (THE) were more than that in vehicle treated controls. The H1 blockers, pheniramine (25 mg/kg) and promethazine (25 mg/kg) both protected against (60 mA) MES and both incidence of convulsions and THE were reduced. A similar protective effect was not seen with either the H2 blocker, cimetidine (up to 200 mg/kg), or atropine (1 mg/kg). In rats, both the classical antihistamines blocked MES seizures, whereas, the H2-blocker, cimetidine, and atropine were, ineffective. Further, both H1 blockers were ineffective in antagonizing seizures induced by pentylenetetrazole, INH, caffeine or strychnine. These results are discussed in light of a possible HA-ergic regulation of experimental convulsions.