Biosynthesis of lipids in chloroplasts isolated from jack pine needles

Suspensions of isolated pine needle chloroplasts were shown to incorporate galactose from UDP galactose-[¹⁴C] into galactolipids. The incorporation of the label among galactolipids was always considerably higher in the monogalactosyl diglycerides than in the digalactosyl diglycerides. The galactosyl incorporation into both galactolipid fractions was optimal at pH 8.0 and was inhibited by sulphydryl reagents (p-chloromercuribenzoate, N-ethyl maleimide and CdCl₂). The chloroplast preparations were also able to biosynthesize various phospholipids and galactolipids from palmitoyl-[1-¹⁴C]-CoA; the major portion of the label appeared in phosphatidyl choline. The incorporation of palmitic-[1-¹⁴C] acid into various lipids was very poor compared to that of palmitoyl-[1-¹⁴C]-CoA. However, addition of ATP and CoA markedly stimulated lipid biosynthesis from palmitic-[1-¹⁴C] acid, suggesting the presence of activating enzymes. These chloroplast suspensions did not show any de novo fatty acid synthesis.     

Effect of sulfur-containing compounds on anaerobic degradation of cellulose to methane by mixed cultures obtained from sewage sludge

Tests were made to determine the effects of inorganic and organic sulfur sources on the degradation of cellulose to methane in a chemically defined medium with sulfur-poor inoculum prepared from sewage sludge. The results show that a sulfur source of about a 0.85 mM concentration is essential for the degradation of cellulose to CH4. However, the production of CH4 from CO2 and H2 provided in the headspace occurred with 0.1 mM sulfate or sulfide. At a 9 mM concentration, all inorganic sulfur compounds other than sulfate inhibited both cellulose degradation and methane formation, and this inhibition increased in the order thiosulfate less than sulfite less than sulfide less than H2S. It appears that the degradation of cellulose to CH4 in a sulfate-free medium by inoculum maintained in a low-sulfur medium is inhibited because of the lack of availability of sulfur for growth of bacteria and synthesis of cell materials and sulfur-containing cofactors involved in cellulose degradation and methanogenesis. The reduction of methanogenesis by higher levels of sulfate probably occurs as a result of stimulation of reactions converting acetate and H2 to end products other than CH4.     

Value of stool examination in patients with diarrhoea.

Findings of stool examinations in 1593 patients with diarrhoea due to a single enteric pathogen--enterotoxigenic Escherichia coli rotavirus, Shigella, Campylobacter jejuni, Vibrio cholerae 0:1, Entamoeba histolytica, or Giardia lamblia--were reviewed to determine how well they predicted the agent associated with the diarrhoea. Specimens were examined visually for blood and mucus, tested for pH, and examined under a microscope for the presence of red and white blood cells, parasites, and stool fat. Although visible blood was more common in specimens from patients infected with Shigella (51%) and Ent histolytica (39%) than in those from patients infected with other agents (6%; p less than 0.01), patients infected with Shigella were most likely to have numerous faecal leucocytes (greater than 50/high power field: 39% v 8% of all patients and 7% of patients infected with Ent histolytica, p less than 0.01 in both cases). Patients infected with enterotoxigenic E coli, rotavirus, V cholerae 0:1, or C jejuni had loose stools with fewer red or white cells. Patients infected with rotavirus and C jejuni were more likely to have acid stools with 3 to 4+ fat, but these findings were related to young age and breast feeding. Stool examination is most useful in establishing a diagnosis of dysentery and in helping to distinguish between patients infected with Shigella and Ent histolytica; it is of limited usefulness in discriminating between pathogens causing watery diarrhoea.     

Chemical modification studies on Ricinus communis (Castor Bean) agglutinin

Ricinus communis agglutinin was subjected to various chemical treatments and the effect on its hemagglutinating and saccharide-binding properties was studied. Acetylation, succinylation and citraconylation led to a complete loss in the activity of the agglutinin, whereas reductive methylation had no effect on the activity, showing that charged amino groups were involved in the hemagglutinating and saccharide-binding activity of Ricinus agglutinin. Modification of tryptophyl, arginyl and carboxyl-group-containing residues did not lead to any loss in the activity of the agglutinin. Acetylation of tyrosyl groups with N-acetylimidazole strongly reduced the hemagglutinating and saccharide-binding property of Ricinus agglutinin. The loss in activity was restored on deacetylation of the tyrosyl groups. Modification of tyrosyl residues also led to a change in the immunological properties of the agglutinin. The initial rate of modification of tyrosyl and amino groups and the concomitant loss of activity was reduced in the presence of lactose.     

Phage P22 helps phage MB78 to overcome blockage of DNA maturation in rifampicin-resistant host

Bacteriophage MB78, a virulent phage ofSalmonella typhimurium cannot grow in rifampicin-resistant mutant (rif-39) of the host having altered RNA polymerase. The temperate phage P22 which cannot multiply in presence of the virulent phage MB78 can, however, help MB78 to overcome replication inhibition in rif-39. The processing of concatemeric phage DNA to monomer is blocked in this nonpermissive host. Superinfection with P22 induces synthesis of at least five P22 specific polypeptides which help phage MB78 in the processing of the concatemeric DNA and maturation of phage particles.     

Exogeneous diacylglycerols downregulate the activity of Na-K pump in Xenopus laevis oocytes

In this study, cell permeable diacyglycerols, sn-1,2-dioctanoglycerol (DiC8), and sn-1-oleoyl-2-acetylglycerol (OAG) were found to downregulate the activity of Na⁺-K⁺ pump in Xenopus laevis oocytes. Both DiC8 and OAG decreased the binding of [³H]ouabain to intact oocytes while phorbol esters did not appreciably influence the same. These diacylglycerols inhibited the amiloride-sensitive ²²Na⁺ influx and ouabain-sensitive ⁸⁸Rb⁺ uptake in the oocytes. Furthermore, DiC8 prevented the ²²Na⁺ efflux from the oocytes preloaded with ²²Na⁺. Addition of H-7 to DiC8- and OAG-treated oocytes stimulated the pump activity curtailed by the two latters. The impairment of Na⁺-K⁺ pump activity by diacylglycerols suggests that protein kinase C activators may stimulate endocytosis of membrane-coupled Na⁺-K⁺ ATPase.     

Goat erythrocyte calmodulin is not abnormal

Calmodulin was purified from goat erythrocyte hemolysate using heat treatment and Sephadex G-100 gel filtration chromatography. The molecular weight and Stokes, radius of the purified calmodulin was determined. The goat erythrocyte calmodulin stimulated (Ca(2+)-Mg2+)-ATPase but not (Mg2+)-ATPase and (Na(+)-K(+)-Mg2+)-ATPase. The (Ca(2+)-Mg2+)-ATPase of the erythrocyte membrane derived from human, rat, rabbit and pig were significantly stimulated.     

New structural features of the flagellar base in Salmonella typhimurium revealed by rapid-freeze electron microscopy.

The structure of the flagellar base in Salmonella typhimurium has been studied by rapid-freeze techniques. Freeze-substituted thin sections and freeze-etched replicas of cell envelope preparations have provided complementary information about the flagellar base. The flagellar base has a bell-shaped extension reaching as far as 50 nm into the bacterial cytoplasm. This structure can be recognized in intact bacteria but was studied in detail in cell envelopes, where some flagella lacking parts of the bell were helpful in understanding its substructure. Structural relationships may be inferred between this cytoplasmic component of the flagellum and the recently described flagellar intramembrane particle rings as well as the structures associated with the basal body in isolated, chemically fixed flagella.     

Interaction of Meloidogyne javanica with Different Races of Meloidogyne incognita

The interspecific interactions of Meloidogyne javanica with races 1, 2, 3, and 4 of M. incognita on tomato were determined. Impacts of the interactions on fecundity and morphometrics of females were also examined. Mutually inhibitory interactions occurred between M. javanica and the races of M. incognita, but the negative interactions did not reflect in plant growth. Numbers of root galls, egg masses, mature females, total population, fecundity, and reproduction factor declined in concomitant treatments, but the morphometrics of the females remained unaltered. In general, mutual suppressive effects in all parameters were smaller for M. javanica than M. incognita, but some variations occurred among the races of M. incognita. Race 2 appeared to be more competitive than other races. The interaction between the species was not intense; therefore, the species coexist in mixed populations in agricultural fields.     

Influence of reproductive organs on plant senescence in rice and wheat

The chlorophyll and protein contents of the flag, second and third leaves gradually decreased during the reproductive development of rice (Oryza sativa L. cv. Rasi) and wheat (Triticum aestivum L. cv. Sonalika) plants, whereas proline accumulation increased up to the grain maturation stage and slightly decreased thereafter. In rice plant, the rate of decrease in chlorophyll and protein and increase in proline level were higher in the flag leaf than in the second leaf. It was opposite in wheat plant. The export of [³²P]-phosphate from leaves to grains gradually increased reaching a maximal stage at the grain development stage, and then declined. The export of this radioisotope was greater in rice than in wheat. Removal of panicle at the anthesis and grainfilling stages delayed leaf senescence of rice plant, while in wheat the ponicle removal at any stage did not have a marked effect on delaying leaf senescence. The contents of chlorophyll and protein of glumes were higher in wheat than in rice. The variation of such source-sink relationship might be one of the possible reasons for the above effect on leaf senescence.