An Efficient Regression Type Estimator in Survey Sampling

For the estimation of population mean in simple random sampling, an efficient regression-type estimator is proposed which is more efficient than the conventional regression estimator and hence than mean per unit estimator, ratio and product estimators and many other estimators proposed by various authors. Some numerical examples are included for illustration.     

The influence of zinc and sulphur deficiency on oil-filling in peanut (Arachis hypogaea L.) kernels

In the developing peanut (Arachis hypogaea L.) kernels, the period between 15 and 35 days after podding (DAP) was identified as the active period of oil-filling. The period of active oil-filling was associated with a decrease in the starch, soluble sugars and proteins so as to make available the energy and carbon skeleton for the synthesis of oil. The oil content in the mature kernels decreased by 11, 12 and 25 per cent with Zn, S and Zn+S deficiency, respectively. In addition, proteins and starch content decreased significantly while that of soluble sugars increased slightly. The activity of malate dehydrogenase and glucose-6-phosphate dehydrogenase also decreased due to Zn as well as S deficiency. The deficiency treatments resulted in a decrease in phospholipids, free fatty acids and triacylglycerols in mature kernels. Further the proportion of 16∶0 and 18∶2 decreased while that of 18∶1 increased in developing kernels.     

Conformations of peptides containing Z-alpha,beta-dehydroleucine (delta ZLeu). A comparison of Boc-Pro-delta ZLeu-Gly-NHEt and Boc-Pro-delta ZPhe-Gly-NHEt

Two tripeptides of the type Boc-Pro-delta ZX-Gly-NHEt (where X = Leu, Phe) have been synthesized and their solution conformations investigated by 270 MHz 1H n.m.r. and i.r. spectroscopy. These conformational studies indicated that delta ZLeu, similar to delta ZPhe, has a strong tendency to stabilize folded Type II beta-turn conformations when present at i + 2 position.     

Active transport of ATP and presence of a vanadate-sensitive membrane-bound ATPase in Mycobacterium leprae.

It is not known how Mycobacterium leprae obtains energy for survival and growth in the host tissues; the organism does not grow in vitro. In the studies reported here, M. leprae incorporated labelled ATP, which was blocked by cyanide, unlabelled ATP or ADP, but not by adenosine or Pi. It seems that the organism takes up unhydrolysed ATP by an active transport process. The bacterium contained a membrane-bound, vanadate-sensitive E1 E2-ATPase (which creates a transmembrane potential driving transport of solutes into cells). The enzyme was not inhibited by N-ethylmaleimide, suggesting that it is not an F0F1-ATPase which catalyses ATP synthesis. Apparently, M. leprae derives energy-rich compounds from the host cell.     

Circadian variation in migration velocity in small intestinal epithelium

The variation in migration rates of cells within the small intestinal epithelium was studied over a 24-hr period at 3-hr intervals (migration of cells was studied independently for the crypts and the villi using the changing distributions of [3H]TdR labelled cells as an indicator of cell migration). Clear changes in the rates of cell movement were observed during a 24-hr period for both crypt and villus epithelium. The rates of cell migration in these two compartments did not correlate well with the exception of samples taken at 18.00 hours. At this time of day there appeared to be no cell movement at all in either crypts or villi. There was not a good correlation between the migration velocity throughout the day and the changes in the number of mitoses. It is proposed that mitotic rates do not directly govern migration rates but that the converse may be true. Further, the lack of correlation between crypt and villus migration rates at any time of day suggest that the mechanisms controlling all movement in these two regions of small intestinal epithelium may be different.     

Labelling of amoeboid microglial cells in rats of various ages following an intravenous injection of horseradish peroxidase

The macrophagic amoeboid microglial cells in the corpus callosum of postnatal rats were labelled following an intravenous injection of horseradish peroxidase (HRP). The earliest time when these cells were labelled was 3 h after the injection of HRP in postnatal (1-10 days) rats. Similar cells around the mesencephalic aqueduct and the fourth ventricle were also labelled. These cells, however, were weakly labelled in developing (11-20 days) and unlabelled in weaning (21-30 days) rats. The results suggest that in the postnatal rats, the HRP passed through the endothelial lining of the blood vessels and was then ingested by the amoeboid microglial cells. In the developing and older rats, the wall of blood vessels had developed fully thereby preventing the free passage of HRP into the brain tissues.     

Survival and growth of Bacillus cereus in bread

Bread doughs were artificially inoculated with spores of six Bacillus cereus strains at different inoculum levels and counts of survivors in bread determined during storage at 27.5 degrees C. No B. cereus were isolated from the centre crumb of 400 g loaves when the dough contained less than 10(4) spores/g whereas with 800 g loaves survival occurred with doughs containing 5.0 X 10(3) spores/g. With all strains there was a period of at least 24 h before multiplication took place in the bread. The inclusion in dough of 0.2% of calcium propionate, based on flour, effectively delayed germination and subsequent multiplication of B. cereus spores. It is concluded that the risk of food poisoning due to the presence of B. cereus in bread is minimal.     

Genetics of yellow berry in wheat (Triticum aestivum)

Summary The inheritance of yellow berry, a grain disorder in durum and bread wheats, was studied in six intervarietal crosses in bread wheat. The trait was found to be controlled by either two or three dominant genes. Monosomic analysis using Chinese Spring monosomic series showed the presence of two major dominant genes on chromosomes 1A and 7A, and four modifiers on 4A, 4B, 6A and 6D, which influence the expression of yellow berry in bread wheat.