Studies on the properties of the variants of gamma-glutamyl transpeptidase in human urine

Both the high molecular weight and the low molecular weight variants of urinary Y-glutamyl transpeptidase, displayed transpeptidase (pH optimum 8.6) and autotrans-peptidase (pH optimum 9.4) activities. Iodoacetamide inhibited the transpeptidase activity more efficiently than the autotranspeptidase activity with respect to both variants of Y-glutamyl transpeptidase. The high molecular weight form utilized L-glutamine as a better acceptor than L-cystine during the transpeptidation reaction whereas the reverse was the case with the low molecular weight variant. While phenylmethylsulphonyl fluoride-treated enzymes retained full activitiesper se, addition of maleic acid to the modified enzyme was found to inhibit the catalytic activities indicating a maleic acid-induced conformational change of the modified enzyme.     

The ecology of marine exploitation in prehistoric Hawaii

Archaeological evidence for prehistoric strategies of marine exploitation in Oceania may be profitably analyzed from an ecological perspective, in which individual sites and assemblages are viewed in the context of adaptation to local environmental constraints. This perspective is illustrated through the contrastive analysis of environment, technology, and faunal remains at three prehistoric Hawaiian sites. Differing strategies of marine exploitation evidenced for each site are shown to reflect local marine environmental conditions. An ecological approach shows greater promise for an understanding of prehistoric adaptation to marine environment than the typological analyses current in much archaeological work on fishing.     

Restriction fragment maps of the genome of Bacillus subtilis bacteriophage SPβ

Six different restriction endonucleases were used to generate restriction fragment maps of the genome of the temperate Bacillus subtilis phage SPβ. AvaI and SalI each had six target sites in the phage DNA, AvaII had three, BamHI had seven, PstI had twenty, and SacI had sixteen. Restriction analysis and heteroduplex analysis were used to locate a 10-kb region of DNA that is deleted in the clear-plaque mutant, spβci. Thedeletion lay approx. 50 kb from the left end of the 126-kb phage genome.     

Strontium and diet at Hayonim Cave

Faunal and human bones from the Natufian and Aurignacian levels of Hayonim Cave, Israel, were analyzed for calcium, strontium, and phosphate, in order to investigate the efficacy of strontium measurements for determining the proportion of meat in human diets. This site in the western Galilee was appropriate for a test of the technique since a)herbivore and carnivore fauna were present in numbers from two different time periods, b) well-characterized human skeletons were also present in at least one of these levels, and c)the diets of the individuals examined were basically well understood. On the basis of Sr/Ca values, a large difference was observed between Natufian herbivore bones and carnivore bones in the manner predicted by the diets of these species. Sr/Ca values for the adult humans from the same level fell midway between the herbivore and carnivore ranges. However, a different pattern was observed for Aurignacian fauna; no difference could be found between Sr/Ca ratios of herbivore and carnivore bones. The findings suggest that, in certain circumstances, the technique may provide important new paleodietary information. However, at any given site or level, both herbivore and carnivore fauna should be analyzed before conclusions about human diets are drawn from it.     

The fractionation of iron-phosphorus compounds in sediments studied by Mössbauer spectroscopy

Iron compounds of phosphorus form a large part of the phosphorus bound in sediments. Mössbauer spectroscopy is a technique that enables us to study, directly, chemical forms of iron in solid samples. Mössbauer spectroscopy allowed us to check, directly, the selectivity of the extraction scheme for soil phosphorus proposed by Chang &; Jackson (1957), but only as far as the iron compounds are concerned. It appears that selectivity of the extraction method leaves much to be desired.

     

Correlation of rotifer associations in a chain of lakes fed by reclaimed sewage

The quantitative composition of the rotifer fauna of seven interconnected lakes located in southern California was studied in a preliminary investigation. The lakes are fed by reclaimed sewage, and the water quality increases rapidly from the first lake, barely able to support life, to a series of lovely lakes stocked with fish and utilized for recreation. The Shannon index of rotifer population diversity showed an appropriate increase. Up to 24 – 28 different rotifer taxa in each lake provided a rich community dominated by Brachionids, Keratella and Trichocerca. The diversity and quantity of the rotifer association then declined again in the last lake. Comparison of the lakes using the Bray and Curtis index of similarity and cluster analysis supported the picture of a lake-chain evolution, a biotic development showing a maximum curve.     

Late quaternary dynamics of pollen influx at mineral lake,Washington

Pollen influx analysis at Mineral Lake, Washington, indicates that immediately south of the Puget Lobe of the Fraser Glaciation, tundra was a characteristic vegetation until 16,300 years ago. Invasion ofPinus contorta began 17,500 years B.P., and boreal climax conifers (Abies, Picea andTsuga mertensiana), 16,300, but was temporarily interrupted by the Vashon advance (14,500–14,000 yr B.P.).Pseudotsuga menziesii began to grow in population 10,750 years ago, and woodland was established within a time span of 1,000 years. Modern lowland coniferous forests began to form 7,000 years ago. Logistic analysis of pollen abundance changes show that the intrinsic growth rate,r (yr⁻¹), of pioneer species (e.g. 0.024–0.026 inPteridium aquilinum) is higher than that of climax species (e.g. 0.003 inThuja plicata).P. menziesii, a subclimax species, shows an intermediater value (0.013) between these two ecologically different taxa. The absoluter value ofP. contorta (−0.011) is only slightly lower than that ofP. menziesii, although their replacement began almost simultaneously. Thus competition between these species was intense before the inflection point ofPinus curve 10,100 years ago. At this time, forest gaps became abundantly available forPseudotsuga, as indicated by a peak of the diagnostic factor (the reciprocal of the pollen influx).