Location of the active site of the bean {alpha}-amylase inhibitor and involvement of a Trp, Arg, Tyr triad

Seeds of the common bean contain three homologous proteins:phytohaemagglutinin E, phytohaemagglutinin L and the lectin-likeprotein     

A genetic component in human lysosomal enzyme excretion

Acid hydrolases are present in normal human urine in appreciable amounts. Their source appears to be lysosomes released by kidney proximal tubule epithelial cells. For a given lysosomal enzyme the total amount excreted is the product of two parameters, a general one describing the rate of lysosome secretion and a specific one describing the relative concentration of that enzyme in lysosomes. There is considerable population variation in both parameters. Studies of -glucuronidase, -galactosidase, -hexosaminidase, and -galactosidase in monozygotic and dizygotic twins show that an appreciable part of this variation is genetic in origin. This appears to be true for both total enzyme excretion and lysosome composition. Although it was not possible to test directly whether this is also true for the rate of lysosome secretion, the fact that the two former parameters are both heritable strongly suggests that the rate of lysosome excretion is also a heritable trait. Taken together with previous data, the results suggest polygenic control of these biochemical traits. It is particularly significant that -glucuronidase excretion in normal individuals is a heritable trait since the excretion of this enzyme has frequently been used as a measure of normal and pathological physiological changes.This study was supported by grants from the National Institutes of Health (GM-19521) and the Council for Tobacco Research—U.S.A., Inc. (1080). The work was done while the authors were in the Department of Molecular Biology, Roswell Park Memorial Institute, Buffalo, New York 14263.     

Nile water as a cause of Eastern Mediterranean sapropel formation: Evidence for and against

During the late Pleistocene, sapropels (layers of organic-carbon rich sediment) formed throughout the entire Eastern Mediterranean Basin in close association with glacial/interglacial transitions. The current theory for the mechanism of sapropel formation involves a density stratification of the water column, due to the invasion of a large quantity of low-saline water, which resulted in oxygen depletion of the bottom waters. Most workers believe that this low-salinity water was glacial meltwater that entered the Mediterranean via the Black Sea and a series of interconnected glacial lakes, but the suggestion also has been made that the freshwater originated from the Nile River. In this study the oxygen isotope values of planktonic foraminifera,Globigerinoides ruber, have been examined in six gravity cores and one piston core from the southern Levantine Basin, and compared with the oxygen isotope records ofG. ruber from other areas of the Eastern Mediterranean. This study deals mainly with the latest sapropel which was deposited approximately 7000 to 9000 years ago. Results indicate that Nile discharge probably does reduce salinities somewhat in the immediate area surrounding the mouth of the Nile, but this water is rapidly mixed with the highly saline waters of the easternmost Mediterranean.Using a mixing equation and surface water salinity limitations, an approximate oxygen isotope balance of surface waters was calculated for the time of latest sapropel deposition. This calculation shows that neither Nile River discharge nor Black Sea input (nor both together) are large enough to account for the large-scale oxygen isotope depletion associated with latest sapropel deposition in the Eastern Mediterranean. This suggests that part of the isotopic change at Termination I is probably due to increased surface water salinities during the last glacial maximum. In addition, evidence from the timing of sapropel 1 deposition and the dissolved oxygen balance indicates that deposition of the latest sapropel is associated with increased surface water production of biogenic material, as much as three times higher than that of present day.     

Inversions and other unusual heteromorphisms detected by C-banding

Summary Sixteen patients with unusual heteromorphisms involving alterations of the length and/or position of centromeric heterochromatin are described. Family studies showed that the heteromorphisms were present in other relatives and segregated in the expected 1:1 ratio. There was a significantly greater frequency of unusual heteromorphisms among Orientals than in other races studied.     

Regulation of the synthesis of human chorionic gonadotropin by strains of HeLa cells in culture

Summary Thirty-seven strains of HeLa cells were examined for their ability to synthesize human chorionic gonadotropin (hCG) and its alpha subunit (hCG-α) in culture. Synthesis of hCG-α and hCG also was investigated in the presence of sodium butyrate and 5-bromo-2′-deoxyuridine (BrdUrd). All HeLa strains synthesized hCG-α in culture. Sodium butyrate increased the synthesis of hCG-α in all HeLa cells; BrdUrd increased synthesis in 32 of the 37 strains examined. Although few HeLa strains synthesized hCG in the absence of inducers, hCG was detected in most strains in the presence of sodium butyrate. The synthesis of hCG and its alpha subunit is, therefore, a stable genetic characteristics of HeLa cells. Certain preparations of hCG and its subunits were generously provided through the Center for Population Research of the National Institute of Child Health and Human Development, NIH.     

Competitive interactions and the availability of sleeping sites for a diurnal coral reef fish

A field study was made to test whether the population size of a diurnal reef fish, the wrasse Thalassoma bifasciatum (Bloch), was limited by inter- or intraspecific competition for sleeping shelter. T. bifasciatum is often attacked at dusk by two small territorial damselfishes, Eupomacentrus dorsopunicans (Poey) and E. planifrons (Cuvier). Although these three species sleep in the same general habitats, there are qualitative differences in the types of holes they use and how they use them. Wrasse holes are usually in these damselfishes' territories, but damselfish attacks do not prevent wrasses entering holes. Wrasses infrequently defend their holes intraspecifically. They regularly change their holes, with little intra- or interspecific aggressive interaction. When its hole is removed, a wrasse is late in retiring but finds a hole near its old one with little aggressive interaction, and does not have a higher mortality rate. Empty wrasse holes are rarely refilled, and then only by conspecifics. Wrasses added to reefs find unoccupied holes and do not usurp other fishes' holes. Damselfish defend their eggs and food against the wrasse, but not their sleeping shelter, nor living space per se. Sleeping sites are not limiting the wrasse, but are present in a surplus. Intraspecific hole defense by a wrasse prevents a delay in its retiring that would increase the risk of crepuscular predation on it.     

Daytime births in captive patas monkeys

Daytime births in two patas colonies were the rule rather than the exception.     

Induction of placental alkaline phosphatase in choriocarcinoma cells by 5-bromo-2′-deoxyuridine

Summary Growth of choriocarcinoma cells in the presence of 5-bromo-2′-deoxyuridine (BrdUrd) results in a 30- to 40-fold increase in alkaline phosphatase activity. The effect of BrdUrd is specific for phosphatase with an alkaline pH optimum. The induction by BrdUrd is probably not due to the production of an altered enzyme, since the induced enzyme resembles the basal enzyme in thermal denaturation and kinetic properties. Enzyme induction can be prevented by thymidine but not by deoxycytidine or deoxyuridine. The induction of alkaline phosphatase appears to require incorporation of the BrdUrd into cellular DNA. The presence of BrdUrd in the growth medium is not necessary for alkaline phosphatase induction in proliferating cells containing: BrdUrd-substituted genomes. However, enzyme induction and maintenance of the induced levels of alkaline phosphatase in nonproliferating cells containing BrdUrd-substituted DNA requires the presence of the analogues in the medium. The induction of alkaline phosphatase by BrdUrd in probably an indirect process.     

An inhibition enzyme immunoassay for myelin basic protein

An improved Enzyme Immunoassay for Myelin Basic Protein is described. Myelin Basic Protein covalently attached to glass balls, and Myelin Basic Protein in samples compete with each other for binding of a peroxidase conjugated anti Myelin Basic Protein antibody. The peroxidase activity on the balls is then inversely proportional to the amount of Myelin Basic Protein in the sample. A detection limit of 0.6 ng/ml is demonstrated for diluent or spinal fluid. For plasma a dilution step increases this to 1.8 ng/ml. Both the coated balls and the peroxidase conjugate are stable for long periods. The assay requires no expensive equipment. Although the assay appears to be valid for subcellular fractions spinal fluid and plasma, successful detection of Myelin Basic Protection peptides in clinical samples may require careful selection of suitable antisera. The assay would be very suitable for eventual use with an appropriate monoclonal antibody.     

The influence of nearest neighbors on the rate and pattern of spontaneous point mutations

Summary The numbers and local sequence environments of the two types of substitution mutation plus additions and deletions have been obtained directly in this study from differences between a large number of extant primate gene and pseudogene sequences. A total of 3786 mutations were scored in regions where similarities between pseudogene and corresponding gene sequences is 85%, comprising 30% of the pseudogene database of 80,584 bp. The pattern of mutations obtained in this fashion is almost identical to that obtained by Li et al. (1984) using a slightly different, more direct approach and with a smaller database. When mutations were scored, the neighbor pairs on the 5 and 3 sides were also noted, leading to a large 16 × 12 matrix of transitions and transversions. Biases of varying magnitude are found in the rates of substitution of the same base pair in different local sequence environments. The overall order for the effect of the 5 neighbor on the rates of substitution mutation of a pyrimidine is A > C T > G, and G > A > T > C for the 3 neighbor; where these results represent the average of substitution rates for the complement purine with complement neighbors of bases ordered above. The order for the 3 neighbor is essentially the same for the two transitions and most of the four transversions as well; however, the order for the 5 neighbor is more variable. The overall rate for the C · G T · A transition is not unusual, however the presence of a 3 neighboring G · C pair boosts the rate substantially, presumably due to specific cytosine methylation of the CG doublet in primate DNAs. The rate of the T · A C · G transition is also well above average when the 3 neighbor is an A · T, and to a lesser extent a G · C, pair. The latter bias is typical in that it reflects the association of alternating pyrimidine-purine sequences with increasing mutation rates. The substitution of the pyrimidine in a 5 purine-pyrimi-dine-purine3 sequence generally occurs much faster than in a pyrimidine tract and points to the local conformation as a major determining factor of the substitution rate. An apparent inverse relationship is found between starting and product doublet frequencies of base pairs undergoing mutations with specific 3 neighbors, indicating that differences in intrinsic substitution rates of base pairs with specific neighbors are a key factor in producing the familiar biases of nearest-neighbor frequencies.Offprint requests to: R. D. Blake