Bacterial Characteristics Determining the Potential Host Range of Bacteriophage T4

Many members of the Enterobacteriaceae, but not other gram-negative organisms, apparently carry a specific recognition site for the T4 tail tube on their cytoplasmic membranes.     

Dissociation and reassociation of rabbit skeletal muscle myosin

Whereas dissociation of rabbit skeletal muscle myosin light chains occurs at an increased temperature (25°) and in the obsence of divalent cations, reassociation of the myosin oligomer requires a low temperature (4°C) and the presence of divalent cations, thus resulting in the original light to heavy chain stoichiometry. With a 5–10 per cent release of alkali light chains, LC₁ and LC₃, and a 50 per cent dissociation of the Ca²⁺ binding light chain, LC₂, there is no significant decrease in myosin ATPase activity irrespective of the cation activator, however, there is an approximate 15–20 per cent decrease in actomyosin ATPase activity. With reassociation of the myosin oligomer, actomyosin ATPase activity is partially restored as well as the original number of Ca²⁺ binding sites.     

Potassium Depletion in Severe Heart Disease

Exchangeable sodium and potassium, total body water, and sulphate space were measured in 42 patients with severe valvular heart disease who were free of oedema. Compared with normal subjects of the same height, no increase in exchangeable sodium was found but a mean potassium depletion of 27% was shown. This depletion was not related to diuretic therapy, and no relationship between the degree of depletion and postoperative arrhythmias was found. It is concluded that the major cause of the low exchangeable potassium is the reduction in cell mass that occurs in chronic heart disease, and that there is no significant fall in the intracellular potassium concentration.     

Social mechanisms of population regulation in a captive group of bonnet macaques (Macaca radiata)

The purpose of the present paper is to evaluate the factors that contributed to annual variation in fertility and infant survival in a relatively undisturbed captive group of bonnet macaques (Macaca radiata) over a 16-year period. The size and composition of this population fluctuated over time, and these changes were consistently associated with changes in female fertility and infant survival. Female fertility was highest when there were relatively few adult females in the group and when there were relatively few adult females per adult male. Similarly, infant survival was highest in years when there were relatively few adult females present and when cohorts of infants were small. Since environmental factors, such as availability of food and vulnerability to predation, were unlikely to constrain population growth in captivity, the data suggest that other mechanisms may have affected demographic processes in this captive group.     

Population structure of Leptothorax ambiguus,a facultatively polygynous and polydomous ant species

We examined the genetic and spatial structure of Leptothorax ambiguus in a Vermont site. Nests of this tiny ant species have variable queen number and comprise larger polydomous colonies, as do their closest relatives in North America. Nests are patchily distributed in the forest, and sometimes occur in local abundance. We collected 121 nests in four years from plots in which all nests were mapped; furthermore, we subjected nests collected in two separate years to starch gel electrophoresis and estimated relatedness according to the Queller—Goodnight (1989) algorithm. Queens that share a nest site also share 33% of their alleles on average, and relatedness among worker nestmates is about 0.5. The existence of diploid males and nonzero F-values demonstrate inbreeding in this species, an unusual phenomenon for social insects in general. Mapping data showed that nests with like genotypes tended to cluster in space, forming polydomous colonies. Colonies consisted of 1–6 nest subunits, and about half of all colonies were polygynous. We compare these features of L. ambiguus to its close relative L. longispinosus and a European congener L. acervorum. These comparisons allow us to conclude that an interplay between ecological and genetic factors produces the observed pattern of multiple queening and nest spatial distribution in this species.     

Kidnapping and female competition among captive bonnet macaques

Rank, parity, and kinship influence the pattern and frequency of kidnapping interactions in a group of captive bonnet macaques,Macaca radiata. Kidnapping attempts are initiated by parous and nulliparous females toward the infants of lower ranking females. Contrary to the pattern documented in several other species, nulliparous females participate in kidnapping interactions at the same rate as lactating females. Kidnapping attempts are consistently resisted by mothers, and most attempts are unsuccessful. Both the rates and pattern of kidnapping interactions differ within and between lineages. The results suggest that kidnappers gain neither status nor maternal experience and that the mothers of kidnapped infants do not benefit at all. Kidnapping may represent a form of competition among females which is detrimental to both infants and their mothers.     

Central nervous system antigen (NS-5) and its presence during murine ontogenesis

An antiserum raised by immunization of C3H.SW/Sn mice with cerebellum from 4-day-old C57BL/6J mice recognizes a cell surface component(s) [NS-5] present in different degrees on various parts of the mouse central nervous system. When analyzed by an antiserum-and complement-mediated cell cytotoxicity test and by the ability of various tissues to absorb anti-NS-5 antiserum activity, the antigen(s) was detectable on cerebellum, retina, olfactory bulb, cortex, basal ganglia, and medulla, but not on nonneural tissues with the exception of mature spermatozoa and 4-day-old kidney. The antigen(s) detected by the anti-NS-5 antiserum was found in similar quantities on young and adult rat and mouse cerebellum; however, it was not detectable on any of 16 clonal cell lines derived from the rat central nervous system. During preimplantation stages of murine development, the antigen could be detected on all cells of (2–4)-cell and (8–16)-cell stages and on the trophoblastic cells of blastocysts by indirect immunoflourescence. Embryos on day 9 of gestation, the earliest stage tested after implantation, expressed the antigen(s), but expression was restricted to the nervous system.     

The role of superoxide radical in the autoxidation of cytochrome c.

The net rate of autoxidation of ferrocytochrome c was decreased by ferricytochrome c. Superoxide dismutase accelerated this autoxidation to a limit and overcame the inhibitory effect of ferricytochrome c. This was the case whether the autoxidationwas observed in the presence or in the absence of denaturants, such as alcohols orurea, and whether the superoxide dismutase used was the Cu-2+-Zn-2+ enzyme from bovine erythrocytes or the Mn-3+-enzyme from Escherichia coli. It can be deduced that the autoxidation of ferrocytochrome c, under a variety of conditions, geenerates O2 minus which can then dismute to H202 + O2 or can reduce ferricytochrome c back to ferrocytochrome c. Superoxide dismutase, by accelerating the dismutation of O2 minus, prevents the back reaction and thus exposes the true rate of reaction of ferrocytochrome c with molecular oxygen.