Behavioral Development and Parental Investment in Captive Bongos (Tragelaphus eurycerus)

SYNOPSIS. The bongo is one of the least-studied of the Tragelaphini.In a study of five captive bongo calves, two males and threefemales, we measured several behaviors important to parentalinvestment theory (Clutton-Brock et al., 1982), in order todescribe their pattern in a rare species, and add to the databasepertaining to sex allocation theory. Variations in individualpatterns of maternal investment, such as suckling rate and boutlength, were measured and graphed over time, with sex of calf,and age and dominance of dam indicated. Instances of "thiefsuckling" by calves and juveniles were also described in termsof kinship among the animals involved. Only one measure of maternalinvestment was biased in favor of males, which had a somewhathigher birth weight than females. Other measures showed littlesex difference. Among these calves, maternal care appeared tovary more with dominance and age of the dam than with sex ofcalf. Data from these animals generally conform more closelyto those of Byers and Moodie (1990). They found little evidenceof sex-biased investment among pronghorn (Antilocapra americana)fawns, and postulated that many ungulates have such a high rateof development that further differential investment is impossible.Robust biological theories are supported by data obtained froma wide variety of species, many of which are impossible to studyclosely in the wild. Additional studies on captive populationsof sexually dimorphic species would contribute usefully to theaccumulation of data pertinent to parental investment theory.     

Is suicide preventable

Among 500 cases of suicide analyzed in Stockholm, fewer than a third were associated with depression. Most forms of psychiatric disease were represented. Nevertheless, most persons give some warning before attempting suicide, and these warnings should be the signal for preventive action. Centers with trained personnel could prevent many suicides, if the potential victims were recognized and referred early enough. Laymen too should be educated to recognize potential suicide and help avert it.     

Specific Ribonucleoprotein Fragment from the 30S Subunit of <Emphasis Type="Italic">E. coli</Emphasis> Ribosomes

WE describe here a new approach to the determination of the three dimensional arrangement of the proteins within the ribosome, based on controlled degradation with nuclease. We suggest that by isolating ribonucleoprotein (RNP) fragments and determining which particular proteins each fragment contains, it should eventually be possible to construct a detailed “map” of the protein arrangement. The “mapping” problem has already received attention in various laboratories. Mizushima and Norrtura¹ have shown that the proteins of the E. coli 30S ribosomal subunit assemble with 16S RNA in a highly specific order. Further, the reactivity of the 30S particle towards proteolytic enzymes² and protein-modifying reagents³ shows a striking correlation with Mizushima and Nomura's “assembly map”¹, in that the first group of proteins in the assembly process seems to be protected in the completed particle.     

USE OF MINERALISED WATER BY KALAHARI WILDLIFE AND ITS EFFECTS ON HABITATS

This study surveyed the use made by springbok, hartebeest, wildebeest and gemsbok, in particular, of mineralised artificial waterholes along the Nossob river in the southern Kalahari and the effects of this use on the delicate surrounding habitats, as a basis for evaluating the uses and limitations of such water in the management of these species. Taking into account the chemical composition of the dissolved salts in the water; the status of the vegetation and conservation trends near water holes; the relative use made of the waterholes by the antelopes; and land use history, it was concluded that: (a) the animals made regular use of the water, some of which was more mineralised than that recommended for domestic stock, including sheep; (b) there was no relationship between the total dissolved salts and animal use, although there may have been some association between gemsbok use and certain ions; (c) wildlife attracted to boreholes had very little effect on the stability of some surrounding habitats, but may have retarded recovery in areas downgraded by past land use, and (d) under these circumstances the effects of this land use were still amply evident after 2¹/₂ decades. From this and other evidence, it is suggested that, at the present level of knowledge, mobile wildebeest populations can be stabilised by the provision of relatively potable water, and mineralised water may be used to raise the levels of springbok, hartebeest and gemsbok populations. However, as the water is less of a limiting factor than for species requiring regular drinking water, the increase in density may be relatively limited and so less of a danger to the maintenance of surrounding habitats.     

Effect of Waterlogged Soil Conditions on the Production of Ethylene and on Water Relationships in Tomato Plants

The roots of tomato plants (Lycopersicon esculentum Mill., cv.Moneymaker) were exposed to low concentrations of oxygen bywaterlogging the soil or by growing the plants in nutrient solutionflushed with nitrogen gas. After 24 h, the rate of ethyleneproduction by the petioles, main stem, and shoot apex was increasedby 4–6-fold and the petioles developed epinastic curvatures.Removing the roots did not reproduce these responses. The amountsof ethylene produced by shoot tissues in response to physicalwounding was greatly increased by waterlogging the soil. The production of ethylene by roots was suppressed by the absenceof oxygen. When the roots were transferred back to an aerobicenvironment ethylene production quickly exceeded that observedin roots maintained continuously in aerobic conditions. The enhanced rate of ethylene production in the shoots occurredin the absence of increased water stress as measured with aleaf pressure chamber; leaf water potentials were increasedrather than decreased by waterlogging for 30 h or more. Thiswas associated with stomatal closure and reduced transpiration.Resistance to water flow through the plant increased as transpirationdecreased in response to waterlogging. However, at similar ratesof transpiration, resistance was normally lower in waterloggedplants than in controls.     

Resuscitation of amebae deprived of essential symbiotes: Micrurgical studies*

SYNOPSIS. The effect of depletion and restoration of obligatory bacterial endosymbiotes on Amoeba proteus strain xD was studied. Removal of the symbiotes by culturing the amebae at 26.5 C resulted in loss of viability of the host cells, indicating that this strain is dependent on its endosymbiotes for survival. Amebae depleted of bacteria could initially be resuscitated by injection of isolated symbiotes, but prolonged deprivation led to irreversible changes. Nuclei of aposymbiotic amebae were viable when transplanted into the cytoplasm of normal cells, but the symbiote-depleted cytoplasm of heat-treated amebae could not be resuscitated by renucleation. No immediate ultrastructural changes were detected in aposymbiotic amebae except for clumping of nucleoli. Thus it appears that the symbiote performs an essential function as a cytoplasmic constituent.     

Towards a Non-Terminal Viability Assay for Foraminiferan Protists

ABSTRACT. Epifluorescence microscopy and spectrofluorimetry were investigated as possible non-terminal methods to distinguish live from dead foraminifera. Seven fluorogenic probes (diacetates of fluorescein [FDA], carboxyfluorescein, dichlorofluorescein, and carboxyeosin; AM-esters of biscarboxyethylcarboxyfluorescein [BCECF-AM], calcein, and calcein blue) were tested on Allogromia laticollaris . The probes that consistently produced the brightest fluorescence signals (BCECF-AM and FDA) were judged non-toxic to Allogromia , on the basis of short-term pseudopodial deployment and long-term reproduction assays. Once protocols were established, these two probes were tested on 13 additional benthic foraminiferal species. We found that BCECF-AM is the most suitable probe for direct epifluorescence microscopy of metabolically active foraminifera, especially tectinous and transparent calcareous species. Using spectrofluorimetry, FDA showed promise for opaque species because fluorescence is detected in the incubation media after its release from the cell. However, both approaches could only be used with confidence in light of appropriate controls established for each species examined.