Molecular genetics of cell death in the nematode Caenorhabditis elegans

In C. elegans, cell death can be readily studied at the cellular, genetic, and molecular levels. Two types of death have been characterized in this nematode: (1) programmed cell death, which occurs as a normal component in development; and (2) pathological cell death which occurs aberrantly as a consequence of mutation. Analysis of mutations that disrupt programmed cell death in various ways has defined a genetic pathway for programmed cell death which includes genes that perform such functions as the determination of which cells die, the execution of cell death, the engulfment of cell corpses, and the digestion of DNA from dead cells. Molecular analysis is providing insightinto the nature of the molecules that function in these aspects of programmed cell death. Characterization of some genes that mutate to induce abnormal cell death has defined a novel gene family called degenerins that encode putative membrane proteins. Dominant alleles of at least two degenerin genes, mec-4 and deg-1, can cause cellular swelling and late onset neurodegeneration of specific groups of cells. © 1992 John Wiley & Sons, Inc.     

A phylogenetic analysis of species in the Bufo crucifer group (Anura: Bufonidae), based on indolealkylamines and proteins from skin secretions

This research tested the utility of two classes of skin secretion compounds to the phylogeny of the Bufo crucifer group. Skin secretions from specimens of nine populations of B. crucifer group were obtained and submitted to qualitative analysis. We observed a clear difference in the composition of the skin secretion molecules obtained from the species of Bufo studied. Fifty-nine molecules, 16 indolealkylamines and 43 proteins, were used as characters, and 39 of these were parsimonious informative. The tree topology of the skin secretion combined data showed areas of congruence and conflict when compared to an mtDNA phylogeny of the B. crucifer group. We used the Templeton test to evaluate the heterogeneity between the skin secretion and mtDNA data. Although not recommended, we performed a combined analysis with the two partitions. The skin secretion characters from the species of Bufo studied have phylogenetic signal. These data are indicative, at least as a preliminary study, of the phylogenetic relationships among the B. crucifer group taxa.     

Winged leaf-cutting ants on nuptial flights used as transport by Attacobius spiders for dispersal

Abstract.  1. Sexuals of a leaf-cutting ant, Atta bisphaerica Forel, left their nest for nuptial flights in October to December.
2. When leaving a nest, 53 of the 479 winged sexuals (or alates) observed (11.1%) carried up to three inquiline spiders of Attacobius luederwaldti .
3. Spiders exclusively selected winged sexuals, not workers, and preferred females, indicating their expectation of the stronger flight ability of females. Neither these sexuals nor workers that appeared out of the nest on flight days attempted to remove or attack spiders on the body of alates.
4. New qucens landing from their nuptial flight did not carry spiders, indicating that the spiders had left the ants in the sky to be dispersed by wind.
5. No spiders were found in more than 100 incipient nests, which were estimated to be 2–3 months old. This suggests that the spiders jumped off the alate during mid-flight and dispersed on the wind to inhabit larger nests.     

Ecology and community dynamics of Kubo people in the tropical lowlands of Papua New Guinea

Kubo producer-units (families and independent bachelors) could have been self-sufficient in the production of bananas but chose not to be. Nor did they seek self-sufficiency in the production of any combination of staple carbohydrate foods (bananas, tubers, sago flour) or, in the long term, strive for balance in the exchange of food with other producer-units. Despite the fact that bananas, which provided 50% of people's energy needs, were a delayed-return crop Kubo communities were very unstable. This instability and the failure to choose the option of self-sufficiency were connected and were mediated through intense intracommunity sharing that, ultimately, served to negotiate a concern with sorcery. The people grew bananas in the way they did, not out of environmental necessity, but to accommodate the crop to the needs of sharing and, thereby, facilitate community living.     

Calling song and selective phonotaxis in the field crickets,Gryllus firmus andG. pennsylvanicus (Orthoptera: Gryllidae)

The field cricket species, Gryllus firmusand G. pennsylvanicus,occur in a mosaic hybrid zone that roughly parallels the eastern slope of the Appalachian mountains in the northeastern United States. It is important to know what role, if any, the calling song plays in mate choice in sympatric and allopatric populations. In this report, we present results on the variability of calling song properties along transects across this hybrid zone. We also present the results of experiments on phonotactic selectivity of females from an allopatric population of G. firmus.The male calling song of allopatric G. firmuswas significantly slower in temporal rhythm (i. e., chirp and pulse repetition rates) and lower in pitch (i.e., dominant frequency) than that of allopatric G. pennsylvanicus.Calling song properties of males recorded in the hybrid zone varied considerably in temporal and spectral properties. In two-stimulus (choice) phonotaxis experiments, allopatric females of G. firmuspreferred synthetic calling songs with conspecific pulse repetition rates over songs that had lower and higher pulse rates. This preference persisted even when the sound pressure levels of alternative stimuli were unequal. Therefore, allopatric females of G. firmuscan discriminate between conspecific and heterospecific calling songs. Whether or not this same selectivity is present in sympatric populations remains unclear. Investigations of phonotactic selectivity in other allopatric and sympatric populations of both species are currently under way.     

Expression by human fetal organs of organ-specific cancer neoantigens as measured by leukocyte adherence inhibition

Summary Human cancers express organ-specific cancer neoantigens (OSN) as determined by in vitro leukocyte responses to extracts of cancers by the tumor host. In this study, we determined whether the OSNs were normal developmental proteins that were expressed by fetal organs and re-expressed with oncogenesis. Fetal extracts, principally of lung and colon but also of liver and kidney, were tested for their ability to induce leukocyte adherence inhibition (LAI) as compared to extracts from adult tissues of the same organ. Leukocytes from lung cancer patients showed positive LAI responses to 13- and 19-week fetal lung tissue. Likewise, leukocytes from colon cancer patients showed positive LAI responses to 14- and 19-week fetal colon tissue, whereas leukocytes from control subjects did not. Neither group responded positively to 21-week fetal organs. Criss-cross experiments showed that the fetal antigen was organ specific. Multiparous pregnant women showed positive LAI responses to cancer extracts but not to extracts from normal tissues of the same organ. The pattern of the LAI response was bell-shaped. Positive LAI responses to lung and breast cancer were detected at 4 to 7 months gestation and peaked at 5 months. To the fetal colon, LAI positive responses were detected at 5 to 8 months gestation, with the peak response at 6 months. The results indicate that OSN of cancers are also expressed by fetal organs and sufficient antigen is shed by fetal organs to sensitize pregnant women. Older fetal organs (21 weeks) and adult organs do not express an immunogenic or antigenic OSN.Supported by a grant from the National Cancer Institute of Canada     

Multiple attractors,catastrophes and chaos in seasonally perturbed predator-prey communities

A classical predator-prey model is considered in this paper with reference to the case of periodically varying parameters. Six elementary seasonality mechanisms are identified and analysed in detail by means of a continuation technique producing complete bifurcation diagrams. The results show that each elementary mechanism can give rise to multiple attractors and that catastrophic transitions can occur when suitable parameters are slightly changed. Moreover, the two classical routes to chaos, namely, torus destruction and cascade of period doublings, are numerically detected. Since in the case of constant parameters the model cannot have multiple attractors, catastrophes and chaos, the results support the conjecture that seasons can very easily give rise to complex populations dynamics.     

Influences of habitat features and human disturbance on use of breeding sites by a declining population of southern fur seals (Arctocephalus australis)

Southern fur seals Arctocephalus australis in Peru have declined gradually over the past decade, and declined dramatically (72%) as a result of low food availability during the severe El Niño in 1997–98. In 1999, seals abandoned some historically important breeding sites. This is particularly alarming because new sites were not colonized. Our objective was to examine how habitat features and human disturbance influenced whether sites were currently used, abandoned or apparently not used in the past by fur seals for breeding. Data were collected on 14 variables at 70 potential breeding sites at three guano reserves in Peru. Discriminant analysis revealed significant multivariate differences among sites currently used for breeding, abandoned sites and unused sites ( F =5.97, P <0.00001), and the model classified 74% of sites correctly. Currently used sites were less likely to have human disturbance and more likely to have offshore islands, stacked rocks, tide pools and abundant shade. Separate discriminant analyses for each reserve produced similar results. Habitat associated with thermoregulation (e.g. shade or pools) may be more important to fur seals in Peru, which breed at lower latitudes and are at greater risk of overheating on land than other populations. Habitat with minimized human access may be especially important to seals in small populations in which individuals may perceive themselves as more vulnerable because of decreased vigilance and dilution effects. Seals in our study selected breeding habitat with stacked rocks, which create shade and tide pools for thermoregulation and make human access difficult; but pups might suffer higher mortality in this habitat. We hypothesize that fur seals in Peru may exhibit an Allee effect, whereby suitability of habitat varies with population abundance.     

The synthesis of S-(3-aminopropyl)thiosulfuric acid

In order to investigate the metabolism in vivo of homocystamine we needed the corresponding -SSO3H derivative and we attempted to prepare it. In this paper details are reported for the synthesis of S-(3-Aminopropyl)-thiosulfuric acid from 3-Bromopropylamine or thiosulfate. Same analytical date and chromatographic properties one also reported, which allow its identification.