Technical and theoretical considerations in the HLA typing of amniotic fluid cells for prenatal diagnosis and paternity testing

HLA typing of amniotic fluid cells has been used for the prenatal diagnosis of the HLA linked diseases congenital adrenal hyperplasia (21-OH-deficiency (21-OH-def) type) and complement C4 deficiency and it has also been used for the prenatal de termination of paternity. There are, however, technical difficulties in this test associated with the weak expression of some B locus antigens on amniotic fluid cells, and theoretical difficulties related to associations between particular HLA antigens and the 21-OH-def allele. Since certain HLA-B locus antigens are found in significantly increased frequencies among patients with 21-OH-def, there is a relatively high incidence of HLA-B homozygosity among the patients and over 40 percent of the parents of these patients share one or more HLA-B locus antigens. Results of some prenatal HLA typing tests may thus be difficult to interpret, and supplementary tests should be used whenever possible. HLA typing of amniotic cells is, however, the only available procedure for prenatal diagnosis of C4 deficiency and it is the best available procedure for prenatal determination of paternity. A modification of our original procedure allows HLA typing to be performed with increased numbers of HLA typing sera, and sera with optimum reactivity for amniotic fluid cells have now been selected for the definition of most of the more commonly expressed HLA antigens. Although amniotic fluid cells do not express DR antigens, amniotic fluid cells can be typed for the HLA-linked marker glyoxalase I (GLO) and this may be the informative for prenatal diagnosis in some cases.     

Age determination and growth of the bonnethead shark Sphyrna tiburo: a comparison of two populations

From July 1982 to December 1986, a study of the age and growth of the bonnethead shark Sphyrna tiburo was conducted in Tampa and Florida Bays, Florida, USA. Tetracycline-injected sharks held in captivity and, to a lesser extent, tagged, released and recaptured, were utilized for validating the annual nature of the rings (herein defined as the narrow, translucent regions) appearing on vertebral centra. The technique was validated for all age groups (0 to 6+yr) included in the study. Marginal increment analysis likewise suggested annual ring formation. The rings formed during the winter, when water temperatures were lowest. Using the vertebral ring aging-technique, von Bertalanffy growth curves for males and females from both tampa and Florida Bays were constructed. Growth of sharks born and held in captivity demonstrated that the male and female growth curves diverge after 1 yr and that mean sizes at age are statistically distinct after 2 yr. In both populations, females grew to larger sizes tha males and apparently are longer-lived. Reproductively mature females from Tampa Bay were significantly larger than those from Florida Bay.     

Relictual Amphibians and Old-Growth Forests

Abstract: Terrestrial and aquatic herpetofauna were sampled by pitfall traps, time-constrained searches, and area-constrained searches (stream sites only) over a three-year period to examine the importance of forest age to amphibians and reptiles. Fifty-four terrestrial and 39 aquatic sites in Douglas-fir—dominated, mixed evergreen forests were located in southwestern Oregon and northwestern California Mean age of trees on sites ranged in age from 30 to 560 years. Thirty-one species of amphibians and reptiles were detected from the 93 localities. Only three species were found primarily on older forest sites: the Del Norte salamander (Plethodon elongatus), the Olympic salamander (Rhyacotriton olympicus), and the tailed frog (Ascaphus truei). Paleoeco-logic evidence indicates an historical association between these three amphibians and the extant elements of ancient primeval coniferous forests of the Pacific Northwest. The life histories and habitat requirements of these species suggest that these forms are scarce in younger forests because the microclimatic and microhabitat conditions they require generally exist only in older forests. The long-term viability of these species in northern California and southern Oregon may depend upon developing forestry practices that protect these mitical microclimates and microhabitats.     

Founding Lineages and Genic Variability in Plains Bison (Bison bison) from Badlands National Park, South Dakota

Abstract: Starch-gel electrophoresis was used to screen 101 bison from Badlands National Park, South Dakota, for variation at 24 genetic loci. The population was descended from founder groups of about 6 and 3 individuals, separated geographically for a minimum of 64 years. The purpose of this study was (1) to estimate levels of genic variability in this bison population, (2) to assess the extent to which descendents of the two founder groups differ genetically, and (3) to compare the genetic characteristics of the Badlands population with other bison populations. The Badlands herd was found to be polymorphic for only a single locus (MDH–1). Descendents of the founder groups were homogeneous with respect to allelic and genotypic frequencies at this locus. The MDH–1 polymorphism has not been observed in other bison populations, while several polymorphism reported in other bison populations were not detected in the Badlands herd. A mean heterozygosity of 0.012 was observed in the Badlands herd; this value is lower than that typically reported for mammals, though not as low as heterozygosities seen in other populations that have passed through severe bottlenecks in size. These results underscore the need for genetic data in planning breeding programs for species in captivity or managed in isolate reserves.     

Lands for Long-Term Research in Conservation Biology

Abstract: Success in conservation biology depends upon a synergistic combination of short-term tactics and long-term strategies. Although the former are often necessary to forestall immediate habitat losses, the latter provide the critical framework of understanding needed to develop effective short-term priorities. Although many conservation biologists now emphasize short-term tactics, prudence dictates the concomitant establishment of long-term research projects aimed at answering fundamental ecological questions.
One deterrent to amassing such long-term data bases, aside from time and funding, is a lack of suitable sites where such studies can be conducted on a large scale. We describe two established major land-holding networks in the United States that could serve as appropriate places to develop long-term studies: the National Science Foundation's Long-Term Ecological Research (LTER) sites, and the US. Department of Energy's National Environmental Research Parks (NERPs). Because they consist of established research facilities, both networks can provide conservation biologists with "low-cost" baseline information on ecological processes, as well as access to a number of representative terrestrial and aquatic habitats under more or less "controlled" conditions suitable for long-term studies. We recommend that conservation biologists explore the possibility of using these or similarly available sites in their research programs.     

Effects of Forest Fragmentation on Understory Hummingbirds in Amazonian Brazil

We sampled understory hummingbirds in Amazonian forest fragments from before isolation through nine years after isolation. We recorded 377 captures of eight species in five 1-ha fragments and four 10-ha fragments. The three species netted before isolation, Phaethornis superciliosus, Phaethornis bourcieri , and Thalurania furcata , were nearly equally abundant at that time. After isolation abundance of P. bourcieri and T. furcata did not change, but P. superciliosus became nearly twice as common. Five additional species that were netted only after isolation represented about 10% of the post-isolation sample. The species recorded only after isolation were forest species usually found above the levels of nets; fragments were not colonized by nonforest species. Use of fragments did not differ between 1- and 10-ha fragments. The landscape surrounding the fragments included active cattle pasture, abandoned pasture, and Cecropia -dominated second growth, but this variation had little effect on use of fragments by hummingbirds. The results suggest that these understory hummingbirds can persist in a matrix of fragments, secondary growth, and large forest patches. This response is much different than that of the insectivorous birds that dominate the understory bird community at the site, which are much more vulnerable to fragmentation.     

Impact of predation-disturbance by large epifauna on sediment-dwelling harpacticoid copepods: Field experiments in a subtidal seagrass bed

The hypothesis was tested that predation-disturbance by epibenthic macrofauna affects the abundance of sediment-dwelling harpacticoid copepods. The copepods inhabited a subtidal seagrass (Zostera marina L.) bed in British Columbia, Canada. The response of the harpacticoid community was observed in controlled field experiments in which epibenthic predators-disturbers were excluded from portions of the seagrass bed. Controlled, exclusion-cage (0.8 m² area, 7-mm mesh) experiments were conducted within the seagrass bed from late March/early April to mid-June in both 1986 and 1987. Sampling was conducted biweekly. Exclusion of large epibenthic predators-disturbers had little effect on sediment-dwelling harpacticoid copepod density. Total harpacticoid numbers and abundances of dominant species generally did not increase in the exclusion treatment relative to the control. Shifts in species composition of the harpacticoid community did not occur. The treatment control was adequate in simulating the exclusion cage structure. It appears that large epibenthic predators-disturbers have little impact on the abundance of harpacticoid copepod populations at this study site.     

Infrastructure and Conservation Policy in Brazil

Abstract:  The development of transportation and energy infrastructure has been a major driver in the conversion of natural ecosystems in Brazil since the nineteenth century. Although this pattern is present in most countries, Brazil differs in the scale of opportunities that are still available to build its physical infrastructure while pursuing an ambitious conservation agenda. This advantage stems from the magnitude of intact ecosystems, a dynamic policy environment, and the increasing availability of biological and economic data needed to harmonize conservation with public works. Success depends on integrating conservation and infrastructure planning, rather than relying on the project based, largely ineffective environmental assessment process. Front-loading environmental mitigation and compensation will also help, as will improving public access to, and understanding of, information on the environmental and economic values at stake in major infrastructure decisions.