Diversity and Abundance of Litter Frogs in a Montane Forest of Southeastern Brazil: Seasonal and Altitudinal Changes1

We sampled litter frogs in an 1800-ha mid-elevation seasonal forest in southeastern Brazil. One hundred 8 * 8-m plots were sampled during the dry/cold season and wet/warm season (unburned areas); we also examined the effects of fire in recently burned areas. A total of 267 frogs (305 g), belonging to 16 species (4 families) were caught. A single species comprised 78.5 percent of the individuals in the dry/cold season and 54.3 percent in the wet/warm season. The density of individuals did not change significantly with season, biomass did. Density and biomass of frogs were positively correlated with altitude. A Mantel test indicated that biological data (species and their abundance) were significantly associated with environmental parameters. The burned areas showed low values in richness, density and biomass of frogs. Harsh seasonal climate and a history of human disturbance may produce the low observed diversity values. The greater densities of frogs in sites of higher elevation may primarily result from mist-generated humidity, which diminishes the harshness of the dry/cold season in relation to lower sites.     

Delayed hypersensitivity and migration inhibition in two lines of mice genetically selected for high or low responsiveness to phytohemagglutinin

Delayed-type hypersensitivity (DTH) and cell migration inhibition (MI) were studied in two lines of mice genetically selected for the high (Hi/PHA) or low (Lo/PHA) in vitro response of their lymphoid cells to phytochemagglutinin (PHA). A rapid photoelectric procedure for reading cell migrations enabled the study of MI over a wide range (10 log) of antigen concentrations in vitro. Hi/PHA mice required immunization with a 10 times higher dose of ovalbumin (OVA) in Freund's complete adjuvant (FCA) than Lo/PHA mice for a comparable response in DTH (footpad swelling) and MI of their induced peritoneal exudate cells (PEC). Lo/PHA spleen showed marked bizonal MI on Day 5 after immunization with low doses (0.1 and 0.5 micrograms) of OVA in FCA, one peak being obtained in presence of in vitro concentrations of 10(-3) or 10(-2) micrograms/ml OVA and another peak at 1 or 10 micrograms/ml, whereas Hi/PHA spleen showed stimulation of migration. In contrast, MI in Lo/PHA spleen failed to persist beyond Day 19, whereas it appeared progressively in Hi/PHA spleen, being maximal by Day 27. Low-zone inhibition in Hi/PHA spleen and PEC was lacking or poor even after immunization with higher doses of OVA in FCA. The implications of these findings are discussed.     

Is foraging in the desert ant,Messor pergandei (Hymenoptera: Formiceidae), limited by water?

Abstract.

• 1 The seed-harvesting ant Messor (Veromessor) prrgandei (Mayr) is a common inhabitant of southwestern deserts of the U.S.A. Foragers vary in size from less than 1 mg to more than 10 mg in body mass and may travel over 80 m on a single foraging trip. Their small size, long foraging range, and hot, arid habitat suggest that water stress may limit foraging activity. We examined intercolony and interindividual variation in water loss of M.pergandei foragers under several different situations in the field.
• 2 Colonies differed significantly in minimum critical water content (W_c) of individual foragers (water content below which foragers are incapable of normal locomotion). In one colony small workers had disproportionately higher W_c than larger workers; in the other colony W_c was isometric with body size.
• 3 Groups of workers confined in the field approached W_c only after normal foraging stopped and substrate temperatures exceeded 45°C, while water content of individual foragers did not approach the W_c during normal foraging periods. Moreover, seed load and distance travelled did not negatively affect forager water content, as measured on return to the nest: indeed, our results suggest that forager hydration level may influence load selection and/or foraging distance. We conclude that, under normal circumstances, foraging in M.pergandei is not water-limited.

     

A MORPHOLOGICAL AND TAXONOMIC CONSIDERATION OF TABELLARIA (BACILLARIOPHYCEAE) FROM THE NORTHCENTRAL UNITED STATES1,2

The taxonomy, distribution, and ecology of the diatom genus Tabellaria Ehr. from a portion of the northcentral United States were studied from collections made from August 1968 to October 1971. Using the transmission electron microscope with carbon replicas of the frustule surfaces, taxonomically significant characters were identified and related to those visible with the light microscope, four morphologically distinguishable taxa were recognized. The frustular morphology of T. fenestrata (Lyngbye) kütz. em. Knudson var. fenestrata was confirmed by both light and electron microscopy. T. flocculosa (Roth) Kütz. var. flocculosa is composed of 3 morphologically distinguishable strains. One of which is sufficiently different from the nominate variety to be described as T. flocculosa var. linearis var. nov. Also, a planktonic ecotype of one of the strains was identified.     

POPULATION CHARACTERISTICS AND MIGRATION OF SUMMER AND LATE-SEASON HUMPBACK WHALES (MEGAPTERA NOVAEANGLIAE) IN SOUTHEASTERN ALASKA

A total of 326 humpback whales (Megaptera novaeangliae) were individually identified in southeastern Alaska during five summer seasons (July to September) and four late seasons (November to February) spanning the years 1979 to 1983. Peak numbers of whales were found late in August or early in September. Whales arrived 1–2 wk later in 1982 than in 1981. Whales sighted in both the summer and late seasons of 1981 and 1982 remained about 3.7 mo and one whale remained for at least 4.9 mo. Humpback whales from southeastern Alaska wintered in Hawaiian or Mexican waters, but generally did not travel to other feeding regions. The most rapid migratory transit between Hawaii and southeastern Alaska was 79 d. Based on mark-recapture analyses of the photographic data, we estimate a population of 270–372 whales in the southeastern Alaska feeding herd.     

Subcellular localization of the heat-stable glucocerebrosidase activator substance in Gaucher spleen

The spleen in Gaucher's disease contains relatively large quantities of a heat-stable activator of the glucocerebrosidase of normal human tissues (Ho, M. W., and O'Brien, J. S. (1971) Proc. Nat. Acad. Sci. USA68, 2810–2813) that has been shown to be an 11,000 molecular weight acidic glycoprotein (Peters, S. P., et al. (1977) J. Biol. Chem.252, 563–573). In an effort to determine the subcellular location of the activator, a mannitol-sucrose homogenate of fresh, unfrozen spleen obtained from a 26-year-old patient with adult, nonneuropathic (Type 1) form of Gaucher's disease was subjected to subcellular fractionation. The tissue used in these experiments exhibited a β-glucocerebrosidase deficiency (11% of control tissue characteristic of Gaucher's disease. Mitochondrial and lysosomal fractions obtained by centrifugation of the spleen homogenate at 6900 and and 20,000g, respectively, contained greater than 80% of the recovered acid phosphatase and heat-stable glucocerebrosidase activator activities. In addition, 60% of the residual glucocerebrosidase activity was recovered in the mitochondrial and lysosomal fractions. The lysosomal and mitochondrial fractions were subjected to equilibrium sucrose density gradient centrifugation. Analysis of the sucrose gradient of the crude mitochondrial fraction demonstrated the mitochondrial marker enzyme (cytochrome oxidase) banding with a specific gravity of 1.19 g/ml, whereas the heat-stable activating factor banded in an acid phosphatase-rich fraction having a specific gravity of 1.12 g/ml. Sucrose gradient analysis of the crude lysosomal fraction obtained from differential centrifugation indicated the activating factor banding with a specific gravity of 1.12 g/ml. Coincident with the activating factor was glucocerebrosidase and acid phosphatase activity. Electron microscopic examination of fractions from each of the sucrose density gradients demonstrated that the glucocerebrosidase activating factor was located in the same acid phosphatase-rich fractions that contained the characteristic Gaucher deposits. Furthermore, when Gaucher deposits were isolated and purified independently by a sucrose gradient procedure, they were found to contain high concentrations of the heat-stable glucocerebrosidase activator. The specific activity of the glucocerebrosidase activating factor was approximately 15-fold greater in the extensively purified Gaucher deposits than in the crude extract of Gaucher spleen from which the deposits were isolated. These observations indicate that the heat-stable activator is associated with the storage deposits contained in lysosomes of the Gaucher cell.     

Potential transmission of West Nile virus in the British Isles: an ecological review of candidate mosquito bridge vectors

West Nile virus (WNV) transmitted by mosquitoes (Diptera: Culicidae) infects various vertebrates, being pathogenic for birds, horses and humans. After its discovery in tropical Africa, sporadic outbreaks of WNV occurred during recent decades in Eurasia, but not the British Isles. WNV reached New York in 1999 and spread to California by 2003, causing widespread outbreaks of West Nile encephalitis across North America, transmitted by many species of mosquitoes, mainly Culex spp. The periodic reappearance of WNV in parts of continental Europe (from southern France to Romania) gives rise to concern over the possibility of WNV invading the British Isles. The British Isles have about 30 endemic mosquito species, several with seasonal abundance and other eco-behavioural characteristics predisposing them to serve as potential WNV bridge vectors from birds to humans. These include: the predominantly ornithophilic Culex pipiens L. and its anthropophilic biotype molestus Forskal; tree-hole adapted Anopheles plumbeus Stephens; saltmarsh-adapted Ochlerotatus caspius Pallas, Oc. detritus Haliday and Oc. dorsalis (Meigen); Coquillettidia richiardii Ficalbi, Culiseta annulata Schrank and Cs. morsitans (Theobald) from vegetated freshwater pools; Aedes cinereus Meigen, Oc. cantans Meigen and Oc. punctor Kirby from seasonal woodland pools. Those underlined have been found carrying WNV in other countries (12 species), including the rarer British species Aedes vexans (Meigen), Culex europaeus Ramos et al., Cx. modestus Ficalbi and Oc. sticticus (Meigen) as well as the Anopheles maculipennis Meigen complex (mainly An. atroparvus van Thiel and An. messeae Falleroni in Britain). Those implicated as key vectors of WNV in Europe are printed bold (four species). So far there is no proof of any arbovirus transmission by mosquitoes in the British Isles, although antibodies to Sindbis, Tahyna, Usutu and West Nile viruses have been detected in British birds. Neighbouring European countries have enzootic WNV and human infections transmitted by mosquito species that are present in the British Isles. However, except for localized urban infestations of Cx. pipiens biotype molestus that can be readily eliminated, there appear to be few situations in the British Isles where humans and livestock are exposed to sustained risks of exposure to potential WNV vectors. Monitoring of mosquitoes and arbovirus surveillance are required to guard the British Isles against WNV outbreaks and introduction of more anthropophilic mosquitoes such as Stegomyia albopicta (Skuse) and Ochlerotatus japonicus (Theobald) that have recently invaded Europe, since they transmit arboviruses elsewhere.     

The Invasion of the Chinese Mitten Crab (<Emphasis Type="Italic">Eriocheir sinensis</Emphasis>) in the United Kingdom and Its Comparison to Continental Europe

Owing to its catadromous lifestyle, the Chinese mitten crab, Eriocheir sinensis, allows comparison between a coastal and an inland biological invasion of the same species. Information about the distribution of this species in the United Kingdom has been collected from sightings made by governmental agencies, The Natural History Museum (London) collection, literature, and from the general public. This information indicated that the range of the species has expanded since the species’ arrival in 1973. The spread has been most marked along the east coast northwards to the river Tyne, on the south coast westwards to the river Teign. The expansion range was quantified and compared using geographic information software, and then compared to recorded spread in Europe. Mitten crabs dispersed along the coast at an average rate of 78 km per year (1976–1999), with a recent sharp increase to 448 km per year (1997–1999). These values are comparable with the historic outbreak in continental Europe where the average rate of dispersion along the Baltic Sea coast (1928–1935) was 416 km per year. Comparable figures for the North Sea coast (1923–1954) were 75 km per year with a peak of 168 km per year in 1927–1937. The upstream spread along rivers in the United Kingdom was 16 km per year in 1973–1998 with a marked increase since 1995 to 49 km per year (1995–1998). These data, in combination with population data published for the river Thames, indicate that the population has been increasing since the early 1990s, causing further range expansion into previously uninvaded river systems. The comparison of the spreading behaviour of the ongoing invasion in the United Kingdom with the historic invasion in northern Europe suggests that E. sinensis in future has the potential to establish itself in all major UK estuaries.     

The Clinic and Elsewhere: Illness,Sexuality, and Social Experience Among Young African American Men in Baltimore,Maryland

This paper is concerned with how disclosure becomes self-production for young adults within the setting of the sexually transmitted disease (STD) clinic. The STD clinic is a special medical environment where the process of disclosure is not just a way of accessing treatment; it is also a process through which illness, sexuality, and social experience become entangled in telling. Illness according to medical categories is reshaped in the social world, bringing a different set of criteria to bear on the definition of illness. The concern we raise regards how meaning is secured simultaneously through the experience of illness and social relations. Using data from a series of clinic-based ethnographic interviews, we examine the narratives of three young men. Together, the narratives demonstrate the interrelatedness of illness and self-production in various forms. In one case the tension between interpersonal violence and self-preservation is central. In another, the place of knowledge in family relationships renders the entire picture of the social unstable. The paper signals a number of issues absent in clinical and epidemiological depictions of vulnerability, particularly in the context of the urban United States.     

Serum zinc levels in healthy subjects from southeastern Spain

The serum zinc (Zn) concentrations of 80 healthy subjects (48 male, 32 female) from southeastern Spain were determined by atomic absorption spectrometry. The samples were digested by heating in a 4:1 mixture of nitric and perchloric acids. The concentration of Zn was determined against a Contox Trace Metal Serum Control Panel A standard reference. Zn concentrations in the standard were found to be 2.332 ±0.489 mg/L, with a mean recovery of 102.7%. In the serum samples, the relative standard deviation was <6% for the range of concentrations determined: 0.420-1.540 mg/L for women (mean value 0.947 ±0.265 mg/L) and 0.490-1.480 mg/L for men (mean value 0.951 ±0.243 mg/L). In healthy subjects, no statistically significant differences were observed in the Zn levels with respect to their sex (p > 0.05) or the location where they lived (mountainous vs coastal zones). It is concluded that the dietary Zn intake and Zn status for healthy adults in this region of Spain are within normal values.