南海永暑礁晚全新世微型腹足类——盘足目,翼舌目,异旋目

本文主要描述了南海南沙群岛永署礁南永3井微型腹足类盘足目,翼舌目和异旋目共49个种,包括2个新种,Serpulorbis spiralis sp.nov.和Cerithiopsis bellatulus sp.nov.。这些种类个体非常微小,大多数小于2mm。绝大多数种类为典型的热带海区分子,它们具有广泛的地理分布。本文按Okutani(2000)分类系统进行了分类。绝大多数种类系南沙群岛海区首次记录。     

Observations on the Life Cycle of Eimeria bilamellata Henry, 1932 in the Uinta Ground Squirrel Spermophilus armatus*

SYNOPSIS. Oocysts of Eimeria bilamellata were found in Spermophilus armatus, Utah and Wyoming; S. beecheyi, California; and S variegatus, Utah. Oocysts were not found in S. lateralis, S. richardsoni, S. columbianus, S. tridecemlineatus, or the white-tailed prairie dog, Cynomys leucurus. Experimental infections were established in S. armatus, S. variegatus, and S. lateralis, but not in S. richardsoni, least chipmunks Eutamius minimus, laboratory rats Rattus norvegicus, or Mongolian gerbils Meriones unguiculatus. After one experimental infection S. armatus and S. variegatus were immune to further infections. Spermophilus lateralis could be infected 3 or 4 times before the animals were immune. However, individuals of S. armatus in a natural population had more than one infection with E. bilamellata; probably infections must be of a certain level before immunity develops. When S. armatus were inoculated with about 100,000 oocysts, the animals usually died on the 7th day after incoculation. Oocysts were 33-37 by 25-31 μ (mean 34.5 by 28.2 μ). The oocyst wall was brown and composed of 2 layers. A distinct micropyle was present. Sporocysts were 18-23 by 9-12 μ (mean 19.9 by 10.3 μ). In experimental infections, the prepatent period was 10 days and the patent period 5–21 (mean 9) days. Schizonts were 1st seen 7 days after inoculation. They were located above the host cell nuclei of epithelial cells at the tips of the villi of the jejunum and ileum. One or more earlier generations of schizonts were thought to occur, but these were not observed. Gametogony took place in epithelial cells of the jejunum and ileum. Shortly after the merozoites entered the cells, the cells became enlarged and were displaced into the lamina propria. The microgametocytes were considerably larger than the macrogametes and contained a central residual body. Macrogametes had a peripheral eosinophilic layer as well as cytoplasmic granules; both apparently participated in formation of the oocyst wall.     

Spatial Ecology of Raccoons Related to Cattle and Bovine Tuberculosis in Northeastern Michigan

ABSTRACT In 1995, Mycobacterium bovis, the causative bacterium of bovine tuberculosis (bTB), was detected in 5 beef cattle operations in Alcona County, Michigan, USA. In accordance with Federal law, the operations were depopulated to prevent the spread of bTB. Subsequent wildlife surveillance programs identified high prevalence of M. bovis in mesocarnivores, including raccoons (Procyon lotor), which suggested that raccoons may be complicit in vectoring the pathogen among livestock operations. Our goal was to develop an empirical basis for generating hypotheses about the likelihood for raccoons to mediate the transmission of bTB to livestock. We found intersexual differences in scale-dependent resource selection and probability of spatial interaction that, under certain circumstances, may form the foundation for a sex-bias in disease transmission. Spatial dispersion of mixed-forest patches facilitated overlap of adjacent males, whereas female overlap zones included pastures. Within overlap zones, probabilities of interaction for male-male and male-female dyads were greater than for female-female dyads, although we documented an elevated likelihood of spatial interaction between raccoons and livestock around cattle-feeding troughs and water sources, regardless of sex. Partial regressions generated by linear models indicated that distance between nearest-neighbor mixed-forest patches explained most of this observed variation. These results supported our prediction that forest patches juxtaposed with anthropogenic features fostered social tolerance between males and, thus, facilitated spatial interaction and exploitation of anthropogenic features. In raccoons, sex and landscape composition influenced pathogen transmission potential. We suggest that livestock producers locate livestock feeding and watering features away from forest patches to mitigate future outbreaks of bTB in endemic areas.     

Strcture of the Mature Embryo of Theobroma cacao L.

The mature embryo of Theobroma cacao L. consists of an embryonicaxis and two cotyledons. The cotyledonary tissue comprises thebulk of the embryo and contains mature and maturing vasculartissue surrounded by a bundle sheath. The cells of the groundtissue are filled with starch grains, anthocyanin pigments,or mucilage. The embryonic axis consists of epicotyl, hypocotyl,and root meristem. Maturation of the vascular tissue has begunin the procambium, where xylem maturation is ahead of phloemmaturation. Mucilage cells are found throughout the tissue of the axis.Most of the cells of the embryonic tissue contain starch grains.     

The Disruption of Dictyosome Structure, Polarity and Secretory Activity in the Scale-producing Green Alga, Pyramimonas inconstans

Domozych, D. S. and Korbusieski, T. J. 1985. The disruptionof dictyosome structure, polarity and secretory activity inthe scale-producing green alga Pyramimonas inconstans.—J.exp.Bot.36: 1304–1312. Dictyosome morphology and scale morphogenesis in the green alga,Pyramimonas inconstans, are well-defined ultrastructurally.By applying the sodium-specific ionophore, monensin, to actively-growingcell cultures, both dictyosome micro-architecture and the scale-basedsecretory pathway can be significantly altered. Applicationof 0.1 mol m³ and 0.01 mol m ^–3monensin for short periods(1 -3 h) results in cisternal curling and the disorientationof dictyosome polarity. Prolonged exposure to the ionophore(4-24 h) results in the complete disruption of dictyosome morphologyand scale morphogenesis with the emergence of irregular vesiclesfrom the maturing face. Removal of monensin by repeated washingreturns dictyosome structure and secretory activity to normal.These results indicate that Golgi apparatus integrity and secretoryactivity in Pyramimonas may be controlled by a localized, cytoplasmicproton gradient Key words: Monensin, Pyramimonas, dictyosome     

Functional differences between woodland savannas and seasonally dry forests from south‐eastern Brazil: Evidence from 15N natural abundance studies

Nitrogen availability and N‐cycling dynamics across ecosystems play a critical role in plant functioning and species distribution. Measurements of ¹⁵N natural abundance provides a way to assess ecosystem N dynamics, and the range of nitrogen stable isotope values (δ¹⁵N) for plants in an ecosystem can indicate divergent strategies for N uptake. We tested the hypotheses that the N‐rich seasonally dry forest would have higher soil and leaf δ¹⁵N and a smaller range of leaf δ¹⁵N values compared to the N‐poor cerradão (savanna woodland). We measured N concentration and δ¹⁵N in two soil depths and leaves of 27 woody species in cerradão and 26 in seasonally dry forest. As expected, total soil N concentration decreased while soil δ¹⁵N value increased with soil depth. Regardless of soil depth, seasonally dry forest soils had higher δ¹⁵N and total N concentration compared to cerradão soils. Foliar δ¹⁵N values varied from ?6.4‰ to 5.9‰ in cerradão and from ?2.3‰ to 8.4‰ in seasonally dry forest plants. Phylogenetically independent contrasts analysis and comparisons of δ¹⁵N mean values of the most abundant species and species co‐occurring in both sites confirmed the hypothesis of higher δ¹⁵N for seasonally dry forest in comparison to cerradão. These results corroborate the expectation of higher soil and leaf δ¹⁵N values in sites with higher soil N availability. However, except for the most abundant species, no across‐site leaf–soil (δ¹⁵N leaf –δ¹⁵N soil) differences (Δδ¹⁵N) were found suggesting that differences in leaf δ¹⁵N between cerradão and seasonally dry forest are driven by differences in soil δ¹⁵N. Variation of leaf δ¹⁵N was large in both sites and only slightly higher in cerradão, suggesting high diversity of N use strategies for both cerradão and seasonally dry forest communities.     

Physiological and ecological hosts of Popenaias popeii (Bivalvia: Unionidae): laboratory studies identify more hosts than field studies

1. Freshwater mussels are critically endangered in North America, making it important to understand their environmental requirements at all life stages. As glochidia (larvae), they attach to fish hosts where they undergo substantial mortality, making this transition important in their life cycle. Larval host fish requirements have typically been described using data from laboratory infestations to determine suitable hosts. 2. Laboratory infestations circumvent many natural barriers that prevent infestation of physiologically compatible fishes by mussel larvae. While such methods are invaluable for identifying ‘physiological hosts,’ they cannot fully describe realised ‘ecological hosts’ in the field. 3. We studied Popenaias popeii in the Black River in New Mexico, because it is of conservation concern and it is the only mussel species present, facilitating identification of glochidial infestation. To explore the difference between physiological hosts and ecological hosts, we conducted a 3‐year field study of fishes infested by P. popeii glochidia. 4. Substantially fewer fish species were infested by P. popeii in the wild (10 of 20 observed) than had been identified as physiological hosts in laboratory trials (24 of 31). We combined data on fish abundance, proportion of fish hosts infested (prevalence) and the number of glochidia per fish (intensity) and identified three fish species that probably contributed substantially more to mussel recruitment by carrying more glochidia than other host species. 5. Similarities in behaviour among these fishes allowed us to hypothesise routes of infestation, such as benthos‐feeding by catostomids, that allow glochidia to infest these hosts at higher rates than other suitable hosts. Overall, this approach provides a method of quantifying the relative importance of different species of host fish in the mussel lifecycle.