A Malaria Parasite, Plasmodium aurulentum sp. nov. from the Neotropical Forest Gecko Thecadactylus rapicaudus

SYNOPSIS. Plasmodium aurulentum sp. nov. from the neotropical forest gecko Thecadactylus rapicaudus in Panama is characterized by oval or round to lenticular gametocytes, 6–22 nuclei in crudely fan-shaped schizonts, and light golden pigment masses. A prominent, pinkish red-staining mass, present in older schizonts, disappears by the time schizonts reach maturation.     

Induction of Biochemical Differentiation in Three-Dimensional Collagen Cultures of Mammary Epithelial Cells from Virgin Mice

In order to reduce cellular complexity in the study of the controls of the biochemical differentiation of mammary gland epithelium, approximately 100-fold purified epithelial cells from the mammary glands of virgin BALB/c mice were grown in three-dimensional collagen gels, and formed colonies that resembled mammary ductules. Here we report the induction of a biochemical differentiation in these purified epithelial cells in response to appropriate hormonal signals, starting from the state in the virgin mammary gland and ending with the stage characteristic of lactation. Induction of the synthesis of caseins was examined as a marker of mammary functional differentiation using sensitive immunologic autoradiography. The cells were maximally induced by the combination of the hormones, insulin, prolactin, aldosterone, and hydrocortisone, in both serum-containing and essentially serum-free media. The induction required insulin and prolactin, and was enhanced by the presence of the steroids. The cellular distribution of the induction was general, inasmuch as three-quarters of the hormone-stimulated cells were casein-positive according to immunocytochemistry. In order to assess the role of the three-dimensional conformation in the induction process, the purified mammary epithelial cells were grown as monolayers on plastic and collagen-coated surfaces. In these two-dimensional cultures, the synthesis of casein was not induced, suggesting that cell shape, orientation, and multicellular organization are important parameters in the hormonal induction of the biochemical differentiation. The finding of the induction of differentiation-specific proteins in cultures of purified epithelial cells from virgin glands allows examination of the molecular mechanisms involved in the complete induction process in the virtual absence of fat cells, fibroblasts, and the complex assortment of biochemical constituents of the mammary fat pad.     

The effect of soil warming on bulk soil vs. rhizosphere respiration

There has been considerable debate on whether root/rhizosphere respiration or bulk soil respiration is more sensitive to long-term temperature changes. We investigated the response of belowground respiration to soil warming by 3 °C above ambient in bare soil plots and plots planted with wheat and maize. Initially, belowground respiration responded more to the soil warming in bare soil plots than in planted plots. However, as the growing season progressed, a greater soil-warming response developed in the planted plots as the contribution of root/rhizosphere respiration to belowground respiration declined. A negative correlation was observed between the contribution of root/rhizosphere respiration to total belowground respiration and the magnitude of the soil-warming response indicating that bulk soil respiration is more temperature sensitive than root/rhizosphere respiration. The dependence of root/rhizosphere respiration on substrate provision from photosynthesis is the most probable explanation for the observed lower temperature sensitivity of root/rhizosphere respiration. At harvest in late September, final crop biomass did not differ between the two soil temperature treatments in either the maize or wheat plots. Postharvest, flux measurements during the winter months indicated that the response of belowground respiration to the soil-warming treatment increased in magnitude (response equated to a Q ₁₀ value of 5.7 compared with ∼2.3 during the growing season). However, it appeared that this response was partly caused by a strong indirect effect of soil warming. When measurements were made at a common temperature, belowground respiration remained higher in the warmed subplots suggesting soil warming had maintained a more active microbial community through the winter months. It is proposed that any changes in winter temperatures, resulting from global warming, could alter the sink strength of terrestrial ecosystems considerably.     

Sexual Stages in the Life History of the Hemogregarine Hepatozoon rarefaciens (Sambon and Seligmann, 1907)*

SYNOPSIS. Sexual stages of a reptilian hemogregarine Hepatozoon rarefaciens are described from the hemocoele of a mosquito vector Culex tarsalis. The gametocytes associate within 0.5 hr after biting. Most of the gametocytes then pair off and begin to differentiate. After about 26 hr at 22–23 C, the macrogametocyte usually becomes crescent-shaped with the microgametocyte lying in the concavity. The nucleus of the macrogametocyte enlarges considerably, while the microgametocyte divides into 2 and eventually into 4 spindle-shaped microgametes which are biflagellated. The macrogametocyte increases in size and rounds up to form a macrogamete. Gamete formation is usually completed by 60 hr and fertilization begins soon thereafter. The zygotes develop into the uninucleate oocysts described previously. In some other species of Hepatozoon, gametogenesis has been described as taking place in the stomach of the arthropod vector, with the microgametocytes transforming without cytoplasmic division into non-flagellated microgametes. The occurrence of 2 distinct types of gametogenesis may possibly be a basis for separating Hepatozoon into 2 genera.     

Plasmodium sasai n. sp. from the Japanese Lizard Takydromus tachydromoides

SYNOPSIS. This is the 1st reptilian Plasmodium to be described from eastern Asia. It is apparently of limited geographic distribution. Experimental infections may result in the production of more parasites than red cells in the circulating blood. A single erythrocyte may be infected by as many as 11 parasites. Despite the heavy parasitemia and destruction of erythrocytes, the hosts are apparently not affected by the infection. Mature schizonts are frequently fan-shaped; they produce 7–17 merozoites. The asexual cycle has a high degree of synchrony.     

Longline Fisheries and Foraging Distribution of Flesh-Footed Shearwaters in Eastern Australia

ABSTRACT Incidental seabird mortality associated with bycatch during longline commercial fishing is a conservation concern. An initial step to estimating likelihood of seabird bycatch and conceiving conservation strategies is determining amount of overlap between foraging birds and commercial fishing effort, identifying oceanographic features associated with foraging birds, and quantifying dive characteristics. We tracked 24 adult flesh-footed shearwaters (Puffinus carneipes) breeding on Lord Howe Island located east of Australia during incubation and early and late chick-rearing periods from 6 January to 17 April 2005. At-sea foraging distribution of flesh-footed shearwaters was primarily confined within the jurisdictional Australian Fishing Zone. Foraging was strongly associated with sea-surface temperature >24°C. Spatial and temporal overlap of longline fishing with foraging shearwaters varied throughout the breeding season, but was greatest (63% overlap) during early chick-rearing. Mean maximum distance reached from the breeding colony during a foraging event was 804 km (SD = 280) from Lord Howe Island. Foraging behavior was strongly diurnal, with 91% of dives occurring during daylight, and most dives (77%) were <5 m. Given that longline fishing and flesh-footed shearwaters overlap substantially, the Australian Fisheries Management Authority should consider implementing additional regulations to further reduce bycatch. Conservation strategies such as setting longlines at nights may reduce flesh-footed shearwater bycatch.     

Use of SSCP to improve the efficiency of microsatellite identification from microsatellite‐enriched libraries

An inefficient aspect of marker identification from microsatellite‐enriched libraries is the proportion of clones with identical sequences. This can substantially increase the number of clones that need to be sequenced in order to identify a sufficient number of microsatellite loci. We propose the use of single‐stranded conformation polymorphism (SSCP) analysis to identify unique clones prior to sequencing. We used this approach prior to sequencing from microsatellite‐enriched libraries for three marine invertebrate species and were able to obtain a given number of unique clone sequences for only 28% of the sequencing effort that would have been required without SSCP screening.