Sporocysts isolated from the southern copperhead (Agkistrodon contortrix contortrix) produce Sarcocystis montanaensis-like sarcocysts in prairie voles (Microtus ochrogaster)

Sporulated oocysts and free sporocysts of a Sarcocystis sp. were isolated from the feces of a southern copperhead (Agkistrodon contortrix contortrix) collected in Arkansas (USA). Twenty sporocysts measured 11.2 by 8.5 microns, lacked a Stieda body, and had four sporozoites and a granular sporocyst residuum. Sarcocysts similar to those of Sarcocystis montanaensis were present in the tongues of prairie voles (Microtus ochrogaster) inoculated orally with 800 sporocysts 128 days previously. Sarcocysts were thin-walled, divided into compartments by septa, and had electron dense projections (0.14 microns) on the primary cyst wall. Infection was not pathogenic for prairie voles under the conditions of this study. No infections were observed in ICR strain laboratory mice (Mus musculus) or white-footed mice (Peromyscus leucopus) following oral inoculation of 800 sporocysts.     

Description of the oöcysts of two new species of Eimeria (Apicomplexa: Eimeriidae) from the rough earth snake Virginia striatula (Serpentes: Colubridae) in Texas and Arkansas

Coccidian oöcysts recovered from the faeces of rough earth snakes Virginia striatula (Serpentes: Colubridae) were found to represent two previously unreported eimerians. Oöcysts of Eimeria desotoensis n. sp. were found in 5/32 (16%) of the snakes and were spherical to ellipsoidal, 18.4 × 17.2 (15–21.5 × 15–19.5) μm, with a thin, single-layered wall; their shape-index (length/width) was 1.07 (1.00–1.23). A micropyle and oöcyst residuum were absent; polar granule were present in 33% of the oöcysts. The sporocysts were ovoidal, 11.5 × 7.6 (10.5–13 × 7–8) μm, with a Stieda body; their shape-index was 1.51 (1.30–1.68). The sporocyst residuum was moderate in size and composed of a cluster of granules. Oöcysts of Eimeria hobartsmithi n. sp. were found in 2/32 (6%) of the snakes and were subspherical to ellipsoidal, 18.0 × 15.7 (16–20 × 15–17) μm, with a thin, single-layered wall; their shape-index was 1.15 (1.02–1.32). A micropyle, oöcyst residuum and polar granule were absent. The sporocysts were elongate, 13.2 × 6.3 (12–14.5 × 6–6.5) μm, with a Stieda body; their shape-index was 2.10 (1.88–2.34). A large sporocyst residuum was present in each sporocyst, often obscuring the sporozoites. In addition to the two new species, oöcysts of E. striatula Upton & McAllister, 1990 were observed in 38% of the snakes.     

High- and low-latitude forcing of Plio-Pleistocene East African climate and human evolution

The late Cenozoic climate of East Africa is punctuated by episodes of short, alternating periods of extreme wetness and aridity, superimposed on a regime of subdued moisture availability exhibiting a long-term drying trend. These periods of extreme climate variability appear to correlate with maxima in the 400-thousand-year (kyr) component of the Earth's eccentricity cycle. Prior to 2.7 Ma the wet phases appear every 400 kyrs, whereas after 2.7 Ma, the wet phases appear every 800 kyrs, with periods of precessional-forced extreme climate variability at 2.7-2.5 Ma, 1.9-1.7 Ma, and 1.1-0.9 Ma before present. The last three major lake phases occur at the times of major global climatic transitions, such as the onset of Northern Hemisphere Glaciation (2.7-2.5 Ma), intensification of the Walker Circulation (1.9-1.7 Ma), and the Mid-Pleistocene Revolution (1.0-0.7 Ma). High-latitude forcing is required to compress the Intertropical Convergence Zone so that East Africa becomes locally sensitive to precessional forcing, resulting in rapid shifts from wet to dry conditions. These periods of extreme climate variability may have provided a catalyst for evolutionary change and driven key speciation and dispersal events amongst mammals and hominins in East Africa.     

Estimating the number of terrestrial organisms on the moon

NASA policy requires that the number and spatial distribution of terrestrial organisms deposited on the Moon be estimated. This paper describes the way in which such an ‘inventory’ is being maintained, and some of the conclusions that may be drawn from it. This work was conducted under Contract W-12,853, Planetary Programs, Office of Space Science and Applications, NASA Headquarters, Washington, D.C.     

An observation about the relative hardiness of bacterial spores and planetary quarantine

Currently, planetary quarantine spacecraft sterilization requirements are based on the logarithmic model of bacterial death. This model is a single parameter exponential model in which the sole parameter is the decimal reduction time (D-value). The D-value associated with the sterilization of a population of bacteria is only a relative measure of the rate of bacterial inactivation: It is known to depend upon many factors, but generally these dependencies are not thoroughly understood. The D-values chosen for spacecraft sterilization have been selected conservatively relative to defined experimental procedures and bacterial spore stocks. New data indicate that these D-values are not conservative when compared with those of naturally occurring organisms. The possible implications of these new data for planetary quarantine are analyzed here.This work was conducted under Contract W-12,853, Bioscience Division, Office of Space Science and Applications NASA Headquarters, Washington, D.C.     

A new species of coccidian (Apicomplexa: Eimeriidae) from the prairie racerunner, Cnemidophorus sexlineatus viridis (Sauria: Teiidae), in Arkansas.

Feces from 26 prairie racerunners, Cnemidophorus sexlineatus viridis Lowe, 1966, from Arkansas, were examined for coccidian parasites. One of these was found to be infected with oocysts of an undescribed eimerian, which is described herein as new. Sporulated oocysts of Eimeria sexlineatus n. sp. were cylindrical, 30.4 x 17.1 (28-32 x 16-19) microns, with a shape index (length/width) of 1.8 (1.6-2.0). A micropyle and oocyst residuum were absent but 1 (to several) polar granule(s) was present. Sporocysts were ellipsoidal, 10.7 x 8.5 (9.6-11.2 x 8.0-8.8) microns, with a shape index of 1.3 (1.2-1.4). A sporocyst residuum was present but Stieda, substieda, and parastieda bodies were absent. Sporozoites were elongate, 13.2 x 2.7 microns (12.0-14.4 x 2.4-3.2) in situ, containing a single, spherical posterior refractile body. Oocysts and endogenous developmental stages were found within the gall bladder epithelium of the infected lizard. This represents the first time a coccidian has been reported from a North American whiptail lizard.     

Description of the oöcysts of Eimeria septemvittata n. sp. (Apicomplexa: Eimeriidae) from queen snakes,Regina septemvittata (Serpentes: Colubridae), in Arkansas

Coccidian oöcysts recovered from the feces of queen snakes, Regina septemvittata, from Arkansas, USA, were found to represent a previously unreported eimerian. Oöcysts of Eimeria septemvittata n. sp. are spherical or subspherical, 14.6×14.0 (12–16×12–15) μm, with a thin, bi-layered wall; the shape-index (length/width) is 1.04 (1.00–1.17). The micropyle and oöcyst residuum are absent but a large polar granule is present. The sporocysts are ovoidal, 11.3×5.6 (9.5–13.5×5–6) μm and possess a Stieda body; the shape-index is 2.02 (1.81–2.50). Each sporozoite contains a large, centrally located refractile body and a generally smaller, posterior refractile body.     

Hidden diversity in diatoms of Kenyan Lake Naivasha: a genetic approach detects temporal variation

This study provides insights into the morphological and genetic diversity in diatoms occurring in core sediments from tropical lakes in Kenya. We developed a genetic survey technique specific for diatoms utilizing a short region (76-67 bp) of the ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit (rbcL) gene as genetic barcode. Our analyses (i) validated the use of rbcL as a barcoding marker for diatoms, applied to sediment samples, (ii) showed a significant correlation between the results obtained by morphological and molecular data and (iii) indicated temporal variation in diatom assemblages on the inter- and intra-specific level. Diatom assemblages from a short core from Lake Naivasha show a drastic shift over the last 200 years, as littoral species (e.g. Navicula) are replaced by more planktonic ones (e.g. Aulacoseira). Within that same period, we detected periodic changes in the respective frequencies of distinct haplotype groups of Navicula, which coincide with wet and dry periods of Lake Naivasha between 1820 and 1938 AD. Our genetic analyses on historical lake sediments revealed inter- and intra-specific variation in diatoms, which is partially hidden behind single morphotypes. The occurrence of particular genetic lineages is probably correlated with environmental factors.     

The testicular sperm ducts and genital kidney of male Ambystoma maculatum (Amphibia,Urodela, Ambystomatidae)

The ducts associated with sperm transport from the testicular lobules to the Wolffian ducts in Ambystoma maculatum were examined with transmission electron microscopy. Based on the ultrastructure and historical precedence, new terminology for this network of ducts is proposed that better represents primary hypotheses of homology. Furthermore, the terminology proposed better characterizes the distinct regions of the sperm transport ducts in salamanders based on anatomy and should, therefore, lead to more accurate comparisons in the future. While developing the above ontology, we also tested the hypothesis that nephrons from the genital kidney are modified from those of the pelvic kidney due to the fact that the former nephrons function in sperm transport. Our ultrastructural analysis of the genital kidney supports this hypothesis, as the basal plasma membrane of distinct functional regions of the nephron (proximal convoluted tubule, distal convoluted tubule, and collecting tubule) appear less folded (indicating decreased surface area and reduced reabsorption efficiency) and the proximal convoluted tubule possesses ciliated epithelial cells along its entire length. Furthermore, visible luminal filtrate is absent from the nephrons of the genital kidney throughout their entire length. Thus, it appears that the nephrons of the genital kidney have reduced reabsorptive capacity and ciliated cells of the proximal convoluted tubule may increase the movement of immature sperm through the sperm transport ducts or aid in the mixing of seminal fluids within the ducts. © J. Morphol., 2013. © 2012 Wiley Periodicals, Inc.