A Comparative Study of Lipid Compositions of Cryptosporidium parvum (Apicomplexa) and Madin-Darby Bovine Kidney Cells

Membrane lipid compositions of Cryptosporidium parvum and Madin-Darby bovine kidney cells, an epithelial-like cell line commonly used to study coccidia in vitro, were analyzed using both thin-layer chromatography and gas-liquid chromatography. Phosphatidylcholine was the predominant lipid in both C. parvum and Madin-Darby bovine kidney cells, comprising 65% and 41% of the total phospholipids, respectively. Phospholipids of C. parvum contained twice the level of 16:0 and twenty-fold more 18:2 than the Madin-Darby bovine kidney cell line. We suggest that the parasite may be capable of sequestering specific complex membrane lipids at concentrations greater than those in the host cells. This study constitutes the first report of the lipid composition of C. parvum .     

ALTERNATIVES TO NATIONAL AVERAGE INCOME DATA AS ELIGIBILITY CRITERIA FOR INTERNATIONAL SUBSIDIES: A SOCIAL JUSTICE PERSPECTIVE

Current strategies to address global inequities in access to life‐saving vaccines use averaged national income data to determine eligibility. While largely successful in the lowest income countries, we argue that this approach could lead to significant inefficiencies from the standpoint of justice if applied to middle‐income countries, where income inequalities are large and lead to national averages that obscure truly needy populations. Instead, we suggest alternative indicators more sensitive to social justice concerns that merit consideration by policy‐makers developing new initiatives to redress health inequities in middle‐income countries.     

Intra‐specific host preference for Littoraria filosa by the dipteran parasitoid Sarcophaga megafilosia: the consequences of attacking individuals outside the preferred size range

1. The marine snail, Littoraria filosa, lives on the leaves and trunks of mangroves. Populations of L. filosa are annual when its dipteran parasitoid Sarcophaga megafilosia is present, but perennial in its absence. 2. The size distribution of naturally occurring parasitised L. filosa suggests S. megafilosia has a distinct preference for snails with shells ≥ 10 mm long but, paradoxically, most individuals ≥ 18 mm long disappear from annual populations in late spring/early summer without appearing in the parasitised cohort. 3. When S. megafilosia was offered an unrestricted size range of L. filosa, only individuals >10 mm long were attacked and those from 19 to 20 mm long were preferred. 4. In no‐choice experiments, L. filosa <10 mm long were parasitised but pupation did not occur. For L. filosa >23 mm long, most attacked snails succeeded in ejecting the parasitoid larva but often lost their grip on the wall or ceiling of the cage and fell. Littoraria filosa is unlikely to survive such dislodgement from mangrove trees. 5. These results can explain the different size distributions of live and parasitised snails in the field, including the disappearance of large snails that do not subsequently appear in the parasitised cohort. However, this does not explain the preference by S. megafilosia for L. filosa around 19–20 mm for which more than 50% of attacks failed. This preference may be also determined by increased parasitoid fecundity and longevity as snail size increases. 6. If small differences in host size affect parasitoid fitness, it may help explain why attempts at biological control using known parasitoids of an exotic species are often ineffective or unsuccessful.     

Thermal requirements for seed germination in Miscanthus compared with Switchgrass (Panicum virgatum), Reed canary grass (Phalaris arundinaceae), Maize (Zea mays) and perennial ryegrass (Lolium perenne)

The high establishment costs of Miscanthus by clonal propagation are a barrier to widespread deployment. Direct sowing is the cheapest method, but limited field trials have given generally poor results. Miscanthus, a perennial grass with C₄ photosynthesis has tropical origins, but is found growing both at high latitudes (>40°) and altitudes (>1000 m) in Asia. In this paper, we investigate if significant variation in the thermal requirements for germination exist in 10 Miscanthus sinensis half‐sib families and compare these with Panicum virgatum (Switchgrass – Trailblazer), Phalaris arundinaceae (Reed canary grass – P10) and Lolium perenne (perennial ryegrass cv AberDart) and maize (Zea mays cv Aviso). The comparisons were made on a thermal gradient bar with a controlled temperature oscillating ± 5 °C on a 12 h cycle and germination was monitored daily for 35 days at mean temperatures ranging from 5.3 to 26.5 °C. Base temperatures were calculated below which germination of at least 50% of viable seeds ceased. Base temperatures were lowest for L. perenne and Zea mays at 3.4 and 4.5 °C respectively; for different Miscanthus half‐sib families base temperatures ranged between 9.7 and 11.6 °C and these were higher than maize and switchgrass which share C₄ photosynthesis with Miscanthus. Parameters derived from germination and temperature were used to predict germination patterns in Europe based on historical climate data. We predict that seed establishment of Miscanthus in spring time is unlikely to be viable in Northern Europe under present climatic conditions without crop management practices aimed at raising soil temperature, and that useful variation in thermal requirement for germination in Miscanthus is available which should facilitate seed germination in other regions.     

Characterization of Mouse Pmel 17 Gene and Silver Locus

Pmel 17 cDNA clones, isolated from wild-type and si/si murine melanocytes, were sequenced and compared. A single nucleotide (A) insertion was found in the putative cytoplasmic tail of the si/si Pmel 17 cDNA clone. This insertion is predicted to alter the last 24 amino acids at the C-terminus and to extend the Pmel 17 protein by 12 residues. The mutation was confirmed by the sequence of the PCR-amplified genomic region including the mutation site. Silver Pmel 17 was not recognized by antibodies directed toward the C-terminal amino acids of wild-type Pmel 17, indicating a defect in this region. These results indicate that silver Pmel 17 protein has a major defect at the carboxyl terminus.     

Sequence analysis of the mitochondrial DNA control region of ciscoes (genus Coregonus): taxonomic implications for the Great Lakes species flock

Sequence variation in the control region (D-loop) of the mitochondrial DNA (mtDNA) was examined to assess the genetic distinctiveness of the shortjaw cisco ( Coregonus zenithicus ). Individuals from within the Great Lakes Basin as well as inland lakes outside the basin were sampled. DNA fragments containing the entire D-loop were amplified by PCR from specimens of C. zenithicus and the related species C. artedi , C. hoyi , C. kiyi , and C. clupeaformis . DNA sequence analysis revealed high similarity within and among species and shared polymorphism for length variants. Based on this analysis, the shortjaw cisco is not genetically distinct from other cisco species.     

Comparing Ground Telemetry and Global Positioning System Methods to Determine Cougar Kill Rates

ABSTRACT We assessed whether use of 2 methods, intensive very high frequency (VHF) radiotelemetry and Global Positioning System (GPS) cluster sampling, yielded similar estimates of cougar (Puma concolor) kill rates in Yellowstone National Park, 1998–2005. We additionally determined biases (underestimation or overestimation of rates) resulting from each method. We used modeling to evaluate what characteristics of clusters best predicted a kill versus no kill and further evaluated which predictor(s) minimized effort and the number of missed kills. We conducted 16 VHF ground predation sequences resulting in 37 kill intervals (KIs) and 21 GPS sequences resulting in 84 KIs on 6 solitary adult females, 4 maternal females, and 5 adult males. Kill rates (days/kill and biomass [kg] killed/day) did not differ between VHF and GPS predation sampling methods for maternal females, solitary adult females, and adult males. Sixteen of 142 (11.3%) kills detected via GPS clusters were missed through VHF ground-based sampling, and the kill rate was underestimated by an average of 5.2 (95% CI = 3.8–6.6) days/kill over all cougar social classes. Five of 142 (3.5%) kills identified by GPS cluster sampling were incorrectly identified as the focal individual's kill from scavenging, and the kill rate was overestimated within the adult male social class by an average of 5.8 (95% CI = 3.0–8.5) days/ungulate kill. The number of nights (locations between 2000 hours and 0500 hours) a cougar spent at a cluster was the most efficient variable at predicting predation, minimizing the missed kills, and minimizing number of extra clusters that needed to be searched. In Yellowstone National Park, where competing carnivores displaced cougars from their kills, it was necessary to search extra sites where a kill may not have been present to ensure we did not miss small, ungulate prey kills or kills with displacement. Using predictions from models to assign unvisited clusters as no kill, small prey kill, or large prey kill can bias downward the number of kills a cougar made and bias upward kills made by competitors that displace cougars or scavenge cougar kills. Our findings emphasize that field visitation is crucial in determining displacement and scavenging events that can result in biases when using GPS cluster methods in multicarnivore systems.     

Comparison of urinary creatine with other biomarkers for detection of cadmium induced testicular damage

In this study, biomarkers of testicular damage were compared. In particular, urinary creatine was evaluated as a non-invasive marker of damage. Male rats were exposed to various doses of cadmium chloride, an established testicular toxicant. Pathological damage, testes weights, urinary creatine and creatinine, serum LDH-C4 and serum testosterone were determined. Cadmium chloride caused dose-dependent damage to the testes undetectable at the lowest dose (0.75 mg kg-1) but apparent at a dose of 1.125 mg kg-1. Urinary creatine was significantly raised after doses of 1.125 mg kg-1 and above 24-48 hr after dosing, and at the highest dose within 24 hr after dosing. Testes weight and serum testosterone were significantly decreased, and LDH-C4 significantly increased, at the highest dose (3.0 mg kg-l). Therefore urinary creatine was the most sensitive marker of acute cadmium-induced testicular damage and dysfunction.