The Influence of Hyaluronidase and Hyaluronidase Substrates on Penetration of Cultured Cells by Eimerian Sporozoites

SYNOPSIS Leighton tube cultures of bovine embryonic kidney cells were inoculated with Eimeria adenoeides sporozoites suspended in media containing either hyaluronidase, hyaluronidase substrates (chondroitin sulfate and hyaluronic acid) or Ficoll. After 1 hr at 41 C, coverslips were removed and cells were fixed and stained. Hyaluronidase (1 and 10 mg/ml) did not increase the number of intracellular sporozoites. Chondroitin sulfate (1 and 10 mg/ml) and hyaluronic acid (1 mg/ml) did not reduce the number of intracellular sporozoites. However, the number was reduced when the media contained either chondroitin sulfate (100 mg/ml) or hyaluronic acid (5 mg/ml), which were quite viscous.
Ficoll (117 mg/ml), which produced the same viscosity as 5 mg hyaluronic acid/ml, also reduced the number of intracellular sporozoites. This finding circumstantially indicates that sporozoites may be physically inhibited from entering cells by the high viscosity of the substrates.
Biochemical tests, which detected as little as 0.2 μg of known hyaluronidase, failed to detect hyaluronidase activity in excysted intact or fragmented E. adenoeides sporozoites or in sporozoites within E. tenella oocysts.     

Comparative limnology of a deep-discharge reservoir and a surface-discharge lake on the Madison River, Montana

SUMMARY. Phytoplankton standing crop, primary production, light penetration, temperature, and various chemical concentrations were measured in a man-made, deep-discharge, reservoir and in a natural, surface-discharge, lake in order to relate limnological conditions in the two bodies of water to their depth of outflow. The quantity and depth distribution of heat stored during the summer varied markedly. The reservoir functioned as a heat trap, whereas heat was readily dissipated from the lake. Salinity increased more in the lower layer of the lake. Throughout the summer, nutrient-rich water was discharged from the reservoir whereas nutrient-poor water was discharged from the lake. Phytoplankton standing crops were greater in the lake and were dominated by flagellates and diatoms. In the reservoir, blue-green algae were predominant. Rates of primary production and respiration were higher in the lake, but estimated algal turnover times were faster in the reservoir. It was concluded that depth of outflow has a direct and predictable effect on certain physical and chemical conditions within these two bodies of water; but effects of discharge depth on phytoplankton were secondary and thus difficult to ascertain.     

Patterns of abundance of fire ants and native ants in a native ecosystem

Abstract 1. This correlational study examines the relationship between the red imported fire ant (Solenopsis invicta) and native ants in a longleaf pine savanna. Fire ants are frequently associated with a decline in native ants throughout the invaded range, but fire ant invasion is often coupled with habitat disturbance. Invasion of fire ants into the longleaf pine savanna provides an opportunity to examine the structure of the ant community in the absence of habitat disturbance. 2. Pitfall trapping was conducted within the longleaf pine savanna as well as across a naturally occurring soil moisture gradient, in plots that had been artificially watered. 3. Species richness did not vary as a function of fire ant density. There was an inverse relationship between native ant density and fire ant density, but this abundance pattern does not necessarily imply a causal link between fire ant invasion and native ant decline. For individual species, fire ant densities were negatively correlated with the densities of only two native ant species, including Solenopsis carolinensis, a native species that potentially limits the invasion of fire ants. Additionally, fire ants and native ants respond differently to soil moisture, with native ants favouring drier conditions than fire ants. 4. The possible exclusion of fire ants by some native ants, as well as differences in habitat preferences, provide alternative explanations for the frequently observed negative correlation between fire ants and native ants.     

Changes in sperm tail development associated with Y chromosome meiotic drive leading to an excess of males in the medfly Ceratitis capitata (Diptera: Tephritidae)

The Mediterranean fruit fly Ceratitis capitata (Wied.) normally produces the sexes in equal ratio but strains carrying the Y chromosome meiotic drive MP (male‐producing) factor show an excess of males. This is associated with a loss of sperm, and abnormal sperm structure in terms of multiple axonemes, atypical numbers of mitochondrial derivatives, and sometimes an incorrect initial orientation of paracrystalline bodies to the axoneme. Sperms are bundled together within spermatocysts, and those with depleted content and abnormalities occur in the same MP testes as normal spermatocysts. The maximum number of sperms per cyst in control strains was 256, each with a single axoneme originating from a single centriole (kinetosome). The maximum per cyst in MP strains was also 256 but MP cysts contained up to 300 axonemes, providing evidence of multiplication of centrioles. The structural changes in MP sperm are discussed in relation to similar abnormalities reported in the mosquito Aedes aegypti inheriting the Y chromosome meiotic drive haplotype MD. The evolutionary significance of this phenomenon is considered. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 351–359.