The evolution of intermediate castration virulence and ant coexistence in a spatially structured environment

Theory suggests that spatial structuring should select for intermediate levels of virulence in parasites, but empirical tests are rare and have never been conducted with castration (sterilizing) parasites. To test this theory in a natural landscape, we construct a spatially explicit model of the symbiosis between the ant-plant Cordia nodosa and its two, protecting ant symbionts, Allomerus and Azteca . Allomerus is also a castration parasite, preventing fruiting to increase colony fecundity. Limiting the dispersal of Allomerus and host plant selects for intermediate castration virulence. Increasing the frequency of the mutualist, Azteca , selects for higher castration virulence in Allomerus , because seeds from Azteca -inhabited plants are a public good that Allomerus exploits. These results are consistent with field observations and, to our knowledge, provide the first empirical evidence supporting the hypothesis that spatial structure can reduce castration virulence and the first such evidence in a natural landscape for either mortality or castration virulence.     

Cloning and restriction fragment length polymorphism analysis of a cDNA for swine PIT-1, a gene controlling growth hormone expression*

A partial swine cDNA which encodes the functional domain of PIT-1 was isolated by the polymerse chain reaction (PCR). The swine PIT-1 cDNA clone is 95% identical at the protein level to the rat Pit-1 gene. Thus, Pit-l's known function in control of rat growth hormone and prolactin expression is likely to be conserved in swine. This swine cDNA clone was used to investigate genetic variability at PIT-1 in several American and Chinese breeds. Polymorphic BamIII fragments were found in pure-bred Meishan animals (n= 13), but only monomorphic fragments in five American breeds (n= 36).     

pH track of expanding bacterial populations

A method of pH distribution measurements in agar nutrient media containing expanding bacterial populations is described. It is based on measuring pH microsamples taken at different points of the media. The sample volume was 10 microliters. A pH sensitive field effect transistor was used as a measuring electrode. Acidification was found to occur in glucose media, while alkalization occurred in the media containing peptone.     

Phosphatases and phosphodiesterases isolated from the red king crab (Paralithodes camtschatica) hepatopancreas

Five enzymes have been isolated from the hepatopancreas of the red king crab Paralithodes camtschatica by means of ion exchange and gel chromatography: two acid (AcP) and one alkaline (AlkP) phosphomonoesterases, one alkaline phosphodiesterase (AlkPI), and one acid phosphodiesterase (AcPD). The pH optimum values of these enzymes are: AlkPs and AlkPD, 7.5; AcP, 5.5; and AcPD, 5.0. The activity of AlkP and AlkPD demands Mg²⁺ ions. The molecular weights of the enzymes (kDa) are the following: AlkP, 80; AcPs, 80 and 82; AlkPD, 51; and AcPD, 57. The enzymes are relatively thermostable (ID 50 from 47 to 62°C). AlkP is inhibited by NaCl (IC 50 at 0.4 M). The AcP, AcPD, and AlkPD activities are tolerant of high ionic strength.     

<Emphasis Type="Italic">Artemisia lerchiana</Emphasis> as a producer of essential oil

Abstrac  The composition of essential oil of Artemisia lerchiana Web. plants growing in Volgograd oblast was studied. Sampling was performed from plots contrasting in climatic and soil characteristics. Essential oil was obtained by hydrodistillation. The content of essential oil in shoot biomass increased gradually during shoot formation, flower bud formation, and flowering beginning and then decreased. The highest content of essential oil varied from 1.1 to 1.5% of plant dry weight at the stage of flower bud formation. More than thirty compounds were identified by gas chromatography-mass spectrometry. The following major components were found: camphor, borneol, bornylacetate, camphene, and 1,8-cineole. Some of compounds (sesquiterpenes and sesquiterpenoids) were identified for the first time. The time-course of accumulation of essential oil components strongly depended on habitat edaphic factors and climatic conditions during the year of sampling. The results permit a conclusion that A. lerchiana is a valuable producer of essential oils. Original Russian Text ? E.B. Kirichenko, Yu.V. Orlova, D.V. Kurilov, 2008, published in Fiziologiya Rastenii, 2008, Vol. 55, No. 6, pp. 934–941.