Murine T cell determination of pregnancy outcome.

At the fetomaternal interface, maternal effector cells come in intimate contact with fetal trophoblast cells which express paternal antigens. Failure of fetal trophoblast cells to activate maternal Th1 immune responses has been attributed in part to the absence of classical Class I and Class II major histocompatibilty complex (MHC) antigen expression and elaboration of factors which reduce TcR expression and shift any immune responses which may occur to Th2. Classical TcR alphabeta(+) T cells have not been found to be able to respond to trophoblasts. Recently, TcR gammadelta(+) T cells have been characterized in the low-abortion-rate pregnant C57Bl/10 mouse decidua, and the Vgamma1(+) subset may be able to respond to trophoblasts in a non-MHC-dependent manner. Trophoblast-recognizing T cells with Vgamma1 receptors are also present in the decidua of CBA/J mice pregnant by DBA/2, an abortion-prone mating combination. To test the role of the Vgamma1 subset of decidual gammadelta T cells in abortion-prone pregnancies, we altered this subset by injecting monoclonal anti-Vgamma1.1 antibody on gestation day 5.5, 1 day after implantation. This reduced detectability of a Vgammadelta subset producing TNF-alpha and reduced the abortion rate. Anti-Vgamma2, which reacts with a similar proportion of decidual gammadelta T cells as anti-Vgamma1.1, failed to prevent abortions. Vdelta6.3(+) cells are prominent at the fetomaternal interface, and anti-Vdelta6 antibody injected on day 5.5 prevented abortions. TGF-beta2(+) gammadelta cells first appear on day 8.5 of pregnancy; anti-Vgamma1.1 antibody injection on day 8.5 depleted these cells and boosted abortions; anti-Vdelta6.3 given on day 8.5 boosted abortions to the same level. These results suggest that two populations of Vgamma1.1(+)delta6.3(+) T cells may arise in the decidua: an early population that is Th1, abortogenic, and present during the time of implantation, and a Th2/3 cell subset that is present in the decidua later during pregnancy and which is pregnancy-protective.     

A test of two hypotheses explaining the seasonality of reproduction in temperate mammals

1. Two proposed hypotheses about energy allocation were tested to explain the patterns of seasonal reproduction found in temperate mammals. The two hypotheses predict either that total demand for energy is greater during reproduction than during winter (when thermoregulatory costs are high) (Increased Demand Hypothesis) or that total costs during winter are greater than or equal to total costs during reproduction (Reallocation Hypothesis).
2. Data were compiled from the literature on summer (non-reproducing) and winter metabolic rates of temperate mammals, and were used on litter sizes and a published equation to predict metabolic rates during lactation.
3. All three measures of metabolic rate scaled to body mass with slopes significantly less than one. Metabolic rates during winter averaged ≈ 2 times greater than those of non-reproducing mammals during summer. On average, predicted metabolic rates during lactation were not significantly greater than during winter, but for some individual species they clearly were.
4. It is suggested that neither the Reallocation nor the Increased Demand Hypothesis can fully explain seasonal reproductive patterns in temperate mammals.     

Carbon dioxide and temperature effects on forage establishment: tissue composition and nutritive value

Atmospheric CO₂ concentration ([CO₂]) and temperature are likely to increase in the future and may change plant growth and composition characteristics. Rhizoma peanut (Arachis glabrata Benth.) and bahiagrass (Paspalum notatum Flügge) were grown on a natural field soil in temperature-gradient greenhouses to evaluate the effects of elevated [CO₂] and temperature on tissue composition and digestibility during the establishment year. Carbon dioxide levels were maintained at 365 (ambient) and 640 μL CO₂ L^–1 air. The temperature-gradient greenhouses were regulated to obtain air temperature sectors of 0.2, 1.5, 2.9, and 4.5 °C above ambient. Samples were taken of previously undefoliated herbage at 57, 86, 121, 148, and 217 days after planting and entire plots were harvested at 218 days after planting. Elevated [CO₂] increased total nonstructural carbohydrate concentration in rhizoma peanut leaves by almost 50%. Rhizoma peanut leaf N concentration was 6% lower at elevated than at ambient [CO₂]. The N concentration in new rhizomes of rhizoma peanut was increased by high [CO₂], while the N concentration in bahiagrass was not affected by temperature or [CO₂]. No effects of [CO₂] and temperature were found on neutral detergent fibre in rhizoma peanut leaves or stems; however, elevated [CO₂] increased neutral detergent fibre in bahiagrass leaves. Only at season end was in vitro organic matter digestion of rhizoma peanut higher at ambient (623 g kg^–1) than at elevated [CO₂] (609 g kg^–1). Elevated [CO₂] had a greater effect on tissue composition of rhizoma peanut than of bahiagrass. These data suggest that elevated temperature and CO₂-induced changes in chemical composition of forage species adapted to humid subtropics will be relatively small, particularly for C4 species.     

Muscle Restructuring in Crustaceans: Myofiber Death, Transfiguration and Rebirth

Research on the dimorphic claws of the snapping shrimp Alpheushas revealed moult-associated changes in structure and biochemicalcomposition—including atrophy and biochemical modification—ofclaw muscle fibers during morphological transformation of aclaw from a pincer to a snapper. Electrophysiology, SDS-PAGEgel electrophoresis, and immunocytochemistry were used to analyzechanges in claw closer muscle function and composition duringthe transformation process. Remodification of closer muscleduring claw transformation, involving the complete loss of acentral section of fast-contracting fibers and their replacementthrough enlargement of existing slowly-contracting segmentsof the muscle, may mimic similar muscle modifications duringinitial claw development. Exposure of intact animals to environmentalecdysteroid hormones accelerated the rate of these changes.These processes appear to be a product of a remarkable trophicplasticity of crustacean skeletal muscle first discovered bySkinner.     

Degeneration of solventogenic Clostridium strains monitored by Fourier transform infrared spectroscopy of bacterial cells

Strain degeneration in solventogenic clostridia is a known problem in the technical acetone–butanol fermentation bioprocess, especially in the continuous process mode. Clostridial strain degeneration was studied by Fourier transform infrared (FT-IR) spectroscopy of the bacterial cells. Degenerative variant formation in two strains, Clostridium beijerinckii NCIMB 8052 and Clostridium species AA332, was detected spectroscopically. Colonies on solid media were sampled, or assayed directly in situ by IR microscopy. It has previously been shown that the distinctive acidogenic and solventogenic physiological phases of Clostridium acetobutylicum in liquid medium can be discriminated by FT-IR spectroscopy. This was confirmed here for C. beijerinckii NCIMB 8052. The proportion of degenerate cells in a mixed population in liquid medium could be quantified, as the spectral features change in different ways during the normal growth cycle of wild type organisms and degenerate variants in batch culture. This opens a new perspective for physiology-based process monitoring and control, especially of the continuous acetone–butanol fermentation. Journal of Industrial Microbiology & Biotechnology (2001) 27, 314–321. Received 06 October 2000/ Accepted in revised form 20 April 2001     

Riverine distribution of mussel environmental DNA reflects a balance among density,transport, and removal processes

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