Soil microbial communities resistant to changes in plant functional group composition

The soil community is an often ignored part of research which links plant biodiversity and ecosystem functioning despite their influence on numerous functions such as decomposition and nutrient cycling. Few consistent patterns have been detected that link plant and soil community composition. We used a removal experiment in a northern Canadian grassland to examine the effects of plant functional group identity on soil microbial community structure and function. Plant functional groups (graminoids, legumes and forbs) were removed independently from plots for five growing seasons (2003-2007) and in the fifth year effects on the soil microbial community were examined using substrate-induced respiration (SIR - a measure of metabolic diversity) and phospholipid fatty acid analysis (PLFA - a measure of microbial community composition). Removal treatments were also crossed with both a fertilizer treatment and a fungicide treatment to determine if effects of functional group identity on the soil community were context dependent. Plant functional group identity had almost no effect on the soil microbial community as measured by either SIR or PLFA. Likewise, soil properties including total carbon, pH, moisture and nutrients showed a limited response to plant removals in the fifth year after removals. We found a direct effect of fertilizer on the soil community, with fertilized plots having decreased metabolic diversity, with a decreased ability to metabolize amino acids and a phenolic acid, but there was no direct soil microbial response to fungicide. We show that in this northern Canadian grassland the soil microbial community is relatively insensitive to changes in plant functional group composition, and suggest that in northern ecosystems, where plant material is only slowly incorporated into the soil, five growing seasons may be insufficient to detect the impact of a changing plant community on the soil microbes.     

Nano-calcium carbonate reinforced polypropylene and propylene-ethylene copolymer nanocomposites: Tensile vs. impact behavior

Improvement of both the tensile and impact strength of the same polymeric material has always been a great challenge for the plastic industry. The study focuses on the effect of incorporation of calcium carbonate nanoparticles (0.3 wt% to 15 wt%) into three polypropylene (PP) based matrices viz. PP homopolymer, propylene-ethylene (PP-PE) copolymer and the blend of PP:PP-PE (30:70) to improve their impact behavior without hampering the tensile strength much. A loss in both the tensile and impact properties was observed in PP based nanocomposite. However, PP-PE based nanocomposites showed a significant improvement in impact strength (47 %) at 10 wt% loading with a loss of tensile strength by 22 %. To minimize this loss a blend of PP:PP-PE (30:70) was explored as a matrix. At 10 wt% loading, this matrix showed an improvement of 30 % in impact strength whereas the tensile loss was minimized to 10 %. Further, silane coupling agent which promoted good interfacial adhesion was used for best compositions. The variation of crystalline morphology of the nanocomposites with various formulations was analyzed using differential scanning calorimetry and X-ray diffraction.     

Euthanasia of honey-bee colonies: Proposal of a standard method

Honey bees are most often kept for production purposes. Sanitary, regulatory, or zootechnical circumstances may lead the beekeeper or the veterinarian to dispose of a honey-bee colony. Unfortunately and at present, no standard method of euthanasia exists, leaving the door open to many more or less acceptable practices. Based on a short survey of current practices in 8 countries, we list and rank these methods. Although imperfect, the sulfur dioxide technique appears to be the most efficient. We suggest that it should become the reference method to be taught and incorporated into veterinary and regulatory guidelines.     

A Fish of Weedy Waters: Golden Shiner Biology and Culture

The golden shiner, Notemigonus crysoleucas, is a major bait and forage fish species in the USA. Farmers produce millions of golden shiners annually that are distributed live, many across state boundaries. Native over much of the eastern and central USA, this species is often present but rarely abundant in natural systems, as fish density is apparently controlled by predation rather than by food resources. Aquaculture of the golden shiner is a century‐old practice and culture methods have evolved over time, resulting in today's farm‐raised, certified specific pathogen– and aquatic nuisance species–free baitfish. Federal and state agencies and universities have a long history of developing culture methods and promoting baitfish culture to replace the indiscriminate and wasteful harvest of fish from natural waters. Despite advances in culture methods and the advantages of a farm‐raised species produced under controlled and biosecure conditions, golden shiner farming is only marginally profitable and remaining farmers survive on farm equity and increased market share from others exiting the business. Ironically, increasing regulations and restrictions leading to a reduction in the supply of farm‐raised baitfish could drive anglers back to harvesting bait from natural waters, the very concern that initiated government support for baitfish culture a century ago.     

Response of Pacific White Shrimp,Litopenaeus vannamei,to Three Sources of Solvent Extracted Soybean Meal

Three sources of soybean meal (SBM) were biochemically characterized and evaluated in diets for juvenile Litopenaeus vannamei. Three biological techniques were utilized to evaluate the nutritional quality of the meals including an outdoor growth trial as well as determination of in vivo apparent digestibility and in vitro digestibility including pepsin digestibility (0.0002%), pH Stat degree of hydrolysis, and immobilized digestive enzyme assay (IDEA). The growth trial was conducted over a 10‐wk period using soybean meal as the primary protein source with each meal being included at 54–58% of the diet based on an equal protein inclusion. At the conclusion of the growth trial there were no significant differences between the test diets indicating equivalent biological availability under practical conditions. The in vivo digestibility trial utilized chromic oxide as the inert marker and 70:30 replacement techniques resulted in typical results. Apparent protein digestibility (APD) and apparent energy digestibility (AED) of the diets ranged from 66.8 to 80.2% and 65.4 to 74.7%, respectively. Ingredient digestibility values for protein and energy ranged from 78.8 to 93.5% and 60.5 to 85.0%, respectively. One of the three SBM evaluated had numerically lower protein digestibility and significantly lower energy digestibility than the other two meals .     

Climate-driven range expansion and morphological evolution in a marine gastropod

Little is known about the phenotypic consequences of global climate change, despite the excellent Pleistocene fossil record of many taxa. We used morphological measurements from extant and Pleistocene populations of a marine gastropod (Acanthinucella spirata) in conjunction with mitochondrial DNA sequence variation from living populations to determine how populations responded phenotypically to Pleistocene climatic changes. Northern populations show little sequence variation as compared to southern populations, a pattern consistent with a recent northward range expansion. These recently recolonized northern populations also contain shell morphologies that are absent in extant southern populations and throughout the Pleistocene fossil record. Thus, contrary to traditional expectations that morphological evolution should occur largely within Pleistocene refugia, our data show that geographical range shifts in response to climatic change can lead to significant morphological evolution.     

A novel method for rearing the progeny of wild mediterranean fruit flies using artificial fruit

A technique for rearing the progeny of wildCeratitis capitata flies was developed. The method is based on wild captured flies which are allowed to oviposit in artificial fruit containing larval rearing medium. Flies develop in the fruit from eggs to last larval instar, then exit the fruit and pupate within vermiculite. This method was shown to be feasible and efficient, and to increase considerably the number of wild flies for testing purposes. Possible contribution to the Sterile Insect Technique (SIT) and potential applications of the method are discussed.     

Effects of the halothane genotype and slaughter weight on texture of pork

The objective of this study was to investigate the effects of the halothane (HAL) genotype, slaughter weight (SW), and the HAL x SW interaction on compositional and textural traits of raw and cooked pork. Pigs were bred to exhibit one of the three HAL genotypes (NN, Nn, and nn) with otherwise equivalent genomes. The nn halothane reactors are known to typically produce PSE pork, whereas NN pigs do not typically produce PSE pork. Pietrain x Large White gilts and boars, all with verified Nn genotype (by DNA test), were mated to obtain F2 littermates of the three HAL genotypes. These pigs were slaughtered at either 101 +/- 3 ("light") or 127 +/- 3 ("heavy") kg BW and were evaluated for longissimus muscle traits. The pH at .5 h after death (pH1) was 6.35, 6.13, and 5.68 in NN, Nn, and nn pigs, respectively. Sarcomere length was greater in nn than in NN and Nn pigs (1.94 vs 1.83 and 1.85 microm, respectively). Mechanical resistance was higher in nn than in NN pigs for both raw and cooked meat. Meat from nn pigs was judged by a trained panel to be less rough, more cohesive, harder, more fibrous, less granular, more elastic, and less easy to swallow than meat from NN pigs. For most traits under study, the heterozygotes were intermediate between the homozygotes but closer to NN than to nn pigs. Muscle from heavy pigs had longer sarcomeres and less moisture than muscle from light pigs. The n allele of the HAL gene unfavorably affects pork texture, and this effect is maintained throughout the range of 101 to 127 kg BW.