Cryopreservation of pig spermatozoa using carboxylated poly-L-lysine as cryoprotectant

In this study, we cryopreserved pig spermatozoa using carboxylated poly-L-lysine (CPLL) as the cryoprotectant to determine its efficacy. Pig spermatozoa were placed in a freezing extender containing 3% (v/v) glycerol and different CPLL concentrations. The motility indices of the spermatozoa cryopreserved with 0.25% (v/v) CPLL at 6 (59.3), 9 (53.7), and 12 (26.2) h after thawing were significantly higher (P < 0.01 or P < 0.05) than those of the spermatozoa cryopreserved without CPLL (53.7, 40.1, and 17.5 at 6, 9, and 12 h after thawing, respectively). The concentration of CPLL in the freezing extender did not affect the ability of frozen-thawed spermatozoa to fertilize oocytes in vitro. However, the blastocyst formation rate of embryos derived from spermatozoa cryopreserved with 0.25% CPLL (24.6%) was significantly higher (P < 0.01) than that of embryos derived from spermatozoa cryopreserved without CPLL (11.2%). The conception rate of the sows inseminated with spermatozoa cryopreserved with 0.25% CPLL (72.2%) was not significantly different from that of the sows inseminated with spermatozoa stored at 17°C (81.3%). However, the mean number of total piglets born to the former (10.0) was significantly lower (P < 0.05) than that of total piglets born to the latter (13.4). The results showed that CPLL in the freezing extender maintained the motility of frozen-thawed pig spermatozoa and improved the in vitro development of embryos produced by in vitro fertilization. In addition, we have demonstrated that piglets could be obtained with artificial insemination using spermatozoa cryopreserved with CPLL.     

Optimization of Phosphorus Fertilizer in Supplemental Feed‐Fed Based Nile Tilapia (Oreochromis niloticus) Ponds

An experiment was conducted in earthen ponds at the Asian Institute of Technology, Thailand to determine different phosphorus fertilizer dose effects on Nile tilapia production, water quality variables, nutrient utilization and cost‐benefit under supplemental feeding. Five phosphorus fertilization rates were used as treatments e.g. 100%, 75%, 50%, 25% and 0% of 7 kg P ha week^?1. Nitrogen fertilization rate was fixed at 28 kg N ha week^?1 for all the treatments. Sex‐reversed Nile tilapia were stocked at 3 fish m^?2, and 30% CP floating feed fed at 50% satiation feeding rate. Nutrient budget showed higher phosphorus fertilizer input resulted in higher phosphorus sink in the sediment. Mean weight, mean weight gain, daily weight gain and net yield were not significantly different among treatments (P > 0.05). Total Kjeldahl nitrogen, total phosphorus and soluble reactive phosphorus were significantly different among treatments. Economic analysis showed phosphorus fertilization resulted in positive net returns. Though the gross income was not affected by different fertilization rates, significantly lowest cost was found in the treatment using 25% phosphorus fertilizer. It can be concluded from the research that 25% phosphorus fertilization might be used as an alternative strategy of Nile tilapia pond culture in terms of economic return and nutrient loss in sediment.     

A major genome region underlying artemisinin resistance in malaria

Evolving resistance to artemisinin-based compounds threatens to derail attempts to control malaria. Resistance has been confirmed in western Cambodia and has recently emerged in western Thailand, but is absent from neighboring Laos. Artemisinin resistance results in reduced parasite clearance rates (CRs) after treatment. We used a two-phase strategy to identify genome region(s) underlying this ongoing selective event. Geographical differentiation and haplotype structure at 6969 polymorphic single-nucleotide polymorphisms (SNPs) in 91 parasites from Cambodia, Thailand, and Laos identified 33 genome regions under strong selection. We screened SNPs and microsatellites within these regions in 715 parasites from Thailand, identifying a selective sweep on chromosome 13 that shows strong association (P = 10(-6) to 10(-12)) with slow CRs, illustrating the efficacy of targeted association for identifying the genetic basis of adaptive traits.     

Estimation of Glomerular Filtration Rate in Normal Sheep by the Disappearance of Iohexol from Serum

Nesje, M., Flåøsyen, A. and Moe, L., 1997. Estimation of glomerular filtration rate in normal sheep by the disappearance of iohexol from serum. Veterinary Research Communications, 21 (1), 29-35. The aim of the study was to establish reference values for glomerular filtration rate (GFR) in healthy sheep from the clearance of iohexol in serum. Fifteen healthy sheep were tested twice with 14 to 21 days between tests. No side-effects were observed after iohexol injections and all the sheep were clinically normal during and after the study. The mean clearance of iohexol estimated by the two-compartment method was 1.8 ml/min per kg (95% CI = 1.6-2.0) in the first trial and 1.7 ml/min per kg (1.5-1.9) in the second trial. The mean GFRiohexol estimated by a one-compartment method was 1.9 ml/min per kg (1.7-2.2) in the first trial and 1.8 ml/min per kg (1.6-2.0) in the second. The GFR values were similar to those reported for the inulin method. The results indicate that the iohexol method is valid for estimating GFR in sheep, and it is easier to perform than the inulin method.     

Nitrate,nutrient content and growth parameters of komatsuna (Brassica rapa L.) in response to manure application depending on EMN (estimated mineralizable nitrogen)

We investigated the effects of poultry manures (PM) and cow manures (CM) using estimated mineralizable nitrogen (EMN) method on nitrate, nutrient content and growth parameters of komatsuna and compared with chemical fertilizer (CF) in an abandoned soil. We applied manures as EMN based on their total N content. The 100% of EMN by PM or CM enhanced dry matter (DM) but depressed nitrate content. The PM-Keifun (PMK) with total N (4.87%) produced greater growth parameters, DM, nutrient content and lower nitrate content but manures with total N (<2%) could not. The solo CF₁₅₀ did not promote leaf number but increased nitrate and Na content. In conclusion, a higher total N (>4%) concentration of manure led to increase availability and nutrient contents, DM, and depressed nitrate content of komatsuna, comparable with solo CF in an abandoned soil.     

Diversity and vertical distribution of indigenous arbuscular mycorrhizal fungi under two soybean rotational systems

To evaluate the importance of arbuscular mycorrhizal fungi (AMF) to crop production, it is imperative to move beyond the plow layer to include the full soil profile impacted by plant roots. To illustrate this, we investigated the vertical distribution of AMF biomass and community structure within the top 100 cm of soil in soybean (Glycine max (L.) Merr., cv: Enrei) rotational systems cropped to wheat (Triticuma estivum L. cv: Bandowase) or left fallow using fatty acid methyl ester (FAME) biomarkers and molecular analysis, respectively. AMF biomass, as measured by concentration of C16:1cis11, declined during fallow and with increasing soil depth. Greater than 50 % of the stored AMF biomass was found at depths below 35 cm. Phylogenetic analysis revealed 16 AMF phylotypes, including nine Glomus, two Gigaspora, two Scutellospora, and one each of Diversispora, Paraglomus, and an unknown glomeromycete, at different sampling depths in this study. Cluster analysis based on the number and abundance of each AMF phylotype formed two distinct clusters separating wheat from fallow rotations. There was no distinct relationship with soil depth beyond clustering AMF communities above and below 20 cm under wheat. Redundancy analysis (RDA) and hierarchical cluster analysis demonstrated that AMF communities by soil depth within each rotation were not significantly different. However, AMF communities were clearly influenced by crop rotation, where the distribution of specific AMF phylotypes responded to the presence of the wheat crop.     

Genetic diversity and population structure of the selected core set in Amaranthus using SSR markers

The genus Amaranthus has gained much attention, particularly for its high economic and nutritional value. It is a genus of taxonomic complexity with many interspecific hybrids. For effective conservation and management of the germplasm collected, the development of a core set of accessions is especially important. A core set of 63 accessions was successfully developed from an entire collection of 634 accessions using the powercore 1.0. Among the tested methods for developing the core set – the advanced M strategy using the modified heuristic method (HCC), randomly chosen collections and stratified random collections – HCC was found to be best, with 100% coverage of alleles and minimum redundancy. Allele frequency distribution of the core set developed with HCC was highly correlated with that of entire collections (r = 0.91). Model‐based structure analysis revealed the presence of three subpopulations and 11 admixtures in the selected core set, which is basically consistent with clustering based on the genetic distance. The results from this study will provide effective information for future germplasm conservation and improvement programmes in Amaranthus.     

Are Droppings,Distance From Pastoralist Camps,and Pika Burrows Good Proxies for Local Grazing Pressure?

Grazing is regarded as one of the most important factors influencing rangeland ecosystems. Many previous studies have used indirect measures (proxies) of grazing intensity, such as the distance from congregation areas and the number of herbivore excreta, to estimate effects of grazing on vegetation parameters in rangeland ecosystems. However, little is known about how such proxies reflect the true grazing intensity, and if their suitability is consistent across landscape conditions. We measured grazing intensity based on the amount of plant ramets being grazed in 75 plots positioned across a rangeland landscape in central Tibet. Several grazing intensity proxies (distance from pastoral camp sites, number of yak dung patches (old and fresh), sheep and goat dropping piles, and pika (Ochotona curzoniae) burrows (active and abandoned)) were also measured in each plot. Regression models were used to examine the suitability of these proxies in predicting our measure of real grazing intensity. None of the examined proxies satisfactorily predicted real grazing intensity in our study system. The distance from camp sites was the best proxy for grazing intensity (P<0.001), but it explained only 30% of its variation. Fresh yak dung and active pika burrows explained only 10% and 3% of the variation in grazing intensity, respectively. The suitability of using proxies for grazing intensity did not significantly differ along landscape parameters (elevation, aspect directions, and slope angle) (P>0.05), except that the number of animal excreta and pika burrows functioned better as proxies at low, compared to high, elevation (P<0.05). Our results should be of concern since many studies use proxies to estimate effects of grazing on vegetation dynamics and ecosystem properties. We recommend awareness of potential limitations and suitability of proxies, when real grazing intensity is not measured.