Effects of soil nutrients and climate factors on belowground biomass in an alpine meadow in the source region of the Yangtze-Yellow rivers, Tibetan Plateau of China

Improving our knowledge of the effects of environmental factors （e.g. soil conditions, precipitation and temperature） on belowground biomass in an alpine grassland is essential for understanding the consequences of carbon storage in this biome. The object of this study is to investigate the relative importance of soil nutrients and climate factors on belowground biomass in an alpine meadow in the source region of the Yangtze and Yellow rivers, Tibetan Plateau. Soil organic carbon （SOC）, total nitrogen （TN） and total phosphorous （TP） contents and belowground biomass were measured at 22 sampling sites across an alpine meadow on the Tibetan Plateau. We analyzed the data by using the redundancy analysis to determine the main environmental factors affecting the belowground biomass and the contribution of each factor. The results showed that SOC, TN and TP were the main factors that influenced belowground biomass, and the contribution of SOC, TN and TP on biomass was in the range of 47.87%-72.06% at soil depths of 0-30 cm. Moreover, the combined contribution of annual mean temperature （AMT） and mean annual precipitation （MAP） on belowground biomass ranged from 0.92% to 4.10%. A potential mechanism for the differences in belowground biomass was caused by the variations in soil nitrogen and phosphorous, which were coupled with SOC. A significant correlation was observed between MAP and soil nutrients （SOC, TN and TP） at the soil depth of 0-10 cm （P〈0.05）. We concluded that precipitation is an important driving force in regulating ecosystem functioning as reflected in variations of soil nutrients （SOC, TN and TP） and dynamics of belowground biomass in alpine grassland ecosystems.

Allele-specific expression and alternative splicing in horse×donkey and cattle×yak hybrids

Divergence of gene expression and alter native splicing is a crucial driving force in the evolution of species;to date, however the molecular mechanism remains unclear. Hybrids of closely related species provide a suitable model to analyze allele-specific expressi on (ASE) and allele-specific alter native splicing (ASS). Analysis of ASE and ASS can uncover the differences in cis-regulatory elements between closely related species, while eliminating interferenee of trans-regulatory elements. Here, we provide a detailed characterization of ASE and ASS from 19 and 10 transcriptome datasets across five tissues from reciprocal-cross hybrids of horsex don key (mule/hi nny) and cattlexyak (dzo), respectively. Results showed that 4.8%-8.7% and 10.8%-16.7% of genes exhibited ASE and ASS, respectively. Notably, IncRNAs and pseudogenes were more likely to show ASE than protein-coding genes. In addition, genes showing ASE and ASS in mule/hinny were found to be involved in the regulation of muscle strength, whereas those of dzo were involved in high-altitude adaptati on. In con clusi on, our study dem on strated that explorati on of genes showing ASE and ASS in hybrids of closely related species is feasible for species evolution research.

Gene expression dynamics during the gonocyte to spermatogonia transition and spermatogenesis in the domestic yak

Background:Spermatogenesis is a cellular differentiation process that includes three major events:mitosis of spermatogonia,meiosis of spermatocytes and spermiogenesis.Steady-state spermatogenesis relies on functions of spermatogonial stem cells(SSCs).Establishing and maintaining a foundational SSC pool is essential for continued spermatogenesis in mammals.Currently,our knowledge about SSC and spermatogenesis is severely limited in domestic animals.Results:In the present study,we examined transcriptomes of testes from domestic yaks at four different stages(3,5,8 and 24 months of age)and attempted to identify genes that are associated with key developmental events of spermatogenesis.Histological analyses showed that the most advanced germ cells within seminiferous tubules of testes from 3,5,8 and 24 months old yaks were gonocytes,spermatogonia,spermatocytes and elongated spermatids,respectively.RNA-sequencing(RNA-seq)analyses revealed that 11904,4381 and 2459 genes were differentially expressed during the gonocyte to spermatogonia transition,the mitosis to meiosis transition and the meiosis to post-meiosis transition.Further analyses identified a list of candidate genes than may regulate these important cellular processes.CXCR4,a previously identified SSC niche factor in mouse,was one of the up-regulated genes in the 5 months old yak testis.Results of immunohistochemical staining confirmed that CXCR4 was exclusively expressed in gonocytes and a subpopulation of spermatogonia in the yak testis.Conclusions:Together,these findings demonstrated histological changes of postnatal testis development in the domestic yak.During development of spermatogonial lineage,meiotic and haploid germ cells are supported by dynamic transcriptional regulation of gene expression.Our transcriptomic analyses provided a list of candidate genes that potentially play crucial roles in directing the establishment of SSC and spermatogenesis in yak.

A comparison of average daily gain,apparent digestibilities,energy balance,rumen fermentation parameters,and serum metabolites between yaks(Bos grunniens)and Qaidam cattle(Bos taurus)consuming diets differing in energy level

Yaks(Bos grunniens),indigenous to the harsh Qinghai-Tibetan Plateau,are well adapted to the severe conditions,and graze natural pasture without supplements all year round.Qaidam cattle(Bos taurus),introduced to the Qinghai-Tibetan Plateau 1,700 years ago,are raised at a lower altitude than yaks,provided with shelter at night and offered supplements in winter.Based on their different backgrounds,we hypothesized that yaks have lower energy requirements for maintenance than cattle.To test this hypothesis,we measured average daily gain(ADG),apparent digestibilities,energy balance,rumen fermentation parameters,and serum metabolites in growing yaks and cattle offered diets differing in metabolizable energy(ME)levels(6.62,8.02,9.42 and 10.80 MJ/kg),but with the same crude protein concentration.Six castrated yaks(155±5.8 kg)and 6 castrated Qaidam cattle(154±8.0 kg),all 2.5 years old,were used in 2 concurrent 4×4 Latin square designs.Neutral and acid detergent fiber digestibilities were greater(P<0.05)in yaks than in cattle,and decreased linearly(P<0.05)with increasing dietary energy level;whereas,digestibilities of dry matter,organic matter,crude protein and ether extract increased(P<0.05)linearly with increasing energy level.The ADG was greater(P<0.001)in yaks than in cattle,and increased(P<0.05)linearly with increasing energy levels.From the regressions of ADG on ME intake,the estimated ME requirement for maintenance was lower(P<0.05)in yaks than in cattle(0.43 vs.0.57 MJ/kg BW0.75).The ratios of digestible energy(DE):gross energy and ME:DE were higher(P<0.05)in yaks than in cattle,and increased(P<0.05)linearly with increasing dietary energy level.Ruminal pH decreased(P<0.05),whereas concentrations of total volatile fatty acids(VFAs)and ammonia increased(P<0.01)with increasing dietary energy level,and all were greater(P<0.05)in yaks than in cattle.Concentrations of ruminal acetate and iso-VFAs were greater(P<0.05),whereas propionate was lower(P<0.05)in yaks than in cattle;acetate decreased(P<0.001),whereas butyrate and propionate increased(P<0.001)linearly with increasing dietary energy level.Serum concentrations ofβ-hydroxybutyrate were lower(interaction,P<0.001)in yaks than in cattle fed diets of 9.42 and 10.80 MJ/kg,whereas non-esterified fatty acids were greater(interaction,P<0.01)in yaks than in cattle fed diets of 6.62 and 8.02 MJ/kg.Concentrations of serum leptin and growth hormone were greater in yaks than in cattle and serum insulin and growth hormone increased(P<0.01)linearly with increasing dietary energy level.Our hypothesis that yaks have lower energy requirements for maintenance than cattle was supported.This lower requirement confers an advantage to yaks over Qaidam cattle in consuming low energy diets during the long winter on the Qinghai-Tibetan Plateau.

The uniqueness and superiority of energy utilization in yaks compared with cattle in the highlands:A review

Yaks living on the Qinghai-Tibetan Plateau for a long time have evolved a series of mechanisms to adapt to the unique geographical environment and climate characteristics of the plateau.Compared with other ruminants,yaks have higher energy utilization and metabolic efficiency.This paper presents possible mechanisms responsible for the efficient energy utilization,absorption and metabolism resulting from the unique evolutionary process of yaks.It is hoped that the information discussed in this review will give a better insight into the uniqueness and superiority of yaks in regards to energy metabolism and utilization compared with cattle and open new avenues for the targeted regulation of energy utilization pathways of other ruminants.

Lasiopodomys fuscus as an important intermediate host for Echinococcus multilocularis:isolation and phylogenetic identification of the parasite

Background:Echinococcus multilocularis causes alveolar echinococcosis(AE)and is widely prevalent in Qinghai Province,China,where a number of different species have been identified as hosts.However,limited information is available on the Qinghai vole(Lasiopodomys fuscus),which is hyper endemic to Qinghai Province and may represent a potential intermediate host of E.multilocularis.Thus,L.fuscus could contribute to the endemicity of AE in the area.Methods:Fifty Qinghai voles were captured from Jigzhi County in Qinghai Province for the clinical identification of E.multilocularis infection via anatomical examination.Hydatid fluid was collected from vesicles of the livers in suspected voles and subjected to a microscopic examination and PCR assay based on the barcoding gene of cox 1.PCR-amplified segments were sequenced for a phylogenetic analysis.E.multilocularis-infected Qinghai voles were morphologically identified and subjected to a phylogenetic analysis to confirm their identities.Results:Seventeen of the 50 Qinghai voles had E.multilocularis-infection-like vesicles in their livers.Eleven out of the 17 Qinghai voles presented E.multilocularis infection,which was detected by PCR and sequencing.The phylogenetic analysis showed that all 11 positive samples belonged to the E.multilocularis Asian genotype.A morphological identification and phylogenetic analysis of the E.multilocularis-infected Qinghai voles confirmed that all captured animals were L.fuscus.Conclusions:L.fuscus can be infected with E.multilocularis and plays a potential role in the life cycle and epidemiology of E.multilocularis in the Qinghai-Tibetan Plateau of China.

Childhood suffering:hyper endemic echinococcosis in Qinghai-Tibetan primary school students,China

Background:As part of an ongoing program that aims to use early detection and timely treatment to improve the control of echinococcosis,especially in younger age groups,we undertook a series of active surveys among Qinghai-Tibetan children in the Qinghai Province of Northwestern China in 2011 and 2012.The significant outcomes that resulted from this study emphasize the need to draw attention to echinococcosis,both alveolar echinococcosis(AE)and cystic echinococcosis(CE),so that policy development is promoted and suitable avenues for control are identified in the highly endemic areas on the Tibetan Plateau.Methods:A total of 19629 primary school students,aged 6-18 years,with a dominant Tibetan background underwent abdominal ultrasound examination,and 86.4%of the compliant students donated 2-5 ml of venous blood for serological tests.All the abnormal ultrasound results were recorded.If identified as echinococcosis,the disease lesion was assessed according to the WHO-Informal Working Group on Echinococcosis(WHO-IWGE)classification for AE and CE.Among the surveyed students,the prevalence by school was compared among geo-locations,sex and age groups.The clinical image presentations were analyzed according to lesion number,size,the location in the liver and the classification stage.Statistical significance was set at P-value<0.05 for comparisons among groups.Results:A total of 341 students(1.7%)were identified by ultrasound as having either CE(119,0.6%)or AE(222,1.1%).The highest prevalence rates of childhood AE cases occurred in the Tehetu(12.1%)and Moba(11.8%)townships in Dari County.There was a high seropositive rate(37.0%)and a heterogeneous distribution of cases,with a prevalence ranged from 0 to 12.1%for AE and 0-2.9%for CE.Moreover,the seropositive rate ranged from 0.7-45.1%across different schools.Conclusions:The high prevalence of echinococcosis in Qinghai-Tibetan primary school students reflects a lack of knowledge about Echinococcus spp.transmission.The combination of systematic education for children and regularly performed anthelmintic treatment for dogs could achieve the goal of sustainable hydatidosis control.