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The interactions between the rumen microbiota and the host are crucial for the digestive and absorptive processes of ruminants, and they are heavily influenced by the climatic conditions of their habitat. Owing to the harsh conditions of the high-altitude habitat, little is known about how ruminants regulate the host transcriptome and the composition of their rumen microbiota. Using the model species of goats, we examined the variations in the rumen microbiota, transcriptome regulation, and climate of the environment between high altitude (Lhasa, Xizang; 3650 m) and low altitude (Chengdu, Sichuan, China; 500 m) goats. The results of 16 S rRNA sequencing revealed variations in the abundance, diversity, and composition of rumen microbiota. Papillibacter, Quinella, and Saccharofermentans were chosen as potential microbes for the adaptation of Xizang goats to the harsh climate of the plateau by the Spearman correlation study of climate and microbiota. Based on rumen transcriptome sequencing analysis, 244 genes were found to be differentially expressed between Xizang goats and low-altitude goats, with 127 genes showing up-regulation and 117 genes showing down-regulation. SLC26A9, GPX3, ARRDC4, and COX1 were identified as potential candidates for plateau adaptation in Xizang goats. Moreover, the metabolism of fatty acids, arachidonic acids, pathway involving cytokines and their receptors could be essential for adaptation to plateau hypoxia and cold endurance. The expression of GPX3, a gene linked to plateau acclimatization in Xizang goats, was linked to the abundance of Anaerovibrio, and the expression of SLC26A9 was linked to the quantity of Selenomonas, according to ruminal microbiota and host Spearman correlation analysis. Our findings imply that in order to adapt harsh plateau conditions, Xizang goats have evolved to maximize digestion and absorption as well as to have a rumen microbiota suitable for the composition of their diet. [ABSTRACT FROM AUTHOR]

Abstract: A paleomagnetic study has been carried out on the Early Cretaceous Zenong Group volcanic rocks (ca. 110–130Ma) near Cuoqin town in the central Lhasa terrane. Stepwise thermal demagnetization up to 680°C isolated a stable high-temperature component (HTC) including antipodal dual polarities. The HTC directions passed both a fold test at 99% confidence and a reversal test at 95% confidence, suggesting a primary origin. The tilt-corrected average direction for 18 sites is D=327.0°, I=35.7°, κ=59.3°, α95 =4.5°, which corresponds to a paleopole at 58.2° N, 341.9° E (A95 =4.6°), yielding a paleolatitude of 19.8°±4.6° N for the study area. Our results, combined with previous paleomagnetic data, suggest that southern Tibet was at a mean paleolatitude of 20° N during the Cretaceous and Paleogene. When compared with the apparent polar wander paths of Asia, the difference suggests that only ca. 870km north–south crustal shortening has accumulated between the Lhasa terrane and stable Asia since ca. 110Ma. When comparing the paleolatitudes of the Lhasa terrane and India, the results indicate that the width of the Neotethys was 6720±690km during the Early Cretaceous. [Copyright &y& Elsevier]

The soil carbon (C) and nitrogen (N) availability are important in the regulation of soil C cycling under climate change. Fertilizers alter soil C and N availability, which can affect C balance. However, the impact of fertilizers on C balance in grassland restoration has been equivocal and warrants more research. We determined the direct and indirect effects of the addition of three levels of C (sucrose) (0, 60, and 120 kg C ha−1 yr−1), three levels of N (urea) (0, 50, and 100 kg N ha−1 yr−1), and a combination of C plus N at each of the levels on soil respiration (Rs) dynamics and C balance in an alpine meadow in northern Tibet (4700 m above sea level). This study was undertaken during the middle of the growing season in 2011–2012. The addition of C and/or N stimulated CO 2 emission, which was 2-fold greater in 2011 (102–144 g C m−2) than in 2012 (43–54 g C m−2). The rate of Rs increased with the addition of N, but was not affected with the addition of C plus N. Microbial biomass C, dissolved organic C and inorganic N were the main drivers of Rs. We concluded that N addition stimulated Rs to a greater extent than C addition in the short term. The application of fertilizer in the restoration of degraded grassland should be re-considered. • Soil microbial content was the main driver of soil respiration (Rs). • N availability stimulated Rs to a greater extent than C availability. • The addition of C and/or N stimulated CO 2 emission by less than 31%. • The addition of C and/or N had no effect on C sequestration. [ABSTRACT FROM AUTHOR]

• N uptake by grasses was greater than sedges and forbs in fenced plots. • 15N recovery in fenced plots increased in top but decreased in sub-surface soil. • More N was allocated to roots than shoots in nutrient-poor soil (grazed) plots. • More N was allocated to shoots than roots in nutrient-rich soil (fenced) plots. • The root:shoot ratio in 15N was greater in grazed than fenced plots. The grasslands of Qinghai-Tibetan Plateau have become extremely degraded, resulting in widespread deficiency of soil N. In efforts to restore degraded lands, fencing enclosure has been used extensively. However, the effect of fencing on N allocation patterns and nutritional strategy of alpine plants are equivocal. In this study, we used 15N tracer (CO (15NH 2) 2 , 10 g N m−2) to examine the allocation and distribution of N in plants and soil in grasslands either grazed heavily by livestock or fenced for three years in an alpine meadow of Northern Tibet. The 15N recovery (15N rec) in shoots of the fenced enclosure increased by 207% in grasses, decreased by 103% in forbs, and did not change in sedges when compared to the grazed meadow. The 15N rec in shoots accounted for only 1.97% and 4.65% of the total N in the grazed and fenced meadows, respectively. Fencing increased soil 15N content at 0–5 cm depth by 6.9%, but decreased the content at 5–10 cm depth by 11.7%. The results demonstrated that fencing altered the soil N distribution by increasing 15N rec in top soil and by decreasing 15N rec in subsurface soil. In addition, fencing had no impact on root 15N storage (33%–39%), 15N losses (9.6%–12.5%) and soil available 15N rec (NH 4 +-N, NO 3 –-N and light fraction organic N), but decreased root:shoot 15N rec ratio by 49.8% (16.9:1 in grazed and 8.4:1 in fenced grassland). Fencing increased soil organic carbon, total N and NO 3 –-N concentrations, which indicated that the strategy of the plants was to allocate relatively more N to roots in nutrient-poor soil (grazed) but relatively more N to shoots in nutrient-rich soil (fenced). [ABSTRACT FROM AUTHOR]