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The mode of human immunodeficiency virus (HIV) transmission via injection drug use (IDU) still exists, and the recent shift in IDU-related transmission of HIV infection is largely unknown. The purpose of this study was to analyze the spatiotemporal sources and dynamics of HIV-1 transmission through IDU in Guangxi. We performed a molecular epidemiological investigation of infections across Guangxi from 2009 to 2019. Phylogenetic and Bayesian time-geographic analyses of HIV-1 sequences were performed to confirm the characteristics of transmission between IDUs in combination with epidemiological data. Among the 535 subjects, CRF08_BC (57.4%), CRF01_AE (28.4%), and CRF07_BC (10.7%) were the top 3 HIV strains; 72.6% of infections were linked to other provinces in the transmission network; 93.6% of sequence-transmitted strains were locally endemic, with the rest coming from other provinces, predominantly Guangdong and Yunnan; 92.1% of the HIV transmission among people who inject drugs tended to be transmitted between HIV-positive IDUs. HIV recombinants were high diversity, and circulating local strains were the transmission sources among IDUs in Guangxi. However, there were still cases of IDUs linked to other provinces. Coverage of traditional prevention strategies should be expanded, and inter-provincial collaboration between Guangxi, Yunnan, and Guangdong provinces should be strengthened. [ABSTRACT FROM AUTHOR]

This paper uses pollen analysis to investigate and document the changing climate and vegetation during the Holocene based on a 400 cm core in depth obtained at a wetland site at Haligu (3,277 m a. s. l.) on the Jade Dragon Snow Mountain in Yunnan, China. By applying the Coexistence Approach to pollen data from this core, a quantitative reconstruction of climate over the last 9,300 years was made based on each pollen zone and individual core sample, which reveals the temperature and precipitation change frequently during that time. The qualitative analyses show that from 9300 to 8700 cal. yr BP, the vegetation was dominated by needle-leaved forest (mainly Pinus and Abies), indicating a slightly cool and moderately humid climate. Between 8700 and 7000 cal. yr BP, evergreen broad-leaved forest, dominated by Quercus, became the predominant vegetation type, replacing needle-leaved forest at this elevation, implying a warmer and more humid climate. During the period 7000 to 4000 cal. yr BP, the vegetation changed to mixed needle-leaved and evergreen broad-leaved forest, indicating a warm and moderately humid climate, but somewhat cooler than the preceding stage. From 4000 to 2400 cal. yr BP, the vegetation was again dominated by evergreen broad-leaved forest, but coniferous trees (mainly Pinus) began to increase, especially relative to a decline in Quercus. This implies that the climate remained warm and humid but slight drier than previously. The evergreen Quercus phase (8700-2400 yr BP) was designated as the Holocene climatic optimum in the Haligu core sediments. It is correlated with a markedly greater abundance and diversity of pteridophytes spores than was recorded before or after this period. From 2400 cal. yr BP to present, the vegetation was dominated by needle-leaved forest, of which Pinus formed the predominant component, accompanied by Abies and Tsuga. This reflects a slightly cooler, humid climate but also correlates with a period of increasing human settlement on the lower slopes of the mountain. At this elevated site, several hundred metres above the highest present day settlements, direct palynological evidence of anthropogenic activity is uncertain but we discuss ways in which the marked decline in Quercus pollen during this period may reflect the impact of ways in which natural resources of the mountain have been utilised. [ABSTRACT FROM AUTHOR]

Yuanmou Basin of Yunnan, SW China, is a famous locality with hominids, hominoids, mammals and plant fossils. Based on the published megaflora and palynoflora data from Yuanmou Basin, the climate of Late Pliocene is reconstructed using the Coexistence Approach. The results indicate a warm and humid subtropical climate with a mean annual temperature of ca. 16-17°C and a mean annual precipitation of ca. 1500-1600 mm in the Late Pliocene rather than a dry, hot climate today, which may be due to the local tectonic change and gradual intensification of India monsoon. The comparison of Late Pliocene climate in Eryuan, Yangyi, Longling, and Yuanmou Basin of Yunnan Province suggests that the mean annual temperatures generally show a latitudinal gradient and fit well with their geographic position, while the mean annual precipitations seem to be related to the different geometries of the valleys under the same monsoon system. [ABSTRACT FROM AUTHOR]

The Younger Dryas (YD) is the most recent abrupt climatic event recognized during the transition from the last glaciation to the Holocene. Growing evidence from the middle and high latitudes of Europe and North America shows that the climate within the YD event was highly unstable. Until recently, however, climate instability during this event has received little attention elsewhere in the world. Here we present evidence of a climatically unstable YD based on pollen-climate transfer function and REDFIT spectral analysis of pollen data from Haligu in the Hengduan Mountains of southwestern China, a low latitude temperate biodiversity hotspot. Our data show that the climate fluctuated significantly during the YD, with three warm peaks recognized at 11.5, 11.7 and 12.3 cal kyr BP. In particular, we estimate a gradual rise in mean annual temperature by 3.7 °C between the end of the YD and the early Holocene (11.2–10.9 cal kyr BP). In response to this, the subalpine conifer forest dominated by Picea and Abies may have migrated about 610 m upwards. We also detected that the climate fluctuations during the YD-Holocene transition show significant centennial periodicities of 76 yr, 84 yr, 91 yr, 95 yr, and 638 yr. The former four cycles are possibly related to the Gleissberg (around 80 yr) solar cycle, which was also detected in the Hongyuan peat, the PC-6 core of the East China Sea and the GISP2 ice core. These new findings enhance our understanding of millennial-scale abrupt climate events which may be of great significance in predicting the impact of future climate change on mountainous ecosystems in southwestern China. The warming at the end of the YD may provide a potential analog for global warming in the near future, during which the upward migration of vegetation zones will likely lead to the loss of habitat for threatened species. We therefore should take action to restore habitats and provide protected areas for species at risk. Unlabelled Image • Three warm peaks during the YD interval were recognized in the Hengduan Mountains. • Climate fluctuations during the YD-Holocene transition show significant periodicities. • Subalpine conifer forest migrated about 610 m upwards at the YD-Holocene transition. [ABSTRACT FROM AUTHOR]

Abstract: Psaronius housuoensis sp. nov. is described from the Upper Permian Xuanwei Formation deposits of Housuo Coal Mine, Fuyuan County, Yunnan Province, southwest China, adding to the marattialean fern community of the Cathaysian flora. The permineralized stem shows a polycyclic dictyostele with five leaf traces arranged in a helical manner and exhibiting 2/5 phyllotaxy. Vascular bundles arranged in 6 concentric rings with cauline bundles in 5 radial rows. Stem bound externally by a peripheral sclerenchyma sheath. Leaf trace configuration comprised of three vascular bundles resulting from the division of a single originally C-shaped strand. Ground tissue replaced with coprolites and sediments. Stem surrounded by a thick mantle of roots. Occurrence of coprolites within the stem indicates well developed plant–animal interaction during the Late Permian times and that the habitat in which Psaronius grew was abounding with diversity of arthropod or the oribatid mite community preferring the rotting P. housuoensis sp. nov. stem ground tissue as a suitable microenvironment for shelter. Evolutionary pattern of leaf trace development is described in the new species and its possible ecological significance. [ABSTRACT FROM AUTHOR]

The Hengduan Mountains of Southwest China are considered the most biologically diverse temperate ecosystem in the world. Here, we present a ~ 10,000-year pollen record from Shuanghaizi Lake, northwestern Yunnan, which we use to reconstruct vegetation dynamics, climatic fluctuations and variability in the Indian Summer Monsoon (ISM). The results suggest that, between 10,000 and 7900 cal. yr BP, vegetation comprised mainly mixed needle- and broad-leaved forest (mostly Abies , Pinus , Quercus , and Salix), indicating a warm and humid climate, corresponding to a strong ISM. From 7900 to 6900 cal. yr BP, the mixed needle- and broad-leaved forest persisted, while an increase in Abies pollen and decrease in pollen of Pinus and Salix implies a reduction in temperature and precipitation, suggesting a slightly weaker ISM than in the preceding phase. Between 6900 and 2400 cal. yr BP, an expansion of Pinus and Quercus in mixed needle- and broad-leaved forest, together with the first occurrence of the aquatic Potamogeton , suggest a warmer and more humid climate, likely due to the strengthening monsoon, consistent with the Holocene climatic optimum. From 2400 to 970 cal. yr BP, the vegetation shifted to needle-leaved forest with sparse patches of broad-leaved forest, concurrent with a weakening ISM through the middle of this period. During the first half of the period covering 970 to 470 cal. yr BP, Abies and Picea increased and we inferred the lowest temperature and precipitation of the whole study, implying the weakest ISM. In the middle of this period, an expansion of broad-leaved trees including Quercus , Alnus , Betula and Castanopsis plus diverse herbaceous plants suggests that the climate developed towards warmer and more humid conditions, in agreement with a gradual intensification of the ISM. After 470 cal. yr BP, the vegetation became dominated by needle-leaved forest and most broad-leaved elements became intermittent. Although the climate was generally cool and dry in this period, temperature and precipitation gradually increased compared with the previous stage, indicating a slight intensification of the ISM. These findings provide a more detailed understanding of Holocene vegetation dynamics, climatic change, and the evolution of the palaeomonsoon in the Hengduan Mountains biodiversity hotspot, southwestern China. Unlabelled Image • Pollen record reflects Holocene vegetation dynamics and climate history in SW China • Quantitative climatic data reveal the fluctuations of temperature and precipitation in the Holocene • Changes in summer solar insolation at 30° N may have triggered Holocene variability in ISM intensity [ABSTRACT FROM AUTHOR]