Comparison of Intestinal Microbiota of Blue Fox before and after Weaning.

Intestinal flora plays an important role in maintaining the internal stability and health of the intestine. Currently, intestinal microbes are considered an important "organ" but are mostly ignored by people. This study evaluated the flora structure of each intestinal segment of blue foxes pre-weaning and explored the differences between the fecal flora and intestinal flora structure of each segment after weaning. Samples of intestinal contents from three blue foxes at 45 days of age (before weaning) and intestinal contents and feces samples from at 80 days (after weaning) were collected for 16s rRNA flora analysis. The species and distribution characteristics of microorganisms in different intestinal segments of blue foxes before and after weaning were different. Except for the rectum, the dominant flora of each intestinal segment of blue fox changed significantly after experiencing weaning, and the fecal flora structure of young fox at the weaning stage did not represent the whole intestinal flora structure but was highly similar to that of the colon and rectum. To sum up, the intestinal flora of blue foxes changed systematically before and after weaning. When performing non-invasive experiments, the microflora structure of the colon and rectum of blue foxes can be predicted by collecting fecal samples.

Hotspots of riverine greenhouse gas (CH4, CO2, N2O) emissions from Qinghai Lake Basin on the northeast Tibetan Plateau.

Evasion of greenhouse gases (GHG) from fluvial systems is now recognized as a significant component of the global carbon cycle. However, the magnitudes of GHG fluxes remain uncertain due to limited research data, especially on the Tibetan Plateau. In this study Methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O) concentrations were measured and their diffusive fluxes were estimated by headspace-gas chromatography in two rivers basins (Buha and Shaliu rivers) on the Northeast Tibetan Plateau during three seasons from October 2020 to August 2021. The results showed that the focal rivers on the Tibetan Plateau are potentially important sources of GHG. Both rivers have higher GHG concentrations and diffusion flux during the snowmelt period than other seasons. In general, GHG diffusion fluxes in the Buha river were higher than those in the Shaliu river and their concentrations are higher in the upstream region than in the downstream region of both basins. The salinity in water and wind spread were found to be important factors influencing in GHGs diffusion fluxes. While diffusive fluxes of GHG in rivers were a small component of watershed-scale fluvial Carbon gas efflux compared to other studies, these fluxes will likely increase as thaw slump occurrence. Overall, this study highlights that better recognition of the influence that river networks have on global warming is required-especially when it comes to high-elevation rivers across permafrost, as permafrost will continue to thaw as climate warming.

Requirements and Metabolism for Calcium, Phosphorus and Vitamin D3 in the Growing-Furring Blue Foxes.

A 3 × 3 factorial experiment was conducted to investigate the influence of dietary calcium, phosphorus, and vitamin D3 (VD3) supplement levels on the growth performance, nutrient digestibility, and serum biochemical indices of growing-furring blue foxes. One hundred and thirty-five 120-day-old male blue foxes were randomly allocated into nine groups. The nine treatment diets were supplemented with 0%, 0.4%, or 0.8% Ca, and 1000, 2000, or 4000 IU·kg−1 VD3. The base diet contained 0.8% Ca and 327 IU·kg−1 VD3. The dietary calcium level had a significant effect on the average daily gain (ADG) of blue foxes at 121 to 135 days of age and 136 to 150 days (p < 0.05). The ADG of blue foxes at 121 to 135 days of age was significantly decreased by VD3 level (p < 0.05). The Ca dosage decreased the nutrient digestibility (p < 0.05). The Ca dosage increased the fecal Ca and P and decreased the P digestibility (p < 0.05). Interactions were found between the Ca and VD3 levels, which affected the digestibility of Ca and P (p < 0.05). In conclusion, this research determined the suitable doses of Ca and VD3 for growing-furring blue foxes.

Testicular Transcriptome of Males and Pseudo-Males Provides Important New Insight into Sex Reversal of Rana dybowskii.

Rana dybowskii (R. dybowskii) is an ecological species found in China, Japan, Korea, and Russia. Like most amphibians, R. dybowskii lacks heterotypic sex chromosomes, limiting the in-depth study of sex determination and sex reversal mechanisms. Previous studies have shown that certain environmental factors can modify R. dybowskii genotypic females into phenotypic males, but the mechanism is still unknown. Considering the difficulties in identifying and collecting sex reversal gonads at different stages of differentiation under natural conditions, testes from sexually mature wild adult R. dybowskii were taken in this study, and the genotypic sex of individuals and sex reversal were identified by two male-linked genetic markers reported in our most recent findings. Transcriptome sequencing was performed on testicular tissue from males and pseudo-males, as well as female ovary tissue. The results show that the gene expression patterns of pseudo-males' testes were similar to those of the males but highly differed from females' ovaries. One hundred and seventeen differentially expressed genes between testes of pseudo-males and males were found, and the up-regulation of doublesex and mab-3 related transcription factor 1 (Dmrt1) in testes of pseudo-males may play a key role in R. dybowskii sex reversal.

Episodes of Early Pleistocene West Antarctic Ice Sheet Retreat Recorded by Iceberg Alley Sediments.

Ice loss in the Southern Hemisphere has been greatest over the past 30 years in West Antarctica. The high sensitivity of this region to climate change has motivated geologists to examine marine sedimentary records for evidence of past episodes of West Antarctic Ice Sheet (WAIS) instability. Sediments accumulating in the Scotia Sea are useful to examine for this purpose because they receive iceberg-rafted debris (IBRD) sourced from the Pacific- and Atlantic-facing sectors of West Antarctica. Here we report on the sedimentology and provenance of the oldest of three cm-scale coarse-grained layers recovered from this sea at International Ocean Discovery Program Site U1538. These layers are preserved in opal-rich sediments deposited ∼1.2 Ma during a relatively warm regional climate. Our microCT-based analysis of the layer's in-situ fabric confirms its ice-rafted origin. We further infer that it is the product of an intense but short-lived episode of IBRD deposition. Based on the petrography of its sand fraction and the Phanerozoic 40Ar/39Ar ages of hornblende and mica it contains, we conclude that the IBRD it contains was likely sourced from the Weddell Sea and/or Amundsen Sea embayment(s) of West Antarctica. We attribute the high concentrations of IBRD in these layers to "dirty" icebergs calved from the WAIS following its retreat inland from its modern grounding line. These layers also sit at the top of a ∼366-m thick Pliocene and early Pleistocene sequence that is much more dropstone-rich than its overlying sediments. We speculate this fact may reflect that WAIS mass-balance was highly dynamic during the ∼41-kyr (inter)glacial world.

Ancient marine sediment DNA reveals diatom transition in Antarctica.

Antarctica is one of the most vulnerable regions to climate change on Earth and studying the past and present responses of this polar marine ecosystem to environmental change is a matter of urgency. Sedimentary ancient DNA (sedaDNA) analysis can provide such insights into past ecosystem-wide changes. Here we present authenticated (through extensive contamination control and sedaDNA damage analysis) metagenomic marine eukaryote sedaDNA from the Scotia Sea region acquired during IODP Expedition 382. We also provide a marine eukaryote sedaDNA record of ~1 Mio. years and diatom and chlorophyte sedaDNA dating back to ~540 ka (using taxonomic marker genes SSU, LSU, psbO). We find evidence of warm phases being associated with high relative diatom abundance, and a marked transition from diatoms comprising <10% of all eukaryotes prior to ~14.5 ka, to ~50% after this time, i.e., following Meltwater Pulse 1A, alongside a composition change from sea-ice to open-ocean species. Our study demonstrates that sedaDNA tools can be expanded to hundreds of thousands of years, opening the pathway to the study of ecosystem-wide marine shifts and paleo-productivity phases throughout multiple glacial-interglacial cycles.

The Role of Thermokarst Lake Expansion in Altering the Microbial Community and Methane Cycling in Beiluhe Basin on Tibetan Plateau.

One of the most significant environmental changes across the Tibetan Plateau (TP) is the rapid lake expansion. The expansion of thermokarst lakes affects the global biogeochemical cycles and local climate regulation by rising levels, expanding area, and increasing water volumes. Meanwhile, microbial activity contributes greatly to the biogeochemical cycle of carbon in the thermokarst lakes, including organic matter decomposition, soil formation, and mineralization. However, the impact of lake expansion on distribution patterns of microbial communities and methane cycling, especially those of water and sediment under ice, remain unknown. This hinders our ability to assess the true impact of lake expansion on ecosystem services and our ability to accurately investigate greenhouse gas emissions and consumption in thermokarst lakes. Here, we explored the patterns of microorganisms and methane cycling by investigating sediment and water samples at an oriented direction of expansion occurred from four points under ice of a mature-developed thermokarst lake on TP. In addition, the methane concentration of each water layer was examined. Microbial diversity and network complexity were different in our shallow points (MS, SH) and deep points (CE, SH). There are differences of microbial community composition among four points, resulting in the decreased relative abundances of dominant phyla, such as Firmicutes in sediment, Proteobacteria in water, Thermoplasmatota in sediment and water, and increased relative abundance of Actinobacteriota with MS and SH points. Microbial community composition involved in methane cycling also shifted, such as increases in USCγ, Methylomonas, and Methylobacter, with higher relative abundance consistent with low dissolved methane concentration in MS and SH points. There was a strong correlation between changes in microbiota characteristics and changes in water and sediment environmental factors. Together, these results show that lake expansion has an important impact on microbial diversity and methane cycling.

Effect of Dietary Supplementation with Calcium, Phosphorus and Vitamin D3 on Growth Performance, Nutrient Digestibility, and Serum Biochemical Parameters of Growing Blue Foxes.

Based on the randomized design, a 3 × 3 factorial experiment was designed to examine the effects of dietary calcium (Ca), phosphorus (P), and vitamin D3 (VD3) supplemental levels with a fixed 1.5/1 ratio of Ca to P on the growth performance, nutrient digestibility, and serum biochemical indices blue foxes' growth. In total, 135 male blue foxes with the age of 60 days were randomly divided into 9 groups each with 15 blue foxes. The blue foxes belonging to the nine treatment groups were fed Ca supplementation (0%, 0.4%, or 0.8%) and VD3 supplementation (1000, 2000, or 4000 IU/kg DM). The base diet contained 0.8% Ca and 327 IU/kg VD3. The dosage of VD3 in blue foxes showed a significant impact on their growth performance (p < 0.05). The Ca dosage had a linear effect on the digestibility of the CP and carbohydrates (CHO) (p < 0.05). In conclusion, the results indicated that the Ca and VD3 doses showed promising effects on growth performance and nutrient digestibility in growing blue foxes and could reduce fecal N and P via improvement in protein and P utilization.

Antiphased dust deposition and productivity in the Antarctic Zone over 1.5 million years.

The Southern Ocean paleoceanography provides key insights into how iron fertilization and oceanic productivity developed through Pleistocene ice-ages and their role in influencing the carbon cycle. We report a high-resolution record of dust deposition and ocean productivity for the Antarctic Zone, close to the main dust source, Patagonia. Our deep-ocean records cover the last 1.5 Ma, thus doubling that from Antarctic ice-cores. We find a 5 to 15-fold increase in dust deposition during glacials and a 2 to 5-fold increase in biogenic silica deposition, reflecting higher ocean productivity during interglacials. This antiphasing persisted throughout the last 25 glacial cycles. Dust deposition became more pronounced across the Mid-Pleistocene Transition (MPT) in the Southern Hemisphere, with an abrupt shift suggesting more severe glaciations since ~0.9 Ma. Productivity was intermediate pre-MPT, lowest during the MPT and highest since 0.4 Ma. Generally, glacials experienced extended sea-ice cover, reduced bottom-water export and Weddell Gyre dynamics, which helped lower atmospheric CO2 levels.

Sedimentary organic carbon storage of thermokarst lakes and ponds across Tibetan permafrost region.

Sedimentary soil organic carbon (SOC) stored in thermokarst lakes and ponds (hereafter referred to as thaw lakes) across high-latitude/altitude permafrost areas is of global significance due to increasing thaw lake numbers and their high C vulnerability under climate warming. However, to date, little is known about the SOC storage in these lakes, which limits our better understanding of the fate of these active carbon in a warming future. Here, by combining large-scale field observation data and published deep (e.g., 0-300 cm) permafrost SOC data with a random forest (RF) machine learning technique, we provided the first comprehensive estimation of thaw lake SOC stocks to 3 m depth on the Tibetan Plateau. This study demonstrated that combining multiple environmental factors with the RF model could effectively predict the spatial distributions of the thaw lake SOC density values (SOCDs). The model results revealed that the soil respiration, normalized difference vegetation index (NDVI), and mean annual precipitation (MAP) were the most influential factors for predicting thaw lake SOCDs. In total, the sedimentary SOC stocks in the thaw lakes were approximately 52.62 Tg in the top 3 m, with 53% of the SOC stored in the upper layers (0-100 cm). The SOCDs generally exhibited high values in eastern Tibetan Plateau, and low values in mid- and western Tibetan Plateau, which were similar to the patterns of the land cover types that affected the SOCDs. We further found that the SOCDs of thaw lakes were generally higher than those of their surrounding permafrost soils at different layer depths, which could be ascribed to the erosion of soil particles or leaching solution from the thawing permafrost soils to lakes and/or enhanced vegetation growth at the lake bottom. This research highlights the necessity of explicitly considering the thaw lake SOC stocks in Earth system models for more comprehensive future projections of the carbon dynamics on the plateau.

Male heterogametic sex determination in Rana dybowskii based on sex-linked molecular markers.

Identifying the mechanism for sex determination in amphibians is challenging. Very little is known about sex determination mechanisms of Rana dybowskii, a species of importance to evolutionary and conservation biology. We screened for sex-linked molecular markers in R. dybowskii in China using target region amplification polymorphism with 2 fixed primers against the sequences of Dmrt1. We found 2 male-linked molecular markers in R. dybowskii, which were 222 bp and 261 bp long. The detection rates of 222 bp marker in males form Xinglong, Huadian, and Dandong were 93.79%, 69.64%, and 13.64%, respectively, while the rate in females from Huadian was 27.50%. Besides, the detection rates of 261 bp marker in the above 3 regions were only observed in males at the rate of 93.79%, 87.50%, and 32.73%, respectively. The inheritance patterns of sex-linked molecular markers showed that the 2 sex-linked molecular markers were heterozygous. Compared to the XY-male parent, progeny from XX-pseudo-male parent possessed lower sex reversal ratio at the same rearing temperature, and the proportion of female froglets from an XX-pseudo-male parent was more than 95% at low rearing temperature (15°C). Our findings suggest that R. dybowskii displays male heterogamety, and the 2 sex-linked molecular markers may have a guiding significance for the protection and utilization of R. dybowskii.

Iron in the NEEM ice core relative to Asian loess records over the last glacial-interglacial cycle.

Mineral dust can indirectly affect the climate by supplying bioavailable iron (Fe) to the ocean. Here, we present the records of dissolved Fe (DFe) and total Fe (TDFe) in North Greenland Eemian Ice Drilling (NEEM) ice core over the past 110 kyr BP. The Fe records are significantly negatively correlated with the carbon-dioxide (CO2) concentrations during cold periods. The results suggest that the changes in Fe fluxes over the past 110 kyr BP in the NEEM ice core are consistent with those in Chinese loess records because the mineral-dust distribution is controlled by the East Asian deserts. Furthermore, the variations in the dust input on a global scale are most likely driven by changes in solar radiation during the last glacial-interglacial cycle in response to Earth's orbital cycles. In the last glacial-interglacial cycle, the DFe/TDFe ratios were higher during the warm periods (following the post-Industrial Revolution and during the Holocene and last interglacial period) than during the main cold period (i.e. the last glacial maximum (LGM)), indicating that the aeolian input of iron and the iron fertilization effect on the oceans have a non-linear relationship during different periods. Although the burning of biomass aerosols has released large amounts of DFe since the Industrial Revolution, no significant responses are observed in the DFe and TDFe variations during this period, indicating that severe anthropogenic contamination has no significant effect on the DFe (TDFe) release in the NEEM ice core.

High methane emissions from thermokarst lakes on the Tibetan Plateau are largely attributed to ebullition fluxes.

Ebullition has been shown to be an important pathway for methane (CH4) emissions from inland waters. However, the CH4 fluxes and their magnitudes in thermokarst lakes remain unclear due to limited research data, especially on the Tibetan Plateau (TP). The magnitude and regulation of two CH4 pathways, ebullition and diffusion, were investigated in 32 thermokarst lakes on the TP during the summer of 2020. CH4 emissions from thermokarst lakes on the TP showed significant spatiotemporal heterogeneity. Diffusion fluxes in lakes averaged 2.6 mmol m-2 d-1 (ranging from 0.003 to 48.4 mmol m-2 d-1), and ebullition fluxes in lakes averaged 6.6 mmol CH4 m-2 d-1 (ranging from 0.002 to 140.0 mmol m-2 d-1). Together, these ebullition fluxes contributed 66.1 ± 24.9% (ranging 5.4 to 100.0%) to the total (diffusion + ebullition) CH4 emissions, indicating the importance of ebullition as a major CH4 transport mechanism on the TP. In general, thermokarst lakes with higher CH4 diffusion fluxes and ebullition fluxes occurred in alpine meadows (2.5 ± 5.3 mmol m-2 d-1; 8.2 ± 20.6 mmol m-2 d-1), followed by alpine steppes (0.6 ± 5.3 mmol m-2 d-1; 0.7 ± 10.8 mmol m-2 d-1) and desert steppes (0.2 ± 0.2 mmol m-2 d-1; 0.6 ± 0.8 mmol m-2 d-1). The organic matter contents in water and sediment were found to be important factors influencing the seasonal variations in CH4 diffusion fluxes. However, the ebullition CH4 fluxes did not show a clear seasonal variation pattern. Our findings highlight the importance of considering the large spatiotemporal variations in ebullition CH4 fluxes to improve the accuracy of large-scale estimations of CH4 fluxes in thermokarst lakes on the TP. Greater insight into these aspects will increase the understanding of CH4 dynamics in thermokarst lakes on the TP, which is essential for forecasting and climate impact assessments and to better constrain feedback to climate warming.

Seasonal Variation of Mercury and Its Isotopes in Atmospheric Particles at the Coastal Zhongshan Station, Eastern Antarctica.

Mercury (Hg) is a globally spread trace metal due to its long atmospheric residence time. Yet, our understanding of atmospheric processes (e.g., redox reactions and deposition) driving Hg cycling is still limited, especially in polar regions. The Antarctic continent, by virtue of its remoteness, is the perfect location to investigate Hg atmospheric processes in the absence of significant local anthropogenic impact. Here, we present the first 2 year record (2016-2017) of total suspended particulate mercury (PHg) concentrations along with a year-round determination of an Hg stable isotopic composition in particles collected at Zhongshan Station (ZSS), eastern Antarctic coast. The mean PHg concentration is 21.8 ± 32.1 pg/m3, ranging from 0.9 to 195.6 pg/m3, and peaks in spring and summer. The negative mass-independent fractionation of odd Hg isotopes (odd-MIF, average -0.38 ± 0.12‰ for Δ199Hg) and the slope of Δ199Hg/Δ201Hg with 0.91 ± 0.12 suggest that the springtime isotope variation of PHg is likely caused by in situ photo-oxidation and reduction reactions. On the other hand, the increase of PHg concentrations and the observed odd-MIF values in summer are attributed to the transport by katabatic winds of divalent species derived from the oxidation of elemental Hg in the inland Antarctic Plateau.

The iron records and its sources during 1990-2017 from the Lambert Glacial Basin shallow ice core, East Antarctica.

In this study, a shallow ice core (12.5 m, called LGB) was drilled at the Lambert Glacial Basin, East Antarctica. The major ion and metal elements were measured at 5-6 cm resolution in this shallow core, which covered the period 1990-2017. Therefore, an annual-resolution record of iron (Fe) concentrations and fluxes were reconstructed in this shallow ice core. Although the Fe data is comparable to previous results, our results emphasized that much more dissolved Fe (DFe) from the Cerro Hudson volcanic event (August 1991) was transported to the East Antarctic ice sheet, in comparison with the Pinatubo volcanic event (June 1991). The aeolian dust may be the primary DFe source during 1990-2017. In particular, the DFe variations may be affected by the biomass burning emissions in two periods (1990-1998 and 2014-2017). While total dissolved Fe (TDFe) variations were controlled by the climatic conditions since 2000 because of the temperature (δ18O) decreasing at East Antarctica. These Fe data will be useful to assess the modern bioavailable Fe release for the Antarctica ice sheet.

A 300-Year High-Resolution Greenland Ice Record of Large-Scale Atmospheric Pollution by Arsenic in the Northern Hemisphere.

We report the first high-resolution record of arsenic (As) observed in Greenland snow and ice for the periods 1711-1970 and 2003-2009 AD. The results show well-defined large-scale atmospheric pollution by this toxic element in the northern hemisphere, beginning as early as the 18th century. The most striking feature is an abrupt, unprecedented enrichment factor (EF) peak in the late 1890s, with an ∼30-fold increase in the mean value above the Holocene natural level. Highly enriched As was evident until the late 1910s; a sharp decline was observed after the First World War, reaching a minimum in the early 1930s during the Great Depression. A subsequent increase lasted until the mid-1950s, before decreasing again. Comparisons between the observed variations and Cu smelting data indicate that Cu smelting in Europe and North America was the likely source of early anthropogenic As in Greenland. Despite a significant reduction of ∼80% in concentration and ∼60% in EF from the 1950s to the 2000s, more than 80% of present-day As in Greenland is of anthropogenic origin, probably due to increasing As emissions from coal combustion in China. This highlights the demand for the implementation of national and international environmental regulations to further reduce As emissions.

Dust provenance in Pan-third pole modern glacierized regions: What is the regional source?

To differentiate the source of aeolian dust between the desert sources from Pan-third pole and high mountain glaciers, therefore, we investigated the spatial variability of aeolian dust sources in the Pan-third polar region. The question of whether such changes reflect variable transport pathways from a unique source in the western China area was addressed. That is, the SrNd radiogenic isotope composition of modern desert samples do not support the hypothesis of a single dust provenance at higher elevation mountain glaciers by long-distance transport; regional sources also play a significant role. Based on previous studies and the data from this study, the five isotopic regions were divided, which are controlled by the geological characteristics in western China. The results suggest that mineral dust deposited into the high-mountain glaciers originated from the free ice region because of glacier melting and the physical and chemical erosion of rocks from the surrounding mountains by local wind systems. The Pb isotopic data further demonstrated that natural dust is the source of Pb for the high-mountain glaciers of Pan-third pole. These results provide an exhaustive documentation of the isotopic signature of the regional dust reaching the glacier regions.

Fe variation characteristics and sources in snow samples along a traverse from Zhongshan Station to Dome A, East Antarctica.

Iron concentrations in the Southern Ocean are thought to act as a driver of the regular glacial-interglacial cycles in atmospheric carbon dioxide (CO2). This study presents the concentrations of bioavailable Fe (dissolved Fe (DFe) and total dissolved Fe (TDFe)), major ions (Na+, K+, Mg2+, Ca2+, Cl-,NO3-,SO42- and methanesulfonic acid (MSA)), heavy metal elements (Sr, Pb, V, Ti and Cd), and rare earth elements (REEs; specifically, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) and the oxygen and hydrogen isotopic compositions (δ18O and δD) from a series of surface snow samples collected during from January 22 to February 5, 2017 along a traverse from Zhongshan Station to Dome A in East Antarctica. The results reflect the Antarctic surface snow Fe and the other trace element concentrations on the East Antarctica ice sheet. In particular, the DFe and TDFe concentrations were measured using inductively coupled plasma sector field mass spectrometry (SF-ICP-MS). The concentration patterns of DFe and TDFe show three different stages along this transect. First, there is an abrupt decrease with distance inland from the coast and then a slight decreasing trend with increasing elevation. The maximum concentrations were observed at distances of 450-600 km from the coast, indicating that there are different potential sources and/or transporting air masses. The variations show that the sources and processes that deliver bioavailable Fe differ along this transect. These data are useful for assessing bioavailable Fe release from the Antarctic ice sheet.

The perchlorate record during 1956-2004 from Tienshan ice core, East Asia.

Perchlorate concentration in a shallow ice core at Tienshan, East Asia ranged between 0.55 and 52.1 ng L-1, with significant temporal variations during 1956-2004. Since the 1980s, a clear increasing trend of perchlorate was observed in the Miaoergou ice core, possibly the result of elevated stratospheric chlorine levels caused by emissions of anthropogenic volatile chlorine compounds. Although differences in trends and amounts were observed, the 1956-2004 perchlorate data from this study compares well with the perchlorate data from the High Arctic ice cores. The spatial and temporal differences of the perchlorate in Miaoergou ice core may be due to differences in anthropogenic sources. Such as, the nitrate ore field in Turpan-Hami Basin in eastern Xinjiang, China, may be the primary anthropogenic source. From the organic chlorine species emission data, HCFC-141b, HCFC-142b and HCFC-124 were identified as the primary anthropogenic sources responsible for the two perchlorate spikes observed for 1980-1996 and 1997-2001. The Miaoergou ice core covering the 1956-2004 period provides further evidence for the perchlorate deposition variations between mid-latitudes and the High Arctic regions.

Evaluation of Reference Genes for Quantitative PCR in Four Tissues from Rabbits with Hypercholesterolaemia

Abstract Rabbit with hypercholesterolaemia is an important model for studying cholesterol metabolism disease. This study aimed to evaluate the expression stability of nine reference genes for quantitative PCR (qPCR) analysis in adrenal gland, liver, spleen, and kidney tissue from rabbits with hypercholesterolaemia. In total, 30 male Harbin Large White (HLW) rabbits were fed a normal feed (n = 15) or a high cholesterol feed (n = 15) for 8 weeks to induce hypercholesterolaemia. Nine reference genes were verified by qPCR using cDNA extracted from rabbit tissue samples. For qPCR analysis, reference genes were evaluated using the RefFinder and GeNorm algorithms. Overall, seven rabbits with hypercholesterolaemia were identified based on body weight and total cholesterol measurements. Combining the results of the RefFinder and GeNorm algorithms, the most stable reference genes were hypoxanthine phosphoribosyltransferase 1 (Hprt1) and eukaryotic translation elongation factor 1 alpha 1 (Eef1a1) in the adrenal gland, β-2-microglobulin (B2m) and glyceraldehyde-3-phosphate dehydrogenase (Gapdh) in the liver, tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein zeta (Ywhaz) and Gapdh in the spleen, and peptidylprolyl isomerase (Ppia), β-actin (Actb), succinate dehydrogenase complex subunit A flavoprotein (Sdha), and B2m in the kidney. Taken together, our results confirmed that Hprt1 and Eef1a1, B2m and Gapdh, Ywhaz and Gapdh, and Ppia, Actb, Sdha, and B2m were the best reference genes for qPCR analyses in adrenal gland, liver, spleen, and kidney tissue, respectively, of rabbits with hypercholesterolaemia.