Spatial and temporal expression of c-Kit in the development of the murine submandibular gland

The c-Kit pathway is important in the development of many mammalian cells and organs and is indispensable for the development of hematopoiesis, melanocytes, and primordial germ cells. Loss-of-function mutations in c-Kit lead to perinatal death in mouse embryos. Previously, c-Kit has been used as one of salivary epithelial stem or progenitor cell markers in mouse, its specific temporo-spatial expression pattern and function in developing murine submandibular gland (SMG) is still unclear. Here we used quantitative real-time PCR, in situ hybridization, and immunohistochemistry analysis to detect c-Kit expression during the development of the murine SMG. We found that c-Kit was expressed in the epithelia of developing SMGs from embryonic day 11.5 (E11.5; initial bud stage) to postnatal day 90 (P90; when the SMG is completely mature). c-Kit expression in the end bud epithelium increased during prenatal development and then gradually decreased after birth until its expression was undetectable in mature acini at P30. Moreover, c-Kit was expressed in the SMG primordial cord at the initial bud, pseudoglandular, canacular, and terminal end bud stages. c-Kit was also expressed in the presumptive ductal cells adjacent to the developing acini. By the late terminal end bud stage on P14, c-Kit expression could not be detected in ductal cells. However, c-Kit expression was detected in ductal cells at P30, and its expression had increased dramatically at P90. Taken together, these findings describe the spatial and temporal expression pattern of c-Kit in the developing murine SMG and suggest that c-Kit may play roles in epithelial histo-morphogenesis and in ductal progenitor cell homeostasis in the SMG.     

Profiling of RNA ribose methylation in Arabidopsis thaliana

Eukaryotic rRNAs and snRNAs are decorated with abundant 2′-O-methylated nucleotides (Nm) that are predominantly synthesized by box C/D snoRNA-guided enzymes. In the model plant Arabidopsis thaliana, C/D snoRNAs have been well categorized, but there is a lack of systematic mapping of Nm. Here, we applied RiboMeth-seq to profile Nm in cytoplasmic, chloroplast and mitochondrial rRNAs and snRNAs. We identified 111 Nm in cytoplasmic rRNAs and 19 Nm in snRNAs and assigned guide for majority of the detected sites using an updated snoRNA list. At least four sites are directed by guides with multiple specificities as shown in yeast. We found that C/D snoRNAs frequently form extra pairs with nearby sequences of methylation sites, potentially facilitating the substrate binding. Chloroplast and mitochondrial rRNAs contain five almost identical methylation sites, including two novel sites mediating ribosomal subunit joining. Deletion of FIB1 or FIB2 gene reduced the accumulation of C/D snoRNA and rRNA methylation with FIB1 playing a bigger role in methylation. Our data reveal the comprehensive 2′-O-methylation maps for Arabidopsis rRNAs and snRNAs and would facilitate study of their function and biosynthesis.     

Alien woody plant invasions in natural forests across China

外来木本植物在我国天然林中的入侵 外来植物入侵已经成为一个主要的全球性环境问题，造成了严重的经济和生态破坏。中国区域内部分地区已有关于严重入侵情况的报道，但是大多是小尺度上的研究，全国范围天然林中的外来植物入侵情况仍不清楚。本文基于全国天然林的3573个样方数据，绘制了外来木本植物入侵在我国各地天然林中的空间分布格局，探究了可能的环境和社会经济控制因素。研究结果显示，只有271个样方被外来木本植物入侵，占样方总数的7.58%；在所有调查的2825种木本植物中，只有5个外来物种(占比0.177%)。人类活动和气候因素都对入侵格局产生影响。由于我国天然林多位于偏远山区，人为干扰较轻，外来木本植物入侵的报道少于北美森林和欧洲林地。然而，随着交通运输的发展和山区经济活动的增加，在不久的将来可能会有更多。因此，需要积极的管理和政策制定来防止或减缓入侵进程，降低人类活动的干扰，监测外来物种的入侵情况并及时做出应对。     

The measurement of ocular axial length in normal human eyes based on an improved Twyman-Green interferometer

In order to meet the demands of myopia prevention, as well as the increasing needs of measurement for refractive and cataract operations in China, a new axial length (AL) measurement system combining an improved Twyman-Green interferometer with digital signal processing has been established. The ALs of 33 eyes of different optical refractive subjects (−8.50 ~ 0.50 D) were measured with the New AL and intraocular lens (IOL) master. The repeatability of measurements with the New AL was assessed using coefficient of variation (CoV) and intra-group correlation coefficient (ICC). Comparison, correlation, linear regression and agreement of AL between devices were analyzed. There was good repeatability (CoV = 0.0617%, ICC = 0.9999) with the New AL and great agreement has been obtained with both devices. These show that the New AL is capable of providing precise AL values over the normal AL range compared to the IOL master, and indicate that the New AL developed can be used for routine clinical AL measurements.     

Inorganic nitrate alleviates the senescence-related decline in liver function

Senescence-related decline in liver function is a common complication in the elderly that can lead to impaired health in older individuals.Dietary nitrate supplements have physiological and therapeutic effects on organ function by nitrate(NO_3~-)-nitrite(NO_2~-)-nitric oxide(NO)pathway.However,the role of dietary nitrate on the senescence-related decline in liver function is unclear.The findings of the present study showed that nitrate levels in the serum and liver decreased,whereas the levels of alanine aminotransferase(ALT)and aspartate aminotransferase(AST)in serum increased in ageing mice.Consistently,cell senescence,decreased glycogen levels and increased lipid deposition were found in the liver of aged mice,both glucokinase(GCK)and phosphoenolpyruvate carboxykinase(PCK)were down-regulated(n=10).Daily nitrate intake(0.5 mmol L~(-1))restored nitrate levels,decreased ALT and AST levels,and prevented cell senescence and structural and glucose and lipid metabolism degeneration in liver tissue both in D-galactose(D-gal)-induced ageing mice(n=10)and in natural aged mice(n=10).In conclusion,the present study demonstrated that the reduction of nitrate levels was correlated with liver degeneration in ageing individuals and that dietary supplement of nitrate could restore the nitrate levels in serum and the liver and prevent ageing-related liver degeneration.     

Variable effects of forest diversity on invasions by non-native insects and pathogens

Biodiversity and Conservation - The geographical distributions of non-native forest insects and pathogens (pests) result from a multitude of interacting abiotic and biotic factors. Following...     

A genome-wide survey of NOD-like receptors in Chinese tongue sole (Cynoglossus semilaevis): Identification,characterization and expression analysis in response to bacterial infection

As intracellular pathogen recognition receptors (PRRs), nucleotide-binding domain, leucine-rich repeat containing receptors (NLRs, NOD-like receptors) are involved in innate immune responses in vertebrates. However, there is no systemic study on NLRs in Chinese tongue sole (Cynoglossus semilaevis), a popular maricultured fish in China. In the present study, a genome-wide survey of NLRs was performed in C. semilaevis, with the identification of 29 NLRs, including five genes from the NLR-A subfamily (referred to as CsNOD1-5), two genes from the NLR-B subfamily, 18 genes from the NLR-C subfamily (referred to as CsNLR-C1 to 18) and four other NLR genes. Phylogenetic analysis implied that CsNOD1-5 contained conserved functional domains and had orthologous relationships with human NOD1-5. Moreover, CsNLR-C genes all possessed the FISHNA domain, which is a fish-specific NACHT subdomain. Expression analysis showed that CsNOD1-5 and CsNLR-C1/2 were ubiquitously expressed in various normal tissues. Bacterial infection with Vibro harveyi revealed distinct expression patterns of all the tested CsNLRs in gill, intestine, trunk kidney, liver and spleen. In particular, CsNOD1-4 and CsNLR-C2 were significantly upregulated in gills at 48 h post bacterial infection. In addition, CsNOD3 and CsNOD4 were significantly elevated in infectious intestine, trunk kidney, liver and spleen, revealing that their expressions were more sensitive to bacterial infection than other CsNLRs. Together with the computational protein–protein interaction network of CsNLRs, it was suggested that individual NLR genes had different roles in the innate immune cascades of C. semilaevi against bacterial infection. This study provides valuable information for further studies on CsNLR immune function.