籼稻的抗冷性与亲本的关系

四个籼稻（Ｏｒｙｚａ ｓａｔｉｖａ Ｌ．）品种幼苗经１℃黑暗或光照２５０ μｍ ｏｌ·ｍ － ２·ｓ－ １处理后,抗冷的“桂山矮选３”比不抗冷的“青华６ 号”幼苗存活率高,其子代是以“桂山矮选３”为母本的比“青华６ 号”为母本的存活率较高。抽穗期剑叶经光照低温处理１２、２４ 和３６ ｈ 后,光合作用是“桂山矮选３”和以“桂山矮选３”为母本的子代比“青华６ 号”和以“青华６ 号”为母本的子代下降较少。呼吸作用是前者比后者在处理１２ ｈ 时有明显升高现象。荧光参数Ｆｖ／Ｆｏ和Ｆｖ／Ｆｍ比值在处理２４ ｈ 时前者比后者下降明显,但在常温下恢复则是前者比后者明显较快。自然低温（寒露风）对叶绿素荧光的影响亦有相似的规律。对水稻后代的抗冷性倾向于母本进行了讨论     

贵州沿河土地坳下奥陶统牙形石

本文报道了采自贵州沿河土地坳下奥陶统的牙形石,计有２５属３９种,根据牙形石组合特片分析,认为其与黔北其它地区下奥陶统牙形石组合面貌基本一致,属北大西洋牙形石动物地理区。     

Human Organoids as a Promising Platform for Fighting COVID-19

The coronavirus disease 2019 (COVID-19) global pandemic evoked by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has triggered a major public health problem with significant morbidity and mortality. Understanding the pathogenesis and molecular mechanisms underlying this novel virus is crucial for both fundamental research and clinical trials in order to devise effective therapies and vaccination regimens. Basic research on SARS-CoV-2 largely depends on ex vivo models that allow viral invasion and replication. Organoid models are now emerging as a valuable tool to investigate viral biology and disease progression, serving as an efficient platform to investigate potential therapies for COVID-19. Here, we summarize various human stem cell-derived organoid types employed in SARS-CoV-2 studies. We highlight key findings from these models, including cell tropisms and molecular mechanisms in viral infection. We also describe their use in identifying potential therapeutic agents against SARS-CoV-2. As more and more advanced organoids emerge, they will facilitate the understanding of disease pathogenesis for drug development in this dreaded pandemic.     

Integrative taxonomy recognized a new cryptic species within Stipa grandis from Loess Plateau of China

Stipa shanxiensis, a cryptic species within Stipa grandis that originated from central and western China, is described based on morphological, genomic, and ecological data from field and common garden experiments. Stipa shanxiensis morphologically resembles S. grandis, although phylogenetically it is closely related to the less morphologically similar Stipa baicalensis and Stipa krylovii. Of the eight significant morphological differences between S. shanxiensis and S. grandis, the two, cauline ligules longer than 2 cm with a filiform apex, and hairs shorter than 0.2 mm on the adaxial surface of the cauline uppermost leaves can be used to distinguish the species. Results from a common garden experiment verified that the two diagnostic characteristics were relatively stable and less morphologically plastic in response to environmental variation. Furthermore, a significant ecological divergence was found between S. shanxiensis and S. grandis, such that the former preferred warmer and more humid climates, and their predicted distribution was generally separated. Taken together, our results highlight that the integrative taxonomic approach was valuable for recognizing a new cryptic species in Stipa. In particular, we find that common garden experiments involving the effects of growth stage and characteristic position helped to morphologically diagnose cryptic species. These findings may also facilitate our understandings of ecological adaption and phenotypic plasticity in response to environmental change.     

Development of a biosensor assessing SARS-CoV-2 main protease proteolytic activity in living cells for antiviral drugs screening

Highlights:
The biosensor reported in our study can monitor SARS-CoV-2 M^pro activity in living cells instead of in vitro solutions.
The biosensor reported in our study is sensitive and easy to operate.
It is suitable for high-throughput screening.
It has the potential to be used in small animal models.     

NCAM regulates the proliferation,apoptosis, autophagy,EMT, and migration of human melanoma cells via the Src/Akt/mTOR/cofilin signaling pathway

The neural cell adhesion molecule (NCAM) plays critical roles in multiple cellular processes in neural cells, mesenchymal stem cells, and various cancer cells. However, the effect and mechanism of NCAM in human melanoma cells are still unclear. In this study, we found that NCAM regulated the proliferation, apoptosis, autophagy, migration, and epithelial-to-mesenchymal transition of human melanoma cells by determining the biological behavior of NCAM knockdown A375 and M102 human melanoma cells. Further studies revealed that NCAM knockdown impaired the organization of actin cytoskeleton and reduced the phosphorylation of cofilin, an actin-cleaving protein. When cells were transfected with cofilin S3A (dephosphorylated cofilin), biological behavior similar to that of NCAM knockdown cells was observed. Research on the underlying molecular mechanism showed that NCAM knockdown suppressed activation of the Src/Akt/mTOR pathway. Specific inhibitors of Src and PI3K/Akt were employed to further verify the relationship between Src/Akt/mTOR signaling and cofilin, and the results showed that the phosphorylation level of cofilin decreased following inhibition of the Src/Akt/mTOR pathway. These results indicated that NCAM may regulate the proliferation, apoptosis, autophagy, migration, and epithelial-to-mesenchymal transition of human melanoma cells via the Src/Akt/mTOR/cofilin pathway-mediated dynamics of actin cytoskeleton.     

Monophosphoryl lipid A alleviated radiation-induced testicular injury through TLR4-dependent exosomes

Radiation protection on male testis is an important task for ionizing radiation-related workers or people who receive radiotherapy for tumours near the testicle. In recent years, Toll-like receptors (TLRs), especially TLR4, have been widely studied as a radiation protection target. In this study, we detected that a low-toxicity TLR4 agonist monophosphoryl lipid A (MPLA) produced obvious radiation protection effects on mice testis. We found that MPLA effectively alleviated testis structure damage and cell apoptosis induced by ionizing radiation (IR). However, as the expression abundance differs a lot in distinct cells and tissues, MPLA seemed not to directly activate TLR4 singling pathway in mice testis. Here, we demonstrated a brand new mechanism for MPLA producing radiation protection effects on testis. We observed a significant activation of TLR4 pathway in macrophages after MPLA stimulation and identified significant changes in macrophage-derived exosomes protein expression. We proved that after MPLA treatment, macrophage-derived exosomes played an important role in testis radiation protection, and specially, G-CSF and MIP-2 in exosomes are the core molecules in this protection effect.     

A new Illumina MiSeq high-throughput sequencing-based method for evaluating the composition of the Bacteroides community in the intestine using the rpsD gene sequence

Bacteroides is a bacterial genus that is known to closely interact with the host. The potential role of this genus is associated with its ecological status and distribution in the intestine. However, the current 16S V3–V4 region sequencing method can only detect the abundance of this genus, revealing a need for a novel sequencing method that can elucidate the composition of Bacteroides in the human gut microbiota. In this study, a core gene, rpsD, was selected as a template for the design of a Bacteroides-specific primer set. We used this primer set to develop a novel assay based on the Illumina MiSeq sequencing platform that enabled an accurate assessment of the Bacteroides compositions in complex samples. Known amounts of genomic DNA from 10 Bacteroides species were mixed with a complex sample and used to evaluate the performance and detection limit of our assay. The results were highly consistent with those of direct sequencing with a low Bacteroides DNA detection threshold (0.01 ng), supporting the reliability of our assay. In addition, the assay could detect all the known Bacteroides species within the faecal sample. In summary, we provide a sensitive and specific approach to determining the Bacteroides species in complex samples.