长江经济带林地和其他生物质碳储量及碳汇量研究

以全国林业应对气候变化碳汇计量监测体系建设结果数据为基础，应用森林碳库专项调查建立的碳计量模型和参数，结合历次森林资源清查成果等数据，估算了2020年长江经济带林地和其他生物质碳储量和碳汇量。研究表明：（1）2020年长江经济带林地碳储量24543.58 Tg C （其中森林植被碳储量为4372.85Tg C），散生木和四旁树等其他生物质碳储量329.59 Tg C。2020年长江经济带林地碳汇量81.81 Tg C/a （300.26Tg CO₂/a）、散生木和四旁树等其他生物质碳汇量6.60 Tg C/a （24.21 Tg CO₂/a）。无论是林地和其他生物质碳储量、碳汇量、还是森林植被碳储量，乔木林地所占比例最大（69%-85%）；长江经济带11个省市中，云南省最大，上海市最小；林地碳储量中土壤有机质碳库贡献最大（81.46%），林地碳汇量中生物量碳库贡献最大（90.99%）；林地碳汇量中"一直为林地的土地"产生碳汇量贡献最大（71.74%），其中一直为乔木林的土地产生的碳汇量占69.89%；（2）阐述了长江防护林工程、天然林资源保护工程、珠江防护林工程和沿海防护林工程4大重点生态工程对长江经济带碳储量和碳汇量的贡献，长江防护林工程贡献率最大（81%-83%），其次是天然林资源保护工程（32%-38%），珠江防护林工程和沿海防护林工程影响较小。分析了人工造林、中幼林抚育、次生林和低效林改造、退化林修复等生态保护修复措施对长江经济带碳储量和碳汇量的贡献，并提出了碳中和愿景下森林固碳增汇的有效途径。     

Microenvironment-induced TIMP2 loss by cancer-secreted exosomal miR-4443 promotes liver metastasis of breast cancer

We aimed to investigate the role of exosomal miR-4443 in metastasis of breast cancer (BCa). In vitro wound-healing assay and transwell invasion assay were used to investigate effect of miR-4443 on BCa cells. Animal experiments were performed to confirm its effects in vivo. miR-4443 promotes the metastasis of BCa cells through downregulating tissue inhibitors of metalloproteinase 2 (TIMP2) and upregulating matrix metalloproteinases (MMPs). Highly invasive BCa cells have a higher expression of miR-4443 in both cells and exosomes. The exosomes derived from highly invasive BCa cells mainly gather in the primary tumor and liver. In vivo, overexpression of miR-4443 in noninvasive BCa cells induces liver metastasis, accompanied with downregulated TIMP2, and upregulated MMP-2 in both the primary tumor and liver. When we armed MCF-10A exosomes with miR-4443 inhibitors to treat mice bearing high-miR-4443 tumors, exosomes accumulated in the primary tumor, and liver following the upregulation of TIMP2 and downregulation of MMP2, and the metastasis was inhibited. Highly invasive BCa cells destroy natural barriers against metastasis by delivering exosomal miR-4443 to stromal cells of the primary tumor and impairing TIMP2, consequently activating MMP; circulating exosomal miR-4443 might promote BCa cells lodging in future metastatic sites through the similar mechanisms.     

Novel SNPs in the <Emphasis Type="Italic">ATP1B2</Emphasis> gene and their associations with milk yield,milk composition and heat-resistance traits in Chinese Holstein cows

Genetic association analysis was applied to examine the effect of the Na⁺/K⁺-ATPase beta 2 subunit (ATP1B2) gene on rectal temperature, milk traits, K⁺ levels and Na⁺/K⁺-ATPase (NKA) activity in the red blood cells of 1001 Chinese Holstein cows under normal and heat-stress conditions. We detected two novel single nucleotide polymorphisms, G2258A and C2833T, in the second and fourth introns, respectively, of ATP1B2. G2258A significantly affected milk fat content (P < 0.05) and 305-day milk yield (P < 0.01), but not milk protein content. C2833T significantly affected milk protein content (P < 0.01) and 305-day milk yield (P < 0.05), but not milk fat content. Calculated gene substitution effects suggested that A to G substitution in G2258A, and T to C substitution in C2833T, positively affected milk fat content, 305-day milk yield and somatic cell score, but negatively affected milk protein content. We also detected significant variation in milk fat content, milk protein content, 305-day milk yield and somatic cell scores (P < 0.05 or P < 0.01) among the nine ATP1B2 haplotypes. Under heat-stress, the C2833T polymorphism was significantly related to rectal temperature (P < 0.01), red blood cell K⁺ levels, NKA activity and milk yield (P < 0.05). Cows with the TT genotype showed the desirable characteristics of low rectal temperature and red blood cell K⁺, low decline rate in milk yield and red blood cell NKA activity. This study suggests that the ATP1B2 single nucleotide polymorphism C2833T is a genetic marker of heat-resistance traits in Chinese Holstein cows.     

拟南芥授粉前后花粉与乳突细胞的超微结构

利用透射电子显微镜技术,对自交亲和植物拟南芥授粉前后花粉和乳突细胞的超微结构进行了观察。发现花粉和柱头乳突细胞一些未经报道的超微结构特征,可能与拟南芥花粉和乳突细胞的识别及花粉管生长相关:(1)成熟花粉中,电子透明的、体积较大的小液泡(直径200～1000nm)呈均匀分布。部分小液泡内含有多层膜状结构物质,推测可能是膜的一种储存形式,与花粉萌发时大量出现的小囊泡有关。(2)花粉萌发时,小液泡由均匀分布变为不均匀分布。(3)授粉前后的乳突细胞顶端和侧端的内壁上有明显的壁内突结构,粘附的花粉开始萌发时的乳突细胞壁内突处可观察到直径50～100nm的小泡存在,表明拟南芥乳突细胞具有一定的分泌功能。     

Cardiac telocytes exist in the adult Xenopus tropicalis heart

Recent research has revealed that cardiac telocytes (CTs) play an important role in cardiac physiopathology and the regeneration of injured myocardium. Recently, we reported that the adult Xenopus tropicalis heart can regenerate perfectly in a nearly scar‐free manner after injury via apical resection. However, whether telocytes exist in the X tropicalis heart and are affected in the regeneration of injured X tropicalis myocardium is still unknown. The present ultrastructural and immunofluorescent double staining results clearly showed that CTs exist in the X tropicalis myocardium. CTs in the X tropicalis myocardium were mainly twined around the surface of cardiomyocyte trabeculae and linked via nanocontacts between the ends of the telopodes, forming a three‐dimensional network. CTs might play a role in the regeneration of injured myocardium.     

Snail基因及其蛋白、E-cadherin蛋白在胃癌中的表达及其临床意义

目的观察Snail mRNA及其蛋白、E-cadherin蛋白在胃癌组织中的表达及其与胃癌临床病理特征的关系,并探讨它们在胃癌发生、发展中的作用及其临床应用价值。方法收集96例手术切除胃癌标本,同时取80例癌旁组织作为对照。应用免疫组织化学S-P法检测胃癌组织、癌旁组织中snail蛋白、E-cadherin蛋白的表达;运用原位分子杂交技术检测胃癌组织、癌旁组织中Snail mRNA的表达。结果（1）Snail蛋白在胃癌组织阳性率（83.3%）显著高于癌旁组织（41.25%）（P〈0.05）;高、中分化组Snail蛋白阳性表达率显著低于低分化组（P〈0.05）;Snail蛋白的阳性表达率在乳头状腺癌、管状腺癌及低分化腺癌与黏液癌之间差异有显著性（P〈0.05）;Snail蛋白的表达与胃癌浸润深度、淋巴结转移及远处转移有关（P〈0.05）,与性别、年龄、肿瘤大小、肿瘤部位及临床分期无关（P〉0.05）;（2）胃癌组织中snail mR-NA的阳性率（76%）显著高于癌旁组织（30%）（P〈0.05）;高、中分化组Snail mRNA阳性表达率显著低于低分化组（P〈0.05）;Snail mRNA的阳性表达率在乳头状腺癌、管状腺癌及低分化腺癌与黏液癌之间差异有显著性（P〈0.05）;Snail mRNA的表达与浸润深度及淋巴结转移有关（P〈0.05）,与性别、年龄、肿瘤大小、肿瘤部位、临床分期及远处转移无关（P〉0.05）;（3）E-cadherin蛋白在胃癌组织阳性率（37.5%）显著低于癌旁组织（100%）（P〈0.05）;高、中分化组E-cadherin蛋白阳性率显著高于低分化组（P〈0.05）;E-cadherin蛋白阳性率在乳头状腺癌、管状腺癌及低分化腺癌与黏液癌之间差异有显著性（P〈0.05）;E-cadherin蛋白的表达与胃癌浸润深度、淋巴结转移、临床分期及远处转移有关（P〈0.05）,与性别、年龄、肿瘤大小、肿瘤部位均无关（P〉0.05）;（4）胃癌组织中snail mRNA和snail蛋白的表达呈正相关（r=0.594,P〈0.05）;Snail蛋白和E-cadherin蛋白的表达呈负相关（r=-0.234,P〈0.05）。结论（1）E-cadher-in蛋白低表达与Snail蛋白高表达可能是胃黏膜恶性转变以及胃癌发生浸润转移的重要生物学标志;联合检测E-cadherin蛋白与Snail蛋白对预测胃癌浸润转移有重要意义。（2）Snail蛋白可能在转录水平上调控E-cadherin蛋白的表达。     

Novel aminopeptidase N inhibitors derived from antineoplaston AS2–5 (Part I)

Overexpression of zinc-dependent metalloproteinase, aminopeptidase N (APN/CD13), is considered to be involved in the process of tumor invasion and metastasis. Herein we describe the synthesis and in vitro enzymatic inhibition assay of antineoplaston AS2–5 scaffold peptidomimetic compounds. The results demonstrated that most of these l-iso-glutamine derivatives displayed selective inhibitory activity against APN as compared with MMP-2, with IC₅₀ values in the micromole range. The structure–activity relationships were also briefly discussed.