Effect of prostaglandin F2alpha on ovarian, adrenal, and pituitary hormones and on luteal blood flow in mares

The effect of a single injection of prostaglandin F2alpha (PGF) during mid-diestrus on systemic concentrations of progesterone, LH, FSH, estradiol, and cortisol and on blood flow to the corpus luteum was studied in 10 controls and 10 PGF-treated mares. Blood flow was assessed by estimating the percentage of corpus luteum with color-Doppler signals of blood flow during real-time scanning of the entire structure and by the diameter of the vascular pedicle near its attachment to the ovary. Treatment was done 8 days after ovulation and 0 h was immediately before the treatment. Examinations and collection of blood samples were done at 0 h, every 5 min until 1h, and then at 1.5, 2, 4, 8, 12, 24, 48, and 72 h. The concentrations of estradiol did not change, but progesterone, LH, FSH, and cortisol increased significantly within 5 min. Concentrations of LH and FSH in the PGF group remained elevated until a temporarily lower concentration at 8 or 4h, respectively, rebounded to 12h, and then slowly decreased. Cortisol remained elevated, until a decrease between 1 and 4h. Progesterone in the PGF group increased significantly until 10 min after 0 h and then decreased by 40 min to below the concentrations in controls. Within the PGF group, progesterone decreased significantly by 45 min to below the concentrations at 0 h. The values for each of the two indicators of blood flow did not differ significantly between the PGF and control groups until a decrease at 24h in the PGF group. Results did not support the hypothesis that the immediate transient post-PGF increase in progesterone was associated with an increase in luteal blood flow. Luteolysis, as indicated by decreasing progesterone, began well before the beginning of a decrease in luteal blood flow.     

Transthoracic echocardiographic measurement of patent ductus arteriosus in dogs

BACKGROUND: Patent ductus arteriosus (PDA) size and morphology influence the selection of the kind and the size of the embolization device used to effect shunt closure. HYPOTHESIS: That echocardiographic measurement of PDA in dogs is accurate. ANIMALS: Forty-five client-owned dogs with PDA. METHODS: Prospective observational study. Echocardiographic and angiographic data were compared. RESULTS: Measurement of the ductus in color Doppler echocardiography (CD-E) and 2-dimensional echocardiography (2D-E) was achieved from left parasternal views in 43 of 45 unsedated dogs (96%). In these 43 dogs, the angiographic minimal PDA diameter was 3.72 +/- 1.59 mm, and the diameter of the PDA ampulla was 8.46 +/- 3.01 mm. The CD-E minimal PDA diameter ranged from 2.3 to 9.5 mm (median, 4.0 mm). There was a significant mean difference to the angiographic measurements (1.15 +/- 0.95 mm; P < .0001). An agreement in a 1-mm range was found in 21 of 43 dogs (48%). The 2D-E minimal PDA diameter was 3.73 +/- 1.78 mm, and the mean difference to the angiographic measurements was not significant (0.00 +/- 0.72 mm; P = .98). An agreement in a 1-mm range was found in 31 of 43 dogs (72%). The 2D-E measurement of the PDA ampulla revealed a significant mean difference to the angiographic data (1.95 +/- 2.43 mm, P < .0001). An agreement in a 2-mm range was found in 21 of 43 dogs (49%). CONCLUSIONS AND CLINICAL IMPORTANCE: The 2D-E from the left cranial parasternal view is an excellent noninvasive method to estimate the PDA minimal diameter before doing catheter intervention.     

CoCl2对Na2CO3胁迫下苜蓿幼苗叶片细胞膜的保护作用

本研究报道了CoCl2对Na2CO3胁迫下苜蓿幼苗叶片细胞膜的保护作用及机制,研究结果表明,在120mmol/L Na2CO3胁迫的前期,苜蓿幼苗叶片多胺含量及抗氧化酶活性显著升高,过氧化物酶除外,而活性氧水平、脂质过氧化程度和细胞膜相对透性无显著变化;当120 mmol/L Na2CO3胁迫延长至24~28 d时,乙烯产生速率大幅度上升,多胺氧化酶及二胺氧化酶活性显著升高,精胺、亚精胺和腐胺含量显著下降;抗氧化酶活性显著下降,活性氧水平与脂质过氧化程度显著提高,细胞膜稳定指数大幅度下降。在120 mmol/L Na2CO3溶液中加入CoCl2至50μmol/L,在胁迫的整个过程中乙烯产生被显著抑制,同时相对提高了抗氧化酶的活性,并在胁迫后期显著减轻了多胺氧化酶活性升高、多胺含量下降及脂质过氧化程度的增加,减缓了细胞膜稳定指数的下降,从而对Na2CO3胁迫下苜蓿幼苗叶片细胞膜表现出一定的保护作用。     

CO2浓度增加对半干旱区马铃薯生长动态及产量、品质的影响

为了解CO₂浓度升高条件下马铃薯生长动态及其产量、品质的变化特征,在典型半干旱区（甘肃定西）利用开顶式气室(OTC)试验平台,以马铃薯‘新大坪’为供试品种,设对照(390 μmol·mol^-1)和590 μmol·mol^-1共2个CO₂浓度梯度,开展CO₂浓度增加模拟试验。结果表明：CO₂浓度增加至590 μmol·mol^-1时,马铃薯发育加快,生育期提前,全生育期天数缩短3 d;CO₂浓度升高对马铃薯株高、叶面积指数、叶绿素含量和叶片水势有明显促进作用。随着生育进程的推移,马铃薯地上部干物质生产对CO₂浓度的响应值呈现先变大再变小的趋势。CO₂浓度增加促进了马铃薯块茎产量的提高,单株结薯数和单株薯块质量也有所增加。与对照相比,590 μmol·mol^-1CO₂处理马铃薯块茎水分、蛋白质、维生素C含量以及铁、锌、铜元素含量分别下降3.43%、11.78%、13.09%、25.58%、31.94%和9.76%,而粗淀粉、粗脂肪、粗纤维和还原糖含量分别增加10.56%、240.00%、14.28%、106.38%。     

国内外致泻大肠埃希氏菌O157:H7的检测标准比较及建议

致泻大肠埃希氏菌O157:H7（STEC O157:H7）是大肠埃希氏菌中致病性最严重的一种食源性致病菌,主要存在于牛肉、牛奶、水果及其制品中,对身体健康造成很大危害,甚至引发死亡。食品中STEC O157:H7检测尤为重要。本文对国内外STEC O157:H7的检测标准进行比较,提出我国标准在样品前处理、快速筛选方法的应用等方面需要加强,以便为该菌快速准确检测提供帮助,实现与国际标准化体系建设接轨,满足实验室检测需要。     

中国草地固碳减排研究现状及其建议

随着经济的快速发展,温室气体的排放量不断增加,加之人类对自然资源的利用强度逐渐增加,导致全球生态系统的固碳能力减弱,大气中的温室气体浓度达到新高,所造成的温室效应已经成为国际社会普遍关注的重大全球性问题。中国草地碳汇资源得天独厚,发展草原碳汇经济成为履行国际承诺、打造碳汇新经济、建设美丽中国的重要载体。综述中国草地固碳减排现状及其影响因素,包括草地碳汇和家畜生产减排研究、气候变化背景下的草地碳汇、人工草地建设等方面,并提出中国草地固碳减排发展建议,以期为中国实现碳达峰、碳中和及草地固碳减排的贡献提供理论基础,为推动我国社会高质量发展、创造高品质生活提供坚实的技术支撑。     

PA-X基因的长度变化对H3N2犬流感病毒复制能力和致病性的影响

H3N2犬流感病毒(canine influenza virus, CIV)已在中国多地的犬群中流行,是禽流感跨宿主感染并形成新分支的近期案例。研究表明,PA-X基因与甲型流感病毒适应新宿主的能力相关,且其长度能够影响甲型流感病毒的复制及致病能力。为了解PA-X基因的长度变化对H3N2 CIV复制能力及致病力的影响,本研究利用H3N2 CIV的8质粒操作系统,拯救了三株重组H3N2 CIV毒株：PA-X基因表达大小为232个氨基酸多肽的亲本病毒CIV＿PA-X＿232;对PA编码区第191、192位氨基酸的密码子进行改造,PA-X基因不表达蛋白的重组病毒CIV＿PA-X＿Knock;对PA+1编码区第232位氨基酸进行突变,PA-X基因表达大小为252个氨基酸多肽的重组病毒CIV＿PA-X＿252。通过比较3株重组病毒的聚合酶活性,在MDCK细胞中的复制效率及对小鼠致病性的差异,来评价表达不同长度的PA-X基因对H3N2 CIV的影响。结果显示,CIV＿PA-X＿252和CIV＿PA-X＿Knock的聚合酶活性显著(P<0.05)高于CIV＿PA-X＿232,且CIV＿PA-X＿...