新造林中的防火隔离带建设

新造林中防火隔离带分为天然防火隔离带;植物防火隔离带;防火林道,人工防火线等4种。在具体布设上则分为林中防火、林线防火、山脊防火、境界防火、铁路沿线、林区房屋隔离带6种。     

Cell-free extract from porcine induced pluripotent stem cells can affect porcine somatic cell nuclear reprogramming

Pretreatment of somatic cells with undifferentiated cell extracts, such as embryonic stem cells and mammalian oocytes, is an attractive alternative method for reprogramming control. The properties of induced pluripotent stem cells (iPSCs) are similar to those of embryonic stem cells; however, no studies have reported somatic cell nuclear reprogramming using iPSC extracts. Therefore, this study aimed to evaluate the effects of porcine iPSC extracts treatment on porcine ear fibroblasts and early development of porcine cloned embryos produced from porcine ear skin fibroblasts pretreated with the porcine iPSC extracts. The Chariot^TM reagent system was used to deliver the iPSC extracts into cultured porcine ear skin fibroblasts. The iPSC extracts-treated cells (iPSC-treated cells) were cultured for 3 days and used for analyzing histone modification and somatic cell nuclear transfer. Compared to the results for nontreated cells, the trimethylation status of histone H3 lysine residue 9 (H3K9) in the iPSC-treated cells significantly decreased. The expression of Jmjd2b, the H3K9 trimethylation-specific demethylase gene, significantly increased in the iPSC-treated cells; conversely, the expression of the proapoptotic genes, Bax and p53, significantly decreased. When the iPSC-treated cells were transferred into enucleated porcine oocytes, no differences were observed in blastocyst development and total cell number in blastocysts compared with the results for control cells. However, H3K9 trimethylation of pronuclear-stage-cloned embryos significantly decreased in the iPSC-treated cells. Additionally, Bax and p53 gene expression in the blastocysts was significantly lower in iPSC-treated cells than in control cells. To our knowledge, this study is the first to show that an extracts of porcine iPSCs can affect histone modification and gene expression in porcine ear skin fibroblasts and cloned embryos.     

Influence of dopamine on rumino-reticular motility and rumination in sheep

The effects of intracerebroventricular (i.c.v.) and intravenous (i.v.) administration of dopamine and its antagonists (domperidone and metoclopramide) on forestomach motility were investigated in four sheep fitted with Nichrome electrodes and strain gauges implanted on the reticulum and the caudo-dorsal sac of the rumen. Infused by the i.c.v. route at a rate of 2 micrograms . kg-1 . min-1, dopamine inhibited the phasic contractions of the reticulo-rumen. A similar effect was obtained following i.v. administration of doses which were 10 times higher, but the effect was associated with an increased tone of the rumen wall. Prior i.v. administration of domperidone (0.5 micrograms . kg-1) blocked these effects and a selective blockade of the dopamine-induced inhibition of phasic contractions was obtained with higher dose of domperidone (2.5 micrograms . kg-1) administered centrally. When dopamine was infused alone ventricularly or intravenously after metoclopramide (40 micrograms . kg-1), it induced a transient (6-8 min) period of rumination, which could be blocked by a prior i.c.v. administration of tolazoline. It was concluded that dopamine acts on rumino-reticular motility in sheep through specific dopamine receptors (i) centrally by inhibiting the frequency of reticular contraction and (ii) peripherally by increasing the muscular tone of the rumen, and its effects on rumination involved alpha 2 adrenergic receptors located in the central nervous system.     

Central and peripheral serotonergic control of forestomach motility in sheep

Participation of tryptaminergic receptors in the control of forestomach motility was investigated in conscious sheep using strain-gauges and chronically implanted electrodes. Two hours after feeding the sheep, serotonin (5-HT) was infused into the jugular vein (i.v.), or the carotid artery (i.c.), or into the lateral cerebral ventricles (i.c.v.), over a 10-min period. An i.v. dose of 16 micrograms/kg/min abolished the cyclic propagated contractions throughout the forestomach, increased ruminoreticular tone, and induced simultaneous contractions of all the parts of the rumen. A dose of 1.6 micrograms/kg/min i.c. or i.v. 5-HT inhibited phasic contractions. The effects of 5-HT were blocked completely by i.c.v. administration of methysergide (20 micrograms/kg) and imipramine (200 micrograms/kg), and blocked partially by naloxone (25 micrograms/kg), but unaffected by atropine (50 micrograms/kg). The inhibitory effects of i.v. 5-HT were antagonized by methysergide (200 micrograms/kg, i.v.) but unaffected by imipramine (2 mg/kg, i.v.) and atropine (250 micrograms/kg, i.v.). Only the i.v. administration of methysergide blocked the inhibition induced by i.c. infusion (1.6 micrograms/kg/min) of 5-HT. It is suggested that 5-HT exhibits an inhibitory control on forestomach phasic contractions through hypothalamic and bulbar 5-HT receptors, and exerts peripheral excitatory effects on the tone of the rumen wall.     

《木材水运建筑安装工程预算定额》修订和《概、预算编制办法及费用定额》编制

1994年9月～1995年9月,由主编单位四周林业勘察设计研究院承担《木材水运建筑安装工程预算定额》的修订和《木材水运建筑安装工程概、预算编制办法及费用定额》的编制。定额的修定一方面要与相关定额水平协调,同时将工程实体消耗量和施工措施性消耗分开;贯彻政府有关文件精神并反映当前平均先进水平;保留(64)定额的框架只对章,节目和消耗量,基价作调整。 新编《木材水运建筑安装工程概、预算编制办法及费用定额》,以办法与费用定额合一,简化文字实用为原则,项目设置、费用定额符合政府部门最新规定。结合实际控制水平,按工程性质划分为7项生产性主体工程;5项附属性工程;2项非生产性工程和其它工程及费用两大部分。     

In vitro development of canine somatic cell nuclear transfer embryos in different culture media

The objective of the present study was to investigate the effects of three different culture media on the development of canine somatic cell nuclear transfer (SCNT) embryos. Canine cloned embryos were cultured in modified synthetic oviductal fluid (mSOF), porcine zygote medium-3 (PZM-3), or G1/G2 sequential media. Our results showed that the G1/G2 media yielded significantly higher morula and blastocyst development in canine SCNT embryos (26.1% and 7.8%, respectively) compared to PZM-3 (8.5% and 0%) or mSOF (2.3% and 0%) media. In conclusion, this study suggests that blastocysts can be produced more efficiently using G1/G2 media to culture canine SCNT embryos.