In mammals, sterol regulatory element binding protein-1 (SREBP-1) is the master regulator of fatty acid and triacylglycerol synthesis. Recent gene silencing studies in mammary cells indicate that SREBP-1 has a central role in milk fat synthesis. However, SREBP-1 knockdown studies in goat mammary cells have not been performed; hence, its direct role in controlling mRNA expression of lipid metabolism genes and triacylglycerol synthesis remains unknown. Inhibition of SREBP-1 in goat mammary epithelial cells (GMEC) by small interference RNA (siRNA) markedly reduced the content of cellular triacylglycerol (~50% decrease, P < 0.05) and was partly related to downregulation of AGPAT6, LPIN1, and DGAT2 (-23%, -28% and -19%, respectively. P < 0.05), which are key enzymes involved in triacylglycerol synthesis, cellular triacylglycerol content and lipid droplet accumulation all decreased by SREBP-1 inhibition. The expression of lipid droplet formation and secretion genes was not altered in response to treatment. Although the lack of effect on expression of ACACA and FASN (rate-limiting enzymes for de novo fatty acid synthesis) with SREBP-1 knockdown was unexpected (P > 0.05), the downregulation of genes related to synthesis of acetyl-CoA and acetate activation (ACLY, ACSS2, and IDH1, P < 0.05) suggests that lipogenesis was inhibited. SREBP-1 knockdown also resulted in decreased expression of genes associated with fatty acid desaturation and elongation (SCD1 and ELOVL6, P < 0.05), long-chain fatty acid (LCFA) activation and transport (ACSL1, FABP3, and SLC27A6, P < 0.05). The results underscored the essential role of SREBP-1 not only in fatty acid synthesis but also in desaturation, elongation, and esterification in GMEC. Clearly, the lack of effect on ACACA and FASN, both of which are considered the key lipogenic enzymes, implies that there may be different regulatory mechanisms in goat compared with bovine mammary cells.

Sterol regulatory element binding protein 1 (SREBP‐1) is well‐known as the master regulator of lipogenesis in rodents. Acyl‐CoA synthetase short‐chain family member 2 (ACSS2) plays a key role in lipogenesis by synthesizing acetyl‐CoA from acetate for lipogenesis. ATP citrate lyase (ACLY) catalyzes the conversion of citrate and coenzyme A to acetyl‐CoA, hence, it is also important for lipogenesis. Although ACSS2 function in cancer cells has been elucidated, its essentiality in ruminant mammary lipogenesis is unknown. Furthermore, ACSS2 gene promoter and its regulatory mechanisms have not known. Expression of ACSS2 was high in lipid synthesizing tissues, and its expression increased during lactation compared with non‐lactating period. Simultaneous knockdown of both ACSS2 and ACLY by siRNA in primary goat mammary epithelial cells decreased (p < 0.05) the mRNA abundance of genes associated with de novo fatty acid synthesis (FASN, ACACA, SCD1) and triacylglycerol (TAG) synthesis (DGAT1, DGAT2, GPAM, and AGPAT6). Genes responsible for lipid droplet formation and secretion (PLIN2 and PLIN3) and fatty acid oxidation (ATGL, HSL, ACOX, and CPT1A) all decreased (p < 0.05) after ACSS2 and ACLY knockdown. Total cellular TAG content and lipid droplet formation also decreased. Use of a luciferase reporter assay revealed a direct regulation of ACSS2 by SREBP‐1. Furthermore, SREBP‐1 interacted with an SRE (SREBP response element) spanning at −475 to −483 bp on the ACSS2 promoter. Taken together, our results revealed a novel pathway that SREBP‐1 may regulate fatty acid and TAG synthesis by regulating the expression of ACSS2.

Selecting 10-year-old peony variety Luoyanghong as experimental material,the dynamic changes of leaf nutrition and substrate available nutrient of the potted peony were studied,and the relationship between them in different periods was analyzed.The results indicated that the content of phosphorus and potassium in the leaves had decreased as a whole.The content of available phosphorus and available potassium in the substrate appeared the decreasing tendency at first,but it increased at certain special stage,and then it decreased again after blossom bud differentiation.There was significant negative correlation between the available phosphorus content in the substrate at flowering and blossom bud differentiation stages and the phosphorus content in the leaves at leaf fall stage.A significant positive correlation was found between the available potassium content in the substrate at flowering stage and the potassium content in the leaves at blossom bud differentiation stage.So it was better to apply phosphorus fertilizer before flowering and potassium fertilizer in flowering period.

Drought tolerance of six Dendranthema×grandiflorum cultivars(Jinbeidahong,Tianxiayipin,Quanxiangchongtian,Ziyu,Guohuahuangzhuan and Junhedewu) under drought stress was evaluated with subordinative function,and the physiological and biochemical indexes such as exosmosis rate of cytoplasm,content of malondialdehyde(MDA),activities of superoxide dismutase(SOD) and peroxidase(POD),and the relative chlorophyll contents were measured.Comparing with control,with the degree of drought stress increase,the protoplasmic membrane penetrability of diferent species increased continually,while the chlorophyll contents were decreased gradually.The protective enzyme's(SOD and POD)activity of six cultivars presented to rise first and then drop,and reached its maximum on 18 days in the condition of drought stress.The MDA content of Guohuahuangzhuan and Ziyu kept increasing,whereas other cultivars showed the trend of declining firstly and then rising.The comprehensive evaluation of the six cultivars was handled by using the subordinative function method.The drought tolerance of six chrysanthemum cultivars is in the following order:Jinbeidahong,Tianxiayipin,Quanxiangchongtian,Ziyu,Guohuahuangzhuan and Junhedewu.

Variations of superoxide dismutase(SOD)and catalase(CAT)activity,malondialdehyde(MDA) content,ultramimcroscopic structure of Machilus ichangensis seedlings at different temperatures were investigated. The data suggested that SOD and CAT activities were increased firstly and then decreased,and the number of mitochondria and starch grains increased with the temperature decline.When the temperature dropped to 5℃,SOD and CAT activities reached to the top,MDA content reached to the lowest point.As the temperature continued to decline,SOD and CAT activities both showed downward trend, MDA content began to increase gradually.When the temperature was—5℃,it was proved by transmission electron microsope observation that plasmalemma and chloroplast were damaged or destroyed.At the same time,the starch grains was degraded.

Taking 1～4 years trees of young secondary Robinia pseudoacacia L.bush forest as objects,dividing them into 4 groups by age,each group having 30 samples and constructing 120 units in all,this study observes the wood fiber's length,width,wall thickness,lumen diameter,ratio of length to width,ratio of wall to lumen.The results of variance analysis and multiple comparison show: the variation of the wood fibers among R.pseudoacacias at different ages is notable;The wood fiber of triennial R.pseudoacacia is the longest,widest and thickest;The wood fiber's ratio of wall to lumen of different tree ages' R.pseudoacacia is less than 1;The wood fiber's length-width ratios of 2～4 years of R.pseudoacacia all exceed 45.Therefore,2～4 years of such R.pseudoacacia is the most suitable paper making material,and the circulation period is determined as 3 years with a 99% reliability.

An anatomical study was conducted on the nutritive organs of Emmenopterys henryi.The results show that in the primary shoot and cortex of secondary shoot,pulp and root ′phloem of Emmenopterys henryi,many parenchyma cells are of obvious netted texture.Parenchyma cells of cortex and pulp are rich in primary structure of stem.The secondary xylem is diffuse-porous wood,vessel is simple perforation,end wall is slightly tilted,and there are few wood-parenchymatous cells.In old roots,there is no pulp in the center.The leaf is of dorsi-ventral leaf,wich developed palisade tissue,and stomata only scattering over the lower epidermis of leaf,which are the structural feature of mesophyte.

The effects of oxytetracycline on the morphology of the seedling with witches' broom and global DNA methylation level of Paulownia tomentosa × Paulownia fortunei were investigated.The results indicated that the infected seedlings by phytoplasma recovered to normal morphology of the healthy seedlings after being treated with more than 20 mg L~(-1) oxytetracycline,and the pathogen could not be detected with PCR in the seedlings.The global DNA methylation level of diseased seedlings was lower than that of healthy one.The oxytetracycline treatment was able to increase the DNA methylation level,and the methylation level of the diseased seedlings increased with the dose of applied oxytetracycline.However the increased methylation of infected seedlings with oxytetracycline treatment could still not reach to level of healthy seedling(CK),even the seedlings treated with lethal oxytetracycline concentration.

The results of structural botanical experiment on stem and leaf of Magnolia biloba(Rehd.et Wils.) Cheng show: there are secretory cavities distributed in the cortex and pith of the stem,of the rachis and the petiolule,and in the parenchyma under the main vein in the Magnolia biloba(Rehd.et Wils.) Cheng;in the walls of some cells there exist reticulate structures.The leaf is of dorsi-ventral leaf,and the stoma only scatter over the lower epidermis of the leaf,which belongs to anomocytic type.In the primare of the stem,the living thin-wall cells are very rich in the cortex and the pith.The secondary xylem is that of diffuse-porous wood.The vessel end wall,applanate and slopping is ladder-shaped compund fenestrated.The wood parenchyma is rare and has a star-scattering distribution.All these indicate that Magnolia biloba(Rehd.et Wils.) Cheng is a more primitive species in evolution.

The length,width,wall thickness,lumen diameter,the ratio of length to width,and the ratio of wall to lumen of the branch wood fiber of six paulownia species were analysed.Variance analysis and multiple comparison show notable variations between the wood fibers of the six paulownia species,namely P.elongate with the longest wood fiber,P.9502 and P.australis with the widest wood fiber,P.9502 and Paulownia tomentosa × P.fortunei 33 with the largest wall thickness,P.tomentosa with the lowest lumen diameter,P.elongate has the highest ratio of length to width,and P.tomentosa with the highest ratio of wall to lumen.Their applications depend upon their different characteristics of wood fibers.

<正>实践教学的现状目前,普通高等院校的实践教学基本上是根据专业教学计划模式来组织教学工作。实践教学环节主要包括实验课、课程实习和毕业实习3个方面。实验课是在教学规定的时间进行,大多是由老师按照指导书讲,学生按指导书上的步骤,

The ancient Ginkgo population in Funiu Mountain in the west of Henan Province distributes to the south of the top of Funiu Mountain, where there are old geology, warm climate, superior environment and many kinds of Ginkgo from Paleozoic. The local have the intense sense of protecting the old trees and most villages are named as Ginkgo. From then on lots of ancient Ginkgo have still live in few people hillside.The population structure approach to nature and jamming is slight which account for the ancient Ginkgo population in the west of Henan Province maybe the nature multiplication of the ancient Ginkgo.

The results of structural botanical experiment of top buds of P.tomentosa seedlings showed: with the change of the climate from fall to winter,the volume of the top buds of P.tomentosa decreased notably,while the density of the apical meristem cells increased significantly and the cell wall contracted inward.These changes indicated that,with the transformation of the climate from fall to winter,the vitality of the top buds of P.tomentosa descended gradually because of the environment stress,which lead to the death of the top buds ultimately.

The characteristics of flower bud differentiation of different kinds of germplasm resources of peach were studied by using paraffin section method; materials included Prunus kansuensis, P. ferganensis and P. persica. The results indicated that the flower bud differentiation process of different peach species was unanimous. The process included five phases: flower bud differentiation initiation phase, sepal differentiation phase, petal differentiation phase, stamen differentiation phase and gynoecia differentiation phase. Different peach species had different initiation period of flower bud differentiation. Flower bud differentiation of P. kansuensis started in early to mid June, earlier than that of others. However, flower bud differentiation of P. ferganensis and P. persica, started in late June to early July. The development phases of megagametophyte of P. kansuensis, P. persica ferganensis and P. persica weren't unanimous. P. kansuensis went through the winter in the form of ovule anlagen, while the other species shaped ovule anlagen in the next spring.

The study shows that the leaf of Cercidiphyllum japonicum is of dorsi-ventral leaf, with developed palisade tissue, and the stomata only scattering over the lower epidemis of the leaf. The scondary xylem of the stem is that of diffuse-porous wood. The vessed end wall, applanate and slopping,is ladder-shaped compound fenestrated. The wood parenchyma is rare. All these indicate that Cercidiphyllm japonicum is a more primitive species in evolution. There pellet matter distributed in the secondary cortex of old roots, and in the ray parenchyma.

The induction of embryogenic calli, somatic embryogenesis and plantlet regeneration from leaves and nodal segments of two genotypes of paulownia plants were studied. The results indicated that the optimal media of embryogenic callus induction from leaves and nodal segments of P. fortunei were MS+03mg/L NAA+14mg/L BA and MS+03mg/L NAA+8mg/L BA respectively,and those media of embryogenic callus induction were MS+03mg/L NAA+ 17mg/L BA. The capability of somatic embryogenesis from leaves of two genotypes of paulownia plants was higher than that from the nodal segments.

The leaf is isobilateral,the stoma is quadrilateral and only distributes in lower epidermis. Thirteen veins line in the mesophyll,alternating bigger vein and smaller one.On epidermis of the stem a thick golden colour cuticle on its exterior cousists of smaller flat rectangular or ellipsoidal cell. There are 23 collateral closed bundles scattered in the ground tissues. The velamon consists of 4-6 layers of parenchymal cells. Each of the endodermis, exodermis and pericyele consists of a layer of sclerenchymal cells alternating orrangement with parenchymal passage cells. Rodial wascular bundle is of hexarch without pith.

以叶片为材料,研究了悬铃木的体细胞胚胎发生及其植株再生.结果表明,悬铃木幼苗叶片在WPM+0.1mg·L-1BA+5.0 mg·L-1BA培养基上的愈伤组织诱导率和胚性愈伤组织诱导率分别为100%和89.1%;25℃的温度有利于胚性愈伤组织在WPM+0.5 mg·L-1BA培养基上进行体细胞胚胎发生;黑暗低温处理(10℃)3d不但可以促进体细胞胚胎的发生过程,而且可以提高其发生频率.

以中牟5号大蒜根尖为外植体,在11种固体培养基上诱导愈伤组织,筛选出最佳培养基MS+2,4-D 0.5 mg/L和MS+2,4-D 2.0 mg/L+KT 0.5 mg/L.愈伤组织形成后在上述11种培养基上继代3～4次,获得胚性愈伤组织后再转至液体培养基中,经强化培养3个月后获得胚性细胞悬浮系.试验结果表明:缩短换液时间(每隔3～4天换液1次),可加快胚性细胞悬浮系的建立.

There are secretory cavities distributed in the cortex and pith of the stem,of the rachis and the petiolule,in the secondary cortex of the old root,and in the parenchyma under the main vein,but not in the young root,in the Tapiscia sinensis. In the primare of the root, the endodermis has no clear.Casparian srip. According to the number of the xylem bundles, different side roots are triarach,pentarch and hexarch separately.In the primare of the stem, the living thin-wall cells are very rich in the cortex and the pith.The secondary xylem is that of diffuse-porous wood.The vessel end wall,applanate and slopping is ladder-shaped compund fenestrated.The wood parenchyma is rare and has a star-scattering distribution.All these indicate that Tapiscia sinensis is a more primitive species in evolution.The leaf is of bifacial.Stomata only scatter over the lower epidernis of the leaf, which belongs to anomocytic type 9(Ranunculaceous type).The structural characteristics of the leaf are those of the mesomorphic leaf.