A 13CO2 Enrichment Experiment to Study the Synthesis Pathways of Polyunsaturated Fatty Acids of the Haptophyte Tisochrysis lutea

The production of polyunsaturated fatty acids (PUFA) in Tisochrysis lutea was studied using the gradual incorporation of a ¹³C-enriched isotopic marker, ¹³CO₂, for 24 h during the exponential growth of the algae. The ¹³C enrichment of eleven fatty acids was followed to understand the synthetic pathways the most likely to form the essential polyunsaturated fatty acids 20:5n-3 (EPA) and 22:6n-3 (DHA) in T. lutea. The fatty acids 16:0, 18:1n-9 + 18:3n-3, 18:2n-6, and 22:5n-6 were the most enriched in ¹³C. On the contrary, 18:4n-3 and 18:5n-3 were the least enriched in ¹³C after long chain polyunsaturated fatty acids such as 20:5n-3 or 22:5n-3. The algae appeared to use different routes in parallel to form its polyunsaturated fatty acids. The use of the PKS pathway was hypothesized for polyunsaturated fatty acids with n-6 configuration (such as 22:5n-6) but might also exist for n-3 PUFA (especially 20:5n-3). With regard to the conventional n-3 PUFA pathway, Δ6 desaturation of 18:3n-3 appeared to be the most limiting step for T. lutea, “stopping” at the synthesis of 18:4n-3 and 18:5n-3. These two fatty acids were hypothesized to not undergo any further reaction of elongation and desaturation after being formed and were therefore considered “end-products”. To circumvent this limiting synthetic route, Tisochrysis lutea seemed to have developed an alternative route via Δ8 desaturation to produce longer chain fatty acids such as 20:5n-3 and 22:5n-3. 22:6n-3 presented a lower enrichment and appeared to be produced by a combination of different pathways: the conventional n-3 PUFA pathway by desaturation of 22:5n-3, the alternative route of ω-3 desaturase using 22:5n-6 as precursor, and possibly the PKS pathway. In this study, PKS synthesis looked particularly effective for producing long chain polyunsaturated fatty acids. The rate of enrichment of these compounds hypothetically synthesized by PKS is remarkably fast, making undetectable the ¹³C incorporation into their precursors. Finally, we identified a protein cluster gathering PKS sequences of proteins that are hypothesized allowing n-3 PUFA synthesis.     

60Co-γ射线辐照对黄牡丹种子萌发及幼苗生长的影响*

  对黄牡丹种子进行不同剂量的60Co-γ射线辐照处理,以未照射种子为对照, 观测辐照对种子生根、萌发及幼苗生长的影响。结果表明:种子生根率和萌发率随辐照剂量增加而降低,高剂量(100Gy以上)对种子萌发和幼苗生长有显著的抑制作用（P<005）,辐照的剂量与幼苗存活率呈负相关,且幼苗表型性状各不相同。根据试验数据以及回归分析确定黄牡丹种子的临界剂量为485Gy,适宜剂量范围为40～60Gy。     

黄牡丹花粉和植株形态性状关联性的研究

通过对6个不同居群的黄牡丹花粉形态进行扫描。结果显示,花粉形态具有多样性,花粉外壁纹饰有脑纹网状、皱波网纹状、粗网状、网状和穴状细网5种;花粉粒的变幅为(32.94-48.87)μm×(21.57-29.70)μm,居群花粉在极轴、赤道轴和极赤比都存在显著差异。通过对6个花粉形态指标和植株11个外部形态指标进行相关性分析。结果表明,花粉极轴与叶长宽比、极赤比与叶长宽比呈明显正相关,花粉极轴与叶长柄比、极赤比与叶长柄比呈明显负相关;花粉外壁纹饰变化与花瓣数量、宿存花萼和苞片数量呈显著相关。依据花粉外壁纹饰的演化规律可推测,花瓣数少、宿存萼片少,苞片数多、叶长宽比越大、叶长柄比越小应是植株较进化的特征。     

Hip dysplasia and dog breeding

Summary

Hip dysplasia is considered to be one of the most serious problems in dog breeding. In the past 20 years the studies of, and the attempts to control, this condition have been directed mainly to the overall picture of the abnormality of the hips. The various efforts have resulted in a decrease in the incidence of HD in several breeds of dogs. For other breeds the results have not been very convincing, however. In some instances they are even said to be conflicting with other aims of breeding. Based on these data some separate studies have recently been performded in respect of the details of the disorders in the hip joints and of the heritability of these elements.

The present study concerns itself with the roots of the disorders as they are observed in the various breeds. A great variety of data indicates that selection within the canine species for specific morphological traits must be considered as one of the most important roots of the occurrence of HD. The collected data strongly indicate that improvements in the HD status in the various breeds can be reached by selection against specific disorders of the hip joints in these breeds.     

脱毒地黄低成本快繁技术探讨

对地黄试管苗快繁的培养基成分进行改良,同时使用一些药品的廉价替代品,可使试管苗快繁生产成本降低47%左右;试管快繁和常规育苗技术相结合提高了繁殖系数,相对降低了脱毒地黄种子的成本,为地黄工厂化生产和基地化建设提供了有利条件。     

洞庭湖区3种野生食用真菌生境调查与鉴定

为了解和开发洞庭湖区野生真菌资源,对采自大通湖区芦苇湿地的3种野生可食用真菌进行生境调查与鉴定。调查发现,3种真菌形态各异,对生长条件与季节具有不同的适应性和温型偏好,其中HEFIW LuI子实体较小,菌盖黄褐色,多丛生,适温较广,生长周期长;HEFIW LuII子实体中等大,菌盖乳白至淡黄色,适温偏低,多发生于早春时期;HEFIW LuIII子实体中等至较大,菌盖淡黄至浅褐色,适温偏高,多发生于春末夏初时期。通过形态观察和ITS测序,鉴定3种真菌分别为硫黄鳞伞(Pholiota conissans)、田头菇(Agrocybe praecox)和浅黄皱环球盖菇(Stropharia rugosoannulata f. lutea)。     

安康漆树叶(虫甲)危害的现状及对策

漆树叶虫甲在安康市发生的区域越来越大,传播速度很快,大爆发的频率越来越高。主要危害特征是:苗期危害严重;叶部危害重于枝干;纯林危害重于混交林;人工林重于天然林。根据其在安康市发生的特点及特征提出了以加强科学的营林措施和预测预报工作、加大种苗检疫力度以及采用化学、生物和人工防治等有效控制手段。     

Ghrelin在绵羊黄体形成过程中的表达

黄体作为卵巢上主要功能单位之一,对维持哺乳动物正常生殖的作用至关重要,而Ghrelin在调节能量平衡等多种生物学功能的积极作用,促使我们探讨Ghrelin在绵羊有腔和成熟卵泡内壁层颗粒细胞形成黄体后的表达情况,结果表明发情期黄体细胞的免疫活性远强于其前身壁颗粒细胞,而且Ghrelin mRNA相对表达量也显著高于其前身壁颗粒细胞.Ghrelin免疫活性和mRNA水平的黄体形成前后的显著变化间接的表明这一新型分子对于黄体功能变化具有潜在调控作用.     

A protective role of resveratrol against the effects of immobilization stress in corpora lutea of mice in early pregnancy

In the present study, we aimed to investigate a protective role for resveratrol against the effects of immobilization stress on corpora lutea(CL) of mice in early pregnancy. A total of 45 early-pregnant mice were divided into no immobilization stress(NIS) group, immobilization stress(IS) group, and immobilization and resveratrol treatment(IS+RES) group(n=15). Mice were immobilized in plastic tubes(50 mL) for 3 h per day during day 1 to 7 of pregnancy. In the IS+RES group, 5 mg kg–1 d–1 of resveratrol was administered just prior to application of stress. We analyzed apoptotic activity in CL by Western blotting analysis(WB), transmission electron microscopy(TEM), and immunohistochemistry(IHC). Serum progesterone levels were examined with radioimmunoassay(RIA). IHC results showed that the intensity of positive staining for Bax was increased, and for Bcl-2 was decreased in CL after IS, while resveratrol treatment reversed the positive staining for Bax and Bcl-2. WB revealed that immobilization stress up-regulated the expression of Bax and caspase-9, and downregulated Bcl-2 expression, while resveratrol treatment attenuated the effects of immobilization stress on the expression of Bax, Bcl-2 and caspase-9. According to our TEM results, apoptosis as defined by chromatin condensation was found in CL after immobilization stress, while resveratrol inhibited the apoptosis. We also demonstrated that immobilization stress decreased progesterone concentrations and ovarian expression of StAR, while resveratrol restored the concentrations of progesterone and expression of StAR back to normal. These results indicated that immobilization stress induced luteal regression while resveratrol inhibited luteal regression, suggesting that resveratrol plays a protective role on corpora lutea of mice during early pregnancy.     

Influence of one selected Tisochrysis lutea strain rich in lipids on Crassostrea gigas larval development and biochemical composition

Effects of a remarkably high overall lipid Tisochrysis lutea strain (T+) upon gross biochemical composition, fatty acid (FA), sterol and lipid class composition of Crassostrea gigas larvae were evaluated and compared with a normal strain of Tisochrysis lutea (T) and the diatom Chaetoceros neogracile (Cg). In a first experiment, the influence of different single diets (T, T+ and Cg) and a bispecific diet (TCg) was studied, whereas, effects of monospecific diets (T and T+) and bispecific diets (TCg and T+Cg) were evaluated in a second experiment. The strain T+ was very rich in triglycerides (TAG: 93–95% of total neutral lipids), saturated FA (45%), monounsaturated FA (31–33%) and total fatty acids (4.0–4.7 pg cell^?1). Larval oyster survival and growth rate were positively correlated with 18:1n‐7 and 20:1n‐7, in storage lipids (SL), and negatively related to 14:0, 18:1n‐9, 20:1n‐9, 20:4n‐6 and trans‐22‐dehydrocholesterol in membrane lipids (ML). Surprisingly, only the essential fatty acid 20:5n‐3 in SL was correlated positively with larval survival. Correlations suggest that physiological disruption by overabundance of TAG, FFA and certain fatty acids in larvae fed T+ was largely responsible for the poor performance of these larvae. ‘High‐lipid’ strains of microalgae, without regard to qualitative lipid composition, do not always improve bivalve larval performance.