子囊具四个孢子的皱赤壳属一新种

描述了分布于中国热带、亚热带地区的丛赤壳科皱赤壳属Rugonectria一新种。对中国材料进行形态学和DNA序列分析相结合的研究表明,它们与日本报道的栗生皱赤壳R. castaneicola较为接近,但存在形态学和DNA序列上的明显差异,代表该属一个新种。     

Comparison of Worm Control Strategies in Grazing Sheep in Denmark

Control of nematode parasites with reduced reliance on the use of anthelmintics was studied in 16 ewes with suckling twin lambs on contaminated pasture in Denmark. Ewes and lambs were treated with albendazole at turn-out 3 May. Ewes were removed from the groups on 26 July, and lambs were slaughtered on 11 October. The animals were allocated to 4 groups of 8 lambs and their 4 ewes. Group TS was treated with albendazole at weeks 3, 6 and 8 after turnout and set-stocked; group TM was similarly treated but moved to clean pasture in conjunction with the last drenching; group US was untreated and set-stocked, and group UM was left untreated but moved to clean pasture week 8 after turn-out. Supplementary feed was offered in June and August due to scarcity of pasture. Strategic treatments of ewes and lambs weeks 3, 6 and 8 after turn-out, with or without a move to clean pasture, were highly effective in controlling nematode infections for most of the season. This was reflected in better weight gains and carcass characteristics in the treated compared to untreated lambs, resulting in an average increase in the value of the product by 36%. The effect of moving without treatment (UM) on faecal egg counts was limited but peak pasture infectivity was reduced to less than 10% compared to the set-stocked group and weight gains of lambs were significantly better despite poor feed availability in late season. The study showed that under set-stocked conditions repeated anthelmintic treatments of both ewes and lambs in early season may ensure sufficient nematode control whereas moving animals to clean pasture without dosing was less efficient. The latter may, however, still be a viable option in organic and other production systems where routine use of anthelmintics is banned, particularly if weaning and moving are combined or a second move is performed.     

鼠疫耶尔森氏菌LcrV基因的克隆及序列分析

为了研究鼠疫耶尔森氏菌（Y.pestis）保护性抗原V蛋白,从基因库中查得Y.pestis LcrV基因DNA序列,针对序列设计合成了一对PCR扩增引物,以本所保存的Y.pestis菌种为模板进行基因扩增,结果获得长约980bp的DNA片段。将扩增产物回收纯化,克隆至pGEM-T载体,构建重组载体pGEN-T/ypV,经过PCR,酶切鉴定,并对pGEM-T/ypV中的V基因片段进行测序,分析测序结果与己知序列相同,表明获得了LcrV基因。     

四数獐牙菜的胚胎学及其系统学意义

四数獐牙菜花药四室,药壁发育为双子叶型;绒毡层腺质型。小孢子母细胞减数分裂为同时型, 四分体的排列方式为四面体形;成熟花粉为3-细胞。子房2心皮,2心皮连接处强烈内凸,4列胚珠。薄 珠心,单珠被,直生胚珠。胚囊发育为蓼型。胚乳发育为核型。胚胎发育为茄型酸浆I变型。反足细胞 在胚囊成熟时期宿存。果实成熟时,种子只发育至球型胚阶段。承珠盘存在。与已研究的獐牙菜种类 的胚胎特征相比较,该种存在三个显著的特点：直生胚珠,心皮连接处强烈内凸,承珠盘存在。这三个特 征目前仅在龙胆族中的花锚属中发现。经过性状分析,它们均是演征,此三个共有演征表明四数獐牙菜 与花锚属是一单系群,它们的亲缘关系最近。这与Yun &; Kupfer(1995)的分子证据部分吻合,因为分 子系统树上的花锚单系支包括花锚、四数獐牙菜和北美的密花属(广义獐牙菜属中的密花组),而后者的 胚胎学特征未有任何报道。胚胎学研究暗示四数獐牙菜的分类学等级有待重新评价,广义的獐牙菜属 有可能不是一单系发生群。     

Restriction analysis and sequencing of the ITS regions and 5.8S gene of rDNA of Ganoderma isolates from infected oil palm and coconut stumps in Malaysia

Use of Crassulacean acid metabolism (CAM) plants in México and worldwide has a long history, but the morphological and photosynthetic aspects of these plants have only been considered recently. Emphasis in this article is on the daily net CO₂ uptake ability by three species of agaves and three species of cacti that are currently extensively cultivated in México for beverages, food, fodder, and forage ‐ Agave mapisaga, A. salmiana, A. tequilana, Opuntia ficus‐indica, O. robusta and Stenocereus queretaroensis. Data under controlled conditions are used to help interpret seasonal net CO₂ uptake patterns observed in the field. These CAM plants have instantaneous and total daily net CO₂ uptake values similar to those for highly productive C₃ and C₄ crops. The future increase in the cultivated area of CAM plants will have both agronomical and ecological ramifications because of the ability of these plants to endure prolonged drought and to sequester carbon during extended dry periods when few C₃ and C₄ crops and non‐CAM native plants can fix atmospheric CO₂.     

Changes in Activity of Choline Acetylase in Central Nervous System of Rat after Intraventricular Administration of Noradrenaline

APPLICATION of strychnine or d-tubocurarine to the exposed cerebral cortex leads after a few minutes to abnormality in somatosensory evoked potentials^1,2. This consists of a surface negative wave (peak latency, 21–23 ms) which attains an amplitude five to twenty times greater than that of the normal evoked potentials and probably reflects excessive depolarization of the apical dendrites of pyramidal neurones. We wish to report the blocking of this effect by prior application of eserine to the cortex.     

The Effect of Current Photosynthesis on the Origin of Translocates in Old Tomato Leaves

The rate of carbon transport from an old tomato leaf (54 days),grown at 80 W m^–2, was measured under light flux densitiesbetween 7 and 90 W m^–2. Under low light, the rate of carbontransport over a 6 h period was about 1 mg C dm^–2 h^–1,well in excess of the concurrent photosynthetic rate. The lossfrom these leaves of ¹⁴C-leaf assimilate which was fixed beforethe experimental period amounted to 62 per cent of the totalinitial uptake and was higher than that from leaves with higherconcurrent photosynthetic rates. The higher loss of ¹⁴C fromleaves with low photosynthetic rates was due to a greater contributionof ¹⁴C from the starch and residue fractions. The rate of transportappeared to be determined by the concentration of the labilesucrose, not the total sucrose concentration. In comparisonwith young fully-expanded tomato leaves (Ho, 1976) the sizeof the labile sucrose pool appeared to decrease with age. Thephotosynthesistranslocation coefficient was low (k₁k₂=0•21)for an old tomato leaf. Based on these results a scheme of carbonpartitioning in relation to translocation is proposed. Criteriafor assessing the efficiency of translocation in leaves arediscussed.     

Investigation of Bidirectional Movement of Tracers in Sieve Tubes of Salix Viminalis L.

Sieve-tube sap was collected as honeydew from the aphid Tuberolachnussalignus (Gmelin) feeding on a young shoot or a mature stemof willow (Salix viminalis L.). Two radioactive tracers (either³H-glucose and ¹⁴C-sucrose, or ¹⁴CO₂, Na₂ ¹⁴CO₃, and ³²P-orthophosphate)were applied to leaves or to bark abrasions at each end of thestem. In some experiments the tracers were applied after thestart of honeydew production, whilst in others the tracers wereapplied before the aphids were sited. In most cases aphids feeding between the tracer applicationpoints produced doubly-labelled honeydew during a 24–48-hperiod from tracer application. In some instances the firstdrops of honeydew contained one tracer, followed several hourslater by the other tracer, whilst some aphids produced doubly-labelledhoneydew from the first drop. Singly-labelled or inactive honeydewwas found in only a few cases. It was demonstrated that when ³H-glucose and ¹⁴C-sucrose wereapplied at opposite ends of a stem that the tracers moved inopposite directions in the form of sucrose. The data suggest that a simultaneous bidirectional movementof two tracers may occur in the same sieve tube. However, thepossibility that the doubly-labelled honeydew could be producedby lateral movement from one sieve tube carrying one tracerto an adjacent punctured sieve tube carrying the other tracercannot be discounted.     

An Effect of Ethylene on the Distribution of 14C-sucrose from the Petals to Other Flower Parts in the Senescent Cut Inflorescence of Dianthus caryophyllus

The distribution of carbon-14 in the flower parts of the cutcarnation inflorescence after feeding ¹⁴C-sucrose through thepetals was studied during natural ageing and after ethylenetreatment. Levels of ethylene which caused irreversible wiltingof petals also promoted an accelerated transfer of the radioactivesucrose to the nectar, gynaecium and stem. Since the nectarreceived a relatively large proportion of the radioactive carbon,the composition of the sugars in the nectar and the vascularizationof the nectary were investigated. Sucrose comprised about 85per cent of the nectar sugars and the balance was glucose andfructose. The vascular tissue closest to the nectary consistedof phloem elements; tracheary elements terminated deeper inthe receptacle and were surrounded by a ring of phloem. Thepercentage of solutes in the nectar was about 18 per cent andincreased when the flowering stems were placed in sucrose solutions;the solutes in the nectar were principally sugars. Taken togetherthe results show that the nectary can act as a sink for sucroseand, in the flower at least, that translocation of sucrose takesplace in the phloem. The results provide further evidence forthe hypothesis that ethylene promotes mobilization of substrateand an efflux of material from petals to the gynaecium, nectarand stem.