A REINTERPRETATION OF THE ONTOGENY OF THE ASCOCARP OF SPECIES OF THE ERYSIPHACEAE

A study of four species of Erysiphaceae (Uncinula salicis, Podosphaera leucotricha, Erysiphe cichoracearum, and Microsphaera diffusa) revealed that the binucleate stages of the ascocarp are initiated in a similar manner to those of Diporotheca rhizophila Gordon & Shaw. The “appendages” developing on immature ascocarps are considered to be receptive hyphae. Appendages characteristic of mature ascocarps are produced much later. Lysis of certain centrum cells occurs, and asci are initiated from some of the remaining binucleate centrum cells. Resorption of centrum cells by the asci is supported by this investigation, corroborating Björling's earlier studies on Erysiphe graminis.     

EFFECT OF CYCLOHEXIMIDE ON THE CELL CYCLE OF THE CRYPTS OF THE SMALL INTESTINE OF THE RAT

A single injection of 1.5 mg/kg of cycloheximide induces a complete disappearance of mitotic activity in rat intestinal crypts within 1.5–2 hr. No significant necrosis of crypt cells is observed even though this phenomenon is accompanied by a marked decrease in uptake of labeled precursors into protein and DNA. Mitoses reappear 6 hr after injection and recovery then follows a cyclic pattern over a period equivalent to one cell cycle, thereby reflecting at least a partial synchronization of cell division. Concurrent use of colchicine, an agent known to induce metaphase arrest, has demonstrated that cycloheximide, while having no apparent effect on cells already in division, prevents the entrance of new cells into visible mitosis. Analysis of the cell cycle suggests that one block initiated by cycloheximide occurs in G₂, presumably as the result of an interference with the formation of protein(s) required for the normal progression of cells from this phase of the cycle into mitosis.     

INVESTIGATION OF THE STRUCTURE OF THE CORNIFIED EPITHELIUM OF THE HUMAN SKIN

To explore the submicroscopic structure of the human callus by the polarization optical method, serial sections were prepared in three principal planes and the sign of double refraction as well as optic axes of various regions of the sections was determined. It was concluded that in areas under the grooves keratin is oriented parallel to the surface plane of the callus and to the direction of the grooves. In component structures of ridge areas such as in sweat duct areas a circumferential, in cross-band areas a linear, and in other parts a random structure was seen. The cross-bands of ridge areas in association with groove areas revealed a regular lattice-like submicroscopic pattern which was considered as an important mechanical system of the cornified epithelium.     

THE LOCUS OF THE ACTION OF VERATRIN

1. In Mnemiopsis veratrin shows two stages of veratrin poisoning. First, inhibition of the beats of the plates which disappears on cutting them away either singly or in small groups. Second, after half an hour mechanical stimulation excites the beat of the plates in the intact veratrinized animal. It is concluded that veratrin acts on nervous tissue and not on the substance of the swimming plates. 2. In Lumbricus, veratrin acts on the ventral nerve cord alone, and not on the muscles and peripheral nerves. 3. In Musca, veratrin first causes opisthotonos, then spasms and extreme flexion of the legs. Decapitation causes these effects to disappear hence veratrin acts on the cerebral ganglia of the fly. 4. Veratrin applied to the sciatic nerve of the frog causes, after a latent period of 20 minutes, irregular contractions of the gastrocnemius which persist for an hour or more. Veratrin is thus a neurophil alkaloid of the first class as well as second and in this way resembles tetraethyl ammonium chloride. 5. If the end of a sciatic nerve is dipped into veratrin solution, then direct stimulation of the gastrocnemius muscle results in contraction with delayed relaxation, although the muscle itself is not subject to the action of veratrin. 6. By means of preparations of the sartorius muscle of the frog it is shown that veratrin acts not on the muscle cells directly but on the nerve fibers. Hence veratrin produces the characteristic muscle curve showing delayed relaxation by its action on the nervous elements.     

THE ULTRASTRUCTURE OF THE STALK AND BASE OF THE ANTHERIDIUM OF POLYTRICHUM

The fluorescent boundary across the stalk of an antheridium of Polytrichum appears as a distinctive, secondary wall layer in electron micrographs. Lamellations of electron-dense and -lucent materials cause this layer to resemble the “suberized lamellae” of root endodermis and leaf bundle sheaths in grasses. The cells of the stalk below the boundary are especially rich in lipid droplets, whereas those in the base of the antheridium, above the boundary, have markedly fewer and smaller lipid droplets and abundant rough endoplasmic reticulum often in loosely parallel arrays. Cytological differences develop before the boundary appears, so that the distinctive wall layer is secreted by protoplasts that are already specialized morphologically. During maturation of an antheridium there is a secretion of a fluid into a space that forms at the bottom of the sperm chamber. However, the cells surrounding this fluid show no special morphological adaptations that would seem to relate to secretion.     

生境破碎化对黑白仰鼻猴种群数量的影响

从1999年4月至2002年6月间,对黑白仰鼻猴种群的分布和生境状况进行了调查。与十年前的调查结果相比,本次调查新发现了4个猴群,但有5个以前存在的猴群已经消失,现存种群数量为13个猴群,总体数量约为1200─1700只。从西藏的芒康到云龙的龙马山,随着海拔的降低,猴群可利用的植被类型也随之多样化。但由于砍伐、放牧、开矿等因素的影响,猴群的适宜生境破碎化程度较高,连接猴群的生境走廊状况通常较差,多数猴群孤立分布,并且存在小种群问题,生境走廊的维护和恢复已成为该物种保护成功与否的关键。种群的总体数量下降了32%,其中4个猴群数量下降,4个猴群持平,1个猴群有所增长,5个猴群消失,这不容乐观的状况给我们的保护工作敲响了警钟。     

三峡库区甘井河水域牧场浮游植物群落结构及水质评价

为了解三峡库区的忠县甘井河段水域牧场生态渔业对水环境的影响, 于2013 年3、6、9 及12 月按季度对该河段4 个站点进行了浮游植物群落结构及水体理化因子的监测, 并采用生物多样性指数法和综合营养状态指数法对水体营养状况进行了评价。结果表明, 该河段浮游植物有7 门93 个属种, 其中绿藻门的物种数最多, 有37 种, 占浮游植物群落总数的39.79%, 其次为硅藻门和蓝藻门, 物种数分别为26 种和13 种,分别占浮游植物群落总数的27.96%和13.98%;浮游植物的年均丰度为757.67104 ind./L, 变化范围(3.065743.99)104 ind./L, 年均生物量为4.40 mg/L, 变化范围0.0317.67 mg/L;水体的年平均透明度为1.18 m, 叶绿素a、总磷、总氮含量分别为8.54 g/L、0.13 mg/L、1.95 mg/L;浮游植物香农多样性指数(H')、均匀度指数(J)年均值分别为2.90 和0.88, 全年综合营养状态指数值为37.5971.86, 由此推断, 甘井河水质属于中污染轻污染状态、中营养型富营养型。在鱼类生长旺季的6 月, 甘井河段养殖区内的水质优于非养殖区, 这可能与养殖区内放养滤食性鱼类有关, 证实了水域牧场没有带来水环境的污染, 反而能提高生物多样性, 在一定程度上改善了水体。       

THE ROLE OF THE SPLEEN IN THE REPOPULATION OF THE HAEMOPOIETIC SYSTEM OF HEAVILY-IRRADIATED MICE

The respective role of the spleen or of the bone marrow in the regeneration of the haemopoietic progenitor compartment of heavily-irradiated mice has been investigated. Splenectomy was used to this end in animals injected with exogenous isogenic cells or regenerating from endogenous spleen or marrow cells. Analysis of the data as a function of time shows that the presence of the spleen affects marrow CFU repopulation only at the early post-irradiation stages. The expansion of the marrow progenitor pool proceeds, however, rather independently of the spleen and marrow CFU remain eventually as the main source of haemopoietic cells in the surviving mice. Thus the reaction of the spleen may be envisaged as a fast, important but transient contribution to the overall haemopoietic function of heavily-irradiated animals.