Morphogenesis of the fern protonema

Summary At the apex of the protonema ofDryopteris varia, a club-shaped papilla is differentiated after the protonema was segmented into six or seven cells in the normal development. If the sporeling is reared in medium containing IAA, formation of the apical papilla is much accelerated to take place at two- or three-cell stage when the concentration of IAA is 1 to 0.01 ppm. But if it is reared in a medium of a higher concentration of IAA, 10 to 100 ppm, the same apex differentiates a rhizoid. That is to say, it depends upon quantitative relations of auxin as to whether the apex of protonema forms a papilla or a rhizoid. With 3 Figures     

Note on Rashevsky's equation for cellular growth

The equation for growth by intussusception involves the product of the internal concentrations ofn metabolites. This products is shown, in general, to satisfy a certain algebraic equation of then-th degree. Approximate solutions are exhibited for a somewhat wider class of cases than are considered by Rashevsky.     

Development of the protonema and bud formation in mosses

In the course of their development the protonemata of Funaria hygrometrica produce two different substances which diffuse into the substrate. In the chloronema a thermo-labile growth-promoting substance is formed. In the caulonema, after about 10 days, a substance is produced which is thermostable and soluble in amyl alcohol, which can be dialysed, and which functions as a growth inhibitor. Both substances also influence bud formation. This is at an optimum only when there is a certain balance between these two substances.
This promotion is fundamentally different from that brought about by treatment with kinetin, because kinetin can function only as an additional factor in promoting bud formation. Very probably it acts as an agent which creates centres of attraction toward which morphogenetic substances are drawn. This assumption is supported by the fact that kinetin cannot be transported and therefore has no 'after-effect'. It probably functions only in the caulonema cell it penetrates. It converts every caulonema cell into a 'reaction cell'.     

Observations on dividing plastids in the protonema of the moss Funaria hygrometrica Sibth.

The process of division was investigated in the different types of plastids found in the tip cell of the protonema of Funaria hygrometrica Sibth. There were no structural changes in the envelope membranes of any of the plastid types during the initial stage of division. As the process of constriction advanced, thylakoids were locally disintegrated and sometimes starch grains in the isthmus were locally dissolved. In the isthmus, tightly constricted plastids were characterized by an undulating envelope and an increasing number of vesicles. After three-dimensional reconstruction of electronmicrographs a distinct filamentous structure was observed in the plane of division outside the plastid but close to the envelope. At different stages of division the constricted regions were partly surrounded by one or a few filaments. The roundish plastids in the apical zone were accompanied by single microtubule bundles, and the spindle-shaped plastids in the cell base were surrounded by single microtubules and microtubule bundles. A model of co-operation between microtubules and the filamentous structure in the division process is discussed.A preliminary report was presented at the Tagung der Deutschen Botanischen Gesellschaft und der Vereinigung für Angewandte Botanik, Hamburg, September 1986     

Cytokinin-induced activation of polyribosomes in the protonema of Ceratodon purpureus

A ribosomal preparation from N⁶-isopentenyladenine-treated protonema of Ceratodon purpureus (Hedw.) Brid. exhibited an increased activity of protein synthesis in a cell-free system as compared to a control preparation. The ratio of polyribosomes to monoribosomes was the same in both preparations, and it is assumed that an activation of pre-existing polyribosomes was responsible for the increased efficiency in protein synthesis. An electrophoretic fractionation of the in vitro translation product showed an enhanced synthesis of some polypeptide fractions in the cytokinin variant.     

On the formation of protonema ofDrummondia sinensis of the orthotrichaceae

In the present study, the mode of formation of the protonema ofDrummondia sinensis is recorded and the relationship between the sporeling type as a response to ecological adaptation is discussed. A spore germinates inside the stretched exospore, and later forms a massive protonema consisting of 8–20 cells. Soon after, the stretched spore coat ruptures and a mass of 5–6 cells protrdes from the broken exospore. In this species neither chloronema nor caulonema could be observed, although such is often seen in other species of Bryales. An initial cell of the leafy shoot is formed from the apical cell of the massive protonema.     

Behavior of amyloplasts in photo- and gravitropism of the moss protonema

The protonema of mosses Ceratodon purpureus and Pottia intermedia is negatively gravitropic in darkness and grows on the substrate surface under illumination. However, the putative mechanisms of these growth responses are not well understood so far. For gravitropism, sedimentation of amyloplasts has been widely assumed to be the first step of the signal transduction chain. This model was supported by numerous observations where amyloplasts' number or size in a protonema apical cell correlated with its gravisensitivity. Unlike multicellular graviperceptive organs, a protonema apical cell is the same site for both of gravity and light perception and realization of growth movements. In addition, red light is known to change the cell responses to gravity. Therefore, we analysed the influence of red light on the events associated with graviperception and growth movements of protonema apical cells, namely: plastid behavior, size, and number, starch content, chlorophyll fluorescence intensity and alpha-amylase activity, under gravistimulation of dark-grown protonema.     

Environmentally induced formation of plasmatic filaments in the protonema ofCeratodon purpureus

Summary Incubation of spores ofCeratodon in 0.1% sucrose solution in darkness causes the formation of abundant filamentous bundles with an average width of 0.39±0.02 . The center-to-center distance of adjacent filaments is 216±1.4 Å. The individual filaments have an electron-dense tubular part with a diameter of 108±0.6 Å. Dictyosome-derived coated vesicles, which enlarge to ER-like coated tubuli, are always associated with the filaments. In younger cultures these electron-dense coated tubuli seem to spin filaments from their sides.     

Multiple DNA contents in the haploid protonema of the mossFunaria hygrometrica sibth

Summary Cytofluorometry with fluorochrome Hoechst 33258 shows that caulonema cells in the protonema of the haploid mossFunaria hygrometrica endoreduplicate their DNA up to 8 or 16 C during normal development. The increase in DNA content depends on age and position of the cells in the filament and occurs in those cells, which normally do not undergo any further growth or division.Single cells from different positions between the tip and the tenth cell of the filament were isolated and regenerated to new protonema. Groth and differentiation of these regenerates depend on the age and position of the original cell. Cytofluorometry of the tip cells of these regenerates shows, that the higher DNA content is maintained during regeneration.     

普通裂褶菌真菌学及实验室研究进展

普通裂褶菌是一种条件致病菌,可侵犯人体多个器官多种组织,导致各种表现形式的疾病,如脑脓肿、脑膜炎、鼻窦炎、肺部真菌球、蜂窝肺、肺结节、甲真菌病等.由于普通裂褶菌感染引起的真菌病病例少见报道,临床医生对其认识不足,再加上某些实验室不具备鉴定条件,所以感染该菌的病例常被漏诊、误诊.现将近年来临床分离的普通裂褶菌株真菌学及实...     

Uptake, transport and metabolism of cytokinin in moss protonema

Uptake, transport and metabolism of cytokinin in the protonemaof Funaria hygrometrica were studied using labelled kinetin(6-furfurylamino [8-¹⁴C]-purine). All cells of the protonema,chloronema and caulonema, were able to take up kinetin, whichwas carried in the symplastic transport system from cell tocell. Radioactivity was especially accumulated in growing cellsof the protonema. Kinetin was metabolized immediately afteruptake. While only very little kinetin (less than 1%) remainedas free kinetin and one part was immobilized in chromatographicseparation [e.g. attached to proteins and incorporated intonucleic acids (17)], most of the remaining kinetin was metabolizedto adenine derivatives. Exogenously supplied adenosine changedthe metabolism of kinetin. In the caulonema, adenosine reducedthe turnover of kinetin to other adenine derivatives and enhancedthe content of labelling in the start fraction. Thus adenosinecan stimulate cytokinin-dependent bud formation in moss protonema. (Received November 24, 1977; )     

Trehalase in Schizophyllum commune

Summary The hydrolytic enzyme trehalase was demonstrated in mycelial extracts of Schizophyllum commune cultured on either glucose or trehalose as sole source of carbon and energy. The enzyme was also detected in culture-filtrates of trehalose-grown cells. The intracellular forms of trehalase from glucose- and trehalose-cultures were similar in their response to dialysis and heat treatment as well as pH optimum, affinity constant for trehalose and resistance to a variety of sugar alcohols.     

不同培养基及酶对立碗藓原丝体的作用研究

采用含不同成分的MS培养基处理立碗藓的原丝体,发现随蔗糖浓度的提高原丝体的生长相对趋于老化;当培养基中附加不同浓度的2,4-D和6-BA 时,10日龄的原丝体出现了明显变化,当二者浓度均为0.5 mg*L-1,幼嫩的原丝体上能长出疏松易碎的白绿色愈伤组织.利用1%纤维素酶和0.8%的果胶酶分别处理10日龄、20日龄的原丝体和10日龄的茎叶体的叶片2～10 h,结果发现10日龄的原丝体在酶解2 h后能游离出大量的原生质体;而20日龄的原丝体效果较差,只能游离出极少量的原生质体;对于10日龄的茎叶体酶解10 h仍看不到原生质体游离出来.这表明立碗藓原丝体对不同的外界条件可产生不同的反应,但原丝体的生理状态不同对激素和酶类的反应具有非常显著的差别.