Induction of Biplanar Growth in Fern Gametophytes

In constant white light, protonemata of different ages of Asplenium nidus produce a fixed number of cells before they become biplanar. Protonemata with a lower initial cell number require a longer time to become biplanar than those with a higher initial cell number. Increasing the photoperiod or the light intensity reduces the cell number in the filament at the time of initiation of biplanar morphology. It is suggested that inductive light acts directly on cell metabolism to induce biplanar morphology, rather than indirectly by inducing mitotic activity.     

In vitro Phytohormonal Regulation of Fern Gametophytes Growth and Development

Russian Journal of Developmental Biology - Interest in ferns as objects of biotechnological research is determined by the characteristics of their development and reproduction, which is important...     

Dark Growth and the Associated Phenomenon of Age-dependent Photoresponses in Fern Gametophytes

The cross-sectional area of the growing tip of a fern filamentundergoes an age-dependent decline over the period of darknessthat precedes an experimental light treatment. This dark-mediateddecline accounts for the appearance of age-dependent responsesto light treatments. Moverover, monochromatic irradiation experimentsshow that the cross-sectional areas of filaments do not manifestsignificant age-dependent variation in response to light treatmentsof sufficient energy. Because it is the cross-sectional arearather than the elongation rate that exhibits the direct responseto light in the control of filament growth, it follows thatthere is no evidence for age-dependent changes in photosensitivityof the filaments. Regression analyses establish that pre-germinationlight treatments do not affect subsequent patterns of dark growth;instead, stress calculations suggest that the tapering of thecross-sectional area may be referable to a state of stress-straindisequilibrium within the filament tip. These and other characteristicsof age-dependent growth responses of fern filaments are summarizedin a general working model. fern gametophytes, age-dependent photoresponses, stress analysis, Onoclea sensibilis     

Growing and Embedding Fern Gametophytes for Autoradiographic Studies

Fern gametophytes were grown in liquid medium on the surface of plastic tissue culture flasks (Falcon Plastics) where they remained attached through radioactive precursor incorporation, fixation in buffered 3% glutaraldehyde, postfixation in buffered 2% OsO₄, alcoholic dehydration, and infiltration with an epoxy resin. Detachment of these plants from the plastic surface occurred only at the final step of infiltration with pure, unpolymerized resin. After detachment, the prothalli were kept in the resin to complete infiltration and then embedded. Sections 1-2 μm thick were cut, floated on a drop of glass-distilled water on clean slides and dried at 70 C. Kodak NTB-2 liquid emulsion was applied to the mounted sections and the emulsion-coated slides stored and developed according to established methods. The resulting autoradiographs showed excellent visualization of reduced silver grains, low background levels, and good preservation of cell structure.     

The Growth Forms of Developing Fern Gametophytes: a Theoretical Consideration of Form and Function Relationships

This paper examines the hypothesis that the primary physiologicalroles of the different structures of fern gametophytes haveacted as significant evolutionary constraints on the growthforms of these structures. Geometric models of absorptive andphotoreceptive structures were constructed to describe the spherical,tip-growing, and planar growth forms, which are actually orcould hypothetically be adopted by each gametophytic structure.The surface-to-volume ratios calculated for the different absorptivestructures suggest that the tip-growing form of the fern rhizoidprovides the most favorable geometric circumstance for waterand nutrient absorption; thus, the selection pressure to optimizeabsorptive processes has apparently influenced the growth formof the absorptive structure. In contrast, similar calculationsfor photoreceptive structures demonstrate that these forms havealmost identical surface-to-volume relationships; thus, thepresumptive need to increase photoreceptive efficiency has notacted as a selection pressure for a specific photoreceptiveform. This result is interpreted in terms of how different growthforms may offer specific advantages for accomplishing otheraspects of the photosynthetic process, e.g. phototropic growthand assimilate transport, which are unrelated to photoreceptionper se. Fern gametophyte, photoreception, absorption, optimal shape, spore, protonema, prothallus     

Photosynthetic Rates of Sporophytes and Gametophytes of the Fern, Todea barbara

The photosynthetic rates of intact sporophytes or gametophytes of the fern Todea barbara grown in sterile culture were measured using an infrared gas analyzer. Sporophytes consisted of single whole plants with roots and leaves grown in tubes of agar. Gametophytes were grown as several plants covering the surface of the agar. Sporophytes had photosynthetic rates at light saturation of 8.50 microliters CO₂ per hour per milligram dry weight and 1,300 microliters CO₂ per hour per milligram chlorophyll, whereas rates for gametophytes were lower, 2.36 microliters CO₂ per hour per milligram dry weight and 236 microliters CO₂ per hour per milligram chlorophyll.     

蕨类植物配子体育及其性器官分化的研究进展

作者概述了蕨类植物生活周期中不同发育阶段的特点,并着重介绍了不,植物生长调节物质,水和温度等因素对蕨类植物配子体发育的影响以及精子囊素,光,钙离子和其它植物生长调节物质在性器官形成和分化过程中的作用,同时作者对蕨类植物性器官分化的不稳定性进行了探讨,并结合目前蕨类植物性器官分化的遗传学和分子生物学研究的最新进展,说明蕨类植物作为研究系统在植物生物学研究领域中的优势。     

蕨类植物配子体发育及其性器官分化的研究进展

作者概述了蕨类植物生活周期中不同发育阶段的特点,并着重介绍了光、植物生长调节物质、水和温度等因素对蕨类植物配子体发育的影响以及成精子囊素、光、钙离子和其它植物生长调节物质在性器官形成和分化过程中的作用。同时作者对蕨类植物性器官分化的不稳定性进行了探讨、并结合目前蕨类植物性器官分化的遗传学和分子生物学研究的最新进展,说明蕨类植物作为研究系统在植物生物学研究领域中的优势。     

Regulation of Protein Synthesis during Photomorphogenesis of Gametophytes of the Fern Onoclea sensibilis

Gametophytes of the fern Onoclea sensibilis grow as filaments in the dark and in red light and become planar in blue light. Pulse-labeling 4-day-old gametophytes with [³⁵S]methionine at different times after transfer to dark, red, and blue light environments revealed higher rates of amino acid uptake and protein synthesis in blue light than in red light or in the dark. Characterization of the extant and newly synthesized soluble proteins by one- and two-dimensional gel electrophoresis showed that the patterns of protein accumulation and synthesis in gametophytes exposed to short periods of red or blue light were qualitatively indistinguishable from those of gametophytes maintained in the dark. However, some striking increases and decreases in the levels of certain polypeptides were noted and these changes were accentuated during continued growth of gametophytes in the different environments. The results show that photomorphogenesis of gametophytes of O. sensibilis is associated with quantitative rather than qualitative changes in the population of mRNAs available for translation.     

A Role for Purines and Pyrimidines of Ribonucleic Acid in the Induction of Two-dimensional Growth in the Gametophytes of the Fern, Asplenium nidus

The inhibition of two-dimensional growth in the gametophytesof Asplenium nidus induced by purine and pyrimidine analoguesand the reversal of inhibition by natural purine and pyrimidinebases and their derivatives have been studied. Adenine and guanineand their ribosides and ribotides were more effective than cytosine,uracil, thymine, and their derivatives in preventing the inhibitiondue to 8-azaadenine and 8-azaguanine. Likewise, the inhibitoryeffects of 2-thiocytosine, 2-thiouracil,6-azauracil, and 5-fluorouracilwere overcome by the pyrimidines and their derivatives, butnot usually by the purines.Combinations of two purine analoguesor two pyrimidine analogues or one purine analogue and one pyrimidineanalogue inhibited growth more effectively than single compounds.The combined inhibitions were maximally reversed when both naturalbases or their derivatives were added to the medium. It is concludedthat there is a requirement for both purines and pyrimidinesof ribonucleic acid in the induction of two-dimensional growthin the gametophytes of Asplenium nidus.     

扇叶铁线蕨配子体发育及卵发生的显微观察

采用显微观察技术对扇叶铁线蕨配子体发育和卵发生进行了研究.结果显示:(1)扇叶铁线蕨孢子黄褐色,四面体形,具三裂缝,孢子接种后4～7 d萌发,经丝状体和片状体阶段发育为心形的原叶体,成熟原叶体雌雄同株,在原叶体基部产生精子器,在原叶体生长点下方产生颈卵器.(2)切片观察表明,扇叶铁线蕨颈卵器产生于生长点下方的表面细胞(颈卵器原始细胞),该细胞经2次分裂形成3层细胞,其上层细胞发育为颈卵器颈部壁细胞,中间细胞为初生细胞,它经2次不等分裂产生3个细胞--卵细胞、腹沟细胞和颈沟细胞;刚产生时, 3个细胞紧贴颈卵器壁,随着发育,卵细胞和腹沟细胞之间产生了分离腔,同时在卵细胞上表面形成了染色深的卵膜;此后,颈沟细胞和腹沟细胞逐渐退化,在颈沟内产生大量不定形物质,受精作用观察表明,该物质能够吸引精子进入颈卵器.(3)连续切片观察发现,成熟卵细胞上表面卵膜中央具有受精孔,表明受精孔在同型孢子蕨类卵细胞中可能是普遍存在的.     

乌蕨配子体发育及卵发生的显微观察

采用光学显微镜对乌蕨的配子体发育及卵发生的过程进行了研究,以阐明蕨类植物颈卵器发育特征,为揭示蕨类植物有性生殖机制以及鳞始蕨科的演化提供依据。结果表明:(1)乌蕨孢子黄褐色,具单裂缝,表面平滑或呈疣状纹饰;孢子接种12d萌发,萌发类型为书带蕨型,原叶体发育类型为铁线蕨型。(2)半薄切片观察表明,乌蕨颈卵器产生于原叶体生长点下方的表面细胞,即颈卵器原始细胞,该细胞经过两次分裂形成纵向3层细胞,最上层细胞发育为颈卵器的颈部壁细胞,中间层细胞即初生细胞再经过两次不等分裂产生颈沟细胞、腹沟细胞和卵细胞,此三细胞最初紧密贴合,随着颈卵器的发育,卵细胞与腹沟细胞间从两侧向中间产生分离腔,且腹沟细胞与颈沟细胞开始退化;分离腔逐渐向中间扩大,直至出现孔状结构,即受精孔;颈卵器发育后期,在卵细胞上表面形成染色较深的卵膜,颈沟细胞与腹沟细胞退化成絮状物。     

蕨配子体发育及卵发生的显微结构观察

运用显微观察技术对蕨(Pteridium aquilinum var. latiusculum)配子体发育和卵发生进行了研究。结果表明：(1)蕨孢子黄褐色,四面体形,具三裂缝,接种后3～7 d萌发,经丝状体和片状体阶段发育成原叶体,成熟原叶体雌雄异株或同株。(2)蕨颈卵器产生于生长点下方的表面细胞(颈卵器原始细胞),该细胞经2次分裂形成3层细胞,其上层和下层细胞发育为颈卵器壁细胞,中间细胞为初生细胞,它经2次不等分裂产生3个细胞,分别为卵细胞、腹沟细胞和颈沟细胞;刚产生时,此3个细胞紧贴颈卵器壁,细胞质内液泡较多,随着发育,卵细胞和腹沟细胞之间产生了分离腔,但二者通过孔区相连,在卵细胞上表面可观察到卵膜;此后,颈沟细胞和腹沟细胞逐渐退化,颈卵器壁细胞内具有黑色颗粒物质。连续切片观察发现,成熟卵细胞上表面中央具有受精孔。卵发生的细节尚需超微结构的研究。     

Studies on Growth Inhibition of Hiochi-bacteria,Specific Saprophytes of Sake

A new growth inhibitant against hiochi-bacteria, C₁₁H₁₈N₂O, m.p. 173~4°C, named muta-aspergillic acid, has been isolated from the crystals of crude hydroxyaspergillic acid, obtained from culture filtrate of Asp. oryzae. Successful separation of these two compounds from each other was accomplished by counter current distribution method. The physical and chemical properties of muta-aspergillic acid as well as its physiological properties are described.     

Studies on Growth Inhibition of Hiochi-bacteria,Specific Saprophytes of Sake

The outline of this report has already been published as a short communication concerning muta-aspergillic acid, C₁₁H₁₈N₂O₃, a new growth inhibitant against hiochi-bacteria. Deoxymuta-aspergilhc acid, C₁₁H₁₃N₂O, reduction product of muta-aspergillic acid, was converted to 2,5-diketopiperazine, C₁₁H₂₀N₂O₂, and this compound was shown to be leucyl-valine anhydride since on hydrolysis, it yielded leucine and valine. These results and physical and chemical data on muta-aspergillic acid led to draw the conclusion that formula (I) or (II) is the most possible structure for this antibiotic.     

Linkage Mapping of DNA Markers Generated with Specific and Non-Specific Gene Primers in Soybean

Polymerase chain reaction (PCR) has been used extensively in the construction of linkage maps for many cultivated crops including soybean, [Glycine max (L.) Merr]. In this study, four sets of oligonucleotide primer pairs of known genes (pearl millet Adh 1, nodule specific proline-rich protein, Drosophila homeobox, heat shock protein), several different combinations from kits A, D, E, and J of arbitrary primers and five primer pairs of soybean simple sequence repeats of varying length (Satt 9, Satt 20, Satt 42, Satt 64, and Satt 30) were utilized in PCR to identify molecular markers which were then used to construct a genetic linkage map. DNA for the PCR reactions was isolated from 65 recombinant inbred soybean lines resulting from crossing PI 290,136 and BARC-2 (Rj ₄ ), followed by self-pollination for seven generations without selection. Mapmaker 3.0, a computer package, was used for construction of the linkage map. A total of 43 polymorphic markers were identified; 30 markers were linked and distributed among 5 linkage groups while 13 markers were unlinked. Arbitrary primers revealed more polymorphisms than specific primers. A combination of arbitrary primers A5 and A18 revealed the maximum number of polymorphic bands. Five observed linkage groups can be expanded in future soybean research by using additional markers.     

Effects of Colchicine and Light on Cell Form in Fern Gametophytes. Implications for a Mechanism of Light-induced Cell Elongation

Spores of the fern, Onoclea sensihilis L., suffer a disruption of normal development when they are cultured on media containing colchicine. Cell division is inhibited, and the spores develop into giant spherical cells under continuous white fluorescent light. In darkness only slight cell expansion occurs. Spherical cell expansion in the light requires continuous irradiation. Photosynthesis does not seem to be involved, since variations in light intensity do not affect the final cell diameter; the addition of sucrose to the medium does not permit cell expansion in darkness; and the inhibitor DCMU does not block the light-induced cell expansion. Continuous irradiation of colchicine-treated spores with blue, red or far-red light produces different patterns of cell expansion. Blue light permits spherical growth, similar to that found under white light, whereas red and far-red light promote the reestablishment of polarized filamentous growth. Although ethylene is unable to induce polarized cell expansion in colchicine-treated spores in darkness or white and blue light, it enhances filamentous growth which already is established by red or far-red irradiation. Both red and far-red light increase the elongation of normal filaments (untreated with colchicine) above that of dark-grown plants, but under all 3 conditions the rates of volume growth are identical. Light, however, does cause a decrease in the cell diameters of irradiated filaments. These data are used to construct an hypothesis to explain the promotion of cell elongation in fern protonemata by red and far-red light. The model proposes light-mediated changes in microtubular orientation and cell wall structure which lead to restriction of lateral cell expansion and enhanced elongation growth.     

Variability in Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase Small Subunits and Carboxylation Activity in Fern Gametophytes Grown under Different Light Spectra

Two distinct ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) small subunit (SSU) populations were observed in Pteris vittata gametophytes grown under different illumination conditions. Exposure of the fern gametophytes to continuous red light (R) resulted in Rubisco SSUs that were not recognized by polyclonal antibodies raised against SSUs from spinach. Unlike the R-induced SSUs, blue light (B) induced SSUs were well recognized. This difference in SSU composition also reflected in Rubisco activity. In vitro, B-induced Rubisco exhibits a significantly higher carboxylation activity as compared to the R-induced Rubisco. Approximately a two- to threefold increase in the V_max value of the B-induced carboxylase as compared to the R-induced one was measured. It thus seems very likely that certain domains in the SSU molecule affect enzyme activity.