The Somatic Function of the Germ Nucleus in Pseudourostyla cris tat a: Asexual Reproduction and Stomatogenesis

The micronuclei of the ciliated protozoan Pseudourostyla cristata were eliminated by amputation shortly before binary fusion. The amicronucleate cell lines derived from regenerants were maintained for more than a year. They exhibited a lower viability and reduced vigor in asexual propagation. There was some improvement in the growth of the cell lines 1 mo after operation, but the growth rate remained subnormal even up to 1 yr of culture. The exact cause of the poor growth and survival in the first 3 wk after operation, whether the loss of the micronucleus or operational damage, remains to be determined. It is nevertheless clear that the micronucleus is important for subsequent asexual propagation. The amicronucleate cell lines were permanently crippled in morphogenesis, unlike the situation in Paramecium amicronucleates in which stomatogenesis returned to near-normal during asexual propagation. They always included some cells with a characteristically defective adoral zone of membranelles, reduced number of frontal-ventral-transverse cirri, and reduced body length. They were also reluctant to encyst. It is evident that the micronucleus is important for maintaining normality of the oral apparatus. It is postulated that the permanent stomatogenic crippling of amicronucleates might be related to genomic reduction in the developing macronucleus in sexual reproduction, as exhibited by other hypotrichs. The morphological defects associated with the adoral zone of membranelles may be rationalized as arising from the spreading of a zone of degeneration in the cortex affecting the left edge of the membranelles.     

Doublet Formation and Cytoplasmic Symbionts in the Ciliate Urostyla grandis

The formation of homopolar doublets can be induced by the action of antibiotics which inhibit the growth of cytoplasmic bacterial symbionts whose cell cycle appears to be controlled by the host. They multiply during the macronuclear S-phase of the ciliate and become enclosed in vesicles and are largely destroyed just before cell division is completed. Since doublet formation is due to an incomplete cell division, and because experimental disturbances at the cell cortex of dividing ciliates also lead to doublets, the symbionts are thought to contribute some factor which is essential for normal cytokinesis of the host cell.     

Structure of Protein Bodies and Elemental Composition of Phytin from Dry Germ of Maize (Zea mays L.)

Protein bodies (PBs) from the epidermis and cortex of the radicle, as well as from coleorhizal and scutellar parenchyma of dry maize seeds were studied with the emphasis on presence and elemental composition of globoid crystals. PBs with variable structure were found in investigated tissues. Radicular epidermis was the only investigated tissue containing structurally uniform populations of PBs. They were filled by a homogeneous matrix without globoid crystals or their remnants. PBs structure and amount of proteinaceous matrix varied in the same cell of coleorhiza and scutellum. In the case of radicular cortex, the structure of PBs differed between analyzed individuals. Globoid crystals of various sizes were found in PBs from scutellum, coleorhiza, and from inner layers of radicular cortex. The largest globoid crystals (up to 2.0 μ in diameter) were seen in the scutellum. Energy-dispersive X-ray microanalysis revealed the presence of P,K. Mg, and some traces of Fe and Zn in the majority of globoid crystals from the scutellum. Globoid crystals from coleorhiza and radicular cortex were rich in Zn and Ca. The presence of considerable Zn was usually accompanied by high Ca, at the expense of K and Mg. As EDX analyses revealed significant differences in Zn and Zn/P values between analyzed tissues, it is probable that the majority of Zn is preferably accumulated in globoid crystals of some tissues of maize germ.     

七叶一枝花根的显微结构及其内生真菌分布研究

本文采用石蜡永久制片和光学显微摄像的方法对七叶一枝花Parispolyphylla根的显微结构及其内生真菌的分布进行了研究。结果表明,七叶一枝花的根茎由栓皮层、薄壁组织及维管组织组成,其中栓皮层由4层细胞组成;薄壁组织的细胞含有丰富的营养物质,其内有时分布有针状结晶束。不定根由表皮层、皮层、内皮层及维管束构成,表皮上有根毛,皮层所占根径的比例达80%以上;木质部为三原型。在七叶一枝花的根茎和不定根的皮层细胞中均有内生真菌的分布。真菌由表皮、外皮层侵入到皮层薄壁组织,在皮层薄壁细胞中形成菌丝结,并扩展成一定的侵染区域,部分皮层细胞中菌丝结已被消化吸收。内生真菌只侵染皮层薄壁细胞,不侵染维管柱。七叶一枝花可以通过消化细胞内的菌丝作为营养的来源之一。     

牡丹愈伤组织发生和分生结节形成的细胞组织学研究

以牡丹‘Golden era’叶柄薄层为外植体,结合外部形态,对愈伤组织发生,并分化为分生结节过程进行了细胞组织学研究,为进一步研究牡丹不定器官分化、实现离体微繁殖奠定基础。结果表明:愈伤组织的发生与发育经历了启动、分裂、形成和组织分化4个时期。启动期,外植体束中形成层最先去分化,表现为形态上变暗,内部细胞核变大,淀粉代谢增强。细胞旺盛增殖的分裂期,先后于外植体形成层和皮层薄壁细胞处产生了愈伤组织,形成了质地紧实的愈伤增殖团,愈伤细胞体积小、质浓、核位于中心,且具有绕核积累的淀粉粒。形成期,愈伤组织增殖速度减缓,只有接触培养基的周缘愈伤组织仍在增殖。组织分化期,愈伤组织内部分化出维管单元,可以作为生长中心,有的是以特化的薄壁细胞为生长中心,外围核大、质浓的薄壁细胞层形成了具有再生潜能的分生结节。     

The Homoscleromorph sponge Oscarella lobularis,a promising sponge model in evolutionary and developmental biology

Sponges branch basally in the metazoan phylogenetic tree and are believed to be composed of four distinct lineages with still uncertain relationships. Indeed, some molecular studies propose that Homoscleromorpha may be a fourth Sponge lineage, distinct from Demospongiae in which they were traditionally classified. They harbour many features that distinguish them from other sponges and are more evocative of those of the eumetazoans. They are notably the only sponges to possess a basement membrane with collagen IV and specialized cell‐junctions, thus possessing true epithelia. Among Homoscleromorphs, we have chosen Oscarella lobularis as a model species. This common and easily accessible sponge is characterized by relatively simple histology and cell composition, absence of skeleton, and strongly pronounced epithelial structure. In this review, we explore the specific features that make O. lobularis a promising homoscleromorph sponge model for evolutionary and developmental researches.     

Common tree shrews and primates share leukocyte membrane antigens

Monoclonal antibodies reactive with human peripheral blood lymphocyte and myeloid cell surface antigens were utilized to study the phylogeny of the common tree shrew. Blood cells from the common tree shrew, but not the bat or short-tailed shrew, react with certain of these antibodies. These data strengthen the argument that the Tupaiidae are primitive primates rather than insectivores. They also indicate that this approach should be useful for further work in taxonomic systemization.     

Cell lineage tree models of neurogenesis

The production of neurons to form the mammalian cortex, known as embryonic cortical neurogenesis, is a complex developmental process. Insight into the process of cell division during neurogenesis is provided by murine cortical cell lineage trees, recorded through experimental observation. Recurring patterns within cell lineage trees may be indicative of predetermined cell behaviour. The application of mathematical modelling to this process requires careful consideration and identification of the key features to be incorporated into the model. A biologically plausible stochastic model of evolution of cell lineage trees is developed, based on the most important known features of neurogenesis. Tractable means of measuring lineage tree shape are discussed. Symmetry is identified as a significant feature of shape and is measured using Colless's Index of Imbalance. Distributions of tree size and imbalance for large tree sizes are computed and results compared to experimental data. Several refinements to the model are investigated, when the cell division probabilities are weighted according to cell generation. Two models involving generation-dependent cell division probabilities produce imbalance distributions which are the most consistent with the available experimental results. The results indicate that a stochastic cell division mechanism is a plausible basis of mammalian neurogenesis.     

树类-细小病毒的初步研究

从树肾细胞培养物中分离出3株病毒,嗜在对数分裂期的TL细胞上复制,产生细胞病变和血凝素抗原,能凝集豚鼠和小鼠红细胞。交互血凝抑制实验表明3株病毒同属一个血清型。免疫酶染色显示抗原首先出现于细胞核。电镜观察负染标本病毒形态近似圆形和六角形,无胞膜,直径约30nm。血清学检查大多数树血清中含有该病毒抗体,证明是树的一种潜在病毒。初步鉴定为类细小病毒。     

减压、低温条件下制样的几种植物液泡图象

样品制作中选用的固定剂不同,在电子显微镜下所得的图象差异甚大。高锰酸钾固定的样品中(Luft 1956,Mollenhauer1959),液泡是一个空泡,核也是一个空泡。用四氧化锇(Palade 1952)和醛类-四氧化锇双固定的样品(Sabatini等1963)核内有物质,但液泡仍是一空泡。所有电子显微技术样品制作都离不开固定、脱水、包埋等过程中化学试剂的反复处理,化学试剂处理细胞会抽去部分细胞内含物;或与细胞某些内含物结合形成络合物。从而     

RADIOAUTOGRAPHIC STUDIES OF THE STEM CELL IN THE THYMUS OF THE IRRADIATED RAT

Radioautographic evidence is presented which characterizes the marrow derived stem cell which promotes thymic recovery following irradiation in the rat. These immigrant cells are similar in morphology to blood monocytes and have been called monocytoid, meaning monocyte-like in appearance. The typical cell had abundant pale staining cytoplasm and a nucleus with many invaginations and folds and a fine chromatin structure. There was no prominent nucleolus. The majority of these cells entered the thymus of the irradiated rat via the blood vessels into the septa and made their way through the connective tissue to the outer cortex. Three distinct morphological cell types appeared to be derived from the immigrant cells. These were fibrocyte-like cells which were located within the septa, macrophages located mainly within the medulla and septa, and large blast cells within the cortex, which proliferated giving rise to large thymocytes. The blast cells were characterized as having abundant moderately basophilic (and pyroninophilic) cytoplasm with a distinct cytoplasmic boundary, a large nucleus which still had invaginations and folds, a loose chromatin structure and one or more very prominent nucleoli. They were located in groups primarily within the outer cortex and often adjacent to blood vessels. They were found to be highly susceptible to damage in smear preparations. In contrast, their progeny, the large thymocytes were not highly susceptible to damage in smear preparations but teased out as large round cells with a highly basophilic rim of cytoplasm. The large thymocytes were precursors to medium and small cells. A radioautographic technique for 1 μ tissue sections is also described.     

Collagen formation by fibroblasts of the chick embryo dermis

This investigation has sought to determine the relation between collagen fiber and fibroblast during fibrogenesis. Toward this end the surfaces of chick fibroblasts grown under in vitro conditions have been examined with the electron microscope after fixation in OsO(4). Supplementary information has been obtained from thin sections of fibroblasts fixed in situ during phases of fiber production. The evidence provided by these studies and by various conditions of the experiments indicates that the unit fibrils of collagen form in close association with the cell surface. They were never observed within the cell. When these unit fibrils form in bundles it appears as though templates of some nature, possibly coinciding with stress fibers within the cell cortex, influence the polymerization of the fibrils out of material available at the cell surface. From here the fibrils and bundles of them are shed into the intercellular spaces and there grow to limited diameters by accretion of materials from the general milieu.     

黄河三角洲滨海盐碱地11个造林树种细根解剖性状对土壤条件的响应

细根作为植物与土壤连接的重要部位,能够反映植物对生存环境的适应性。以黄河三角洲滨海盐碱地不同立地条件下11个造林树种为对象,基于细根分支等级划分1-4级根序并进行解剖特征测定,分析细根解剖性状对滨海盐碱地不同土壤条件的响应规律。结果表明：（1）不同根序的细根直径存在显著差异,细根直径随根序升高呈增大趋势,而同根序的细根直径在不同树种间表现出显著的种间差异（P < 0.05）。1-2级细根皮层厚度、3-4级细根导管密度在树种间的差异均达显著水平（P < 0.05）。（2）在较为严重盐渍化土壤条件下（立地1）,细根皮层厚度较其他立地显著增大,但细根导管密度较小;在轻度盐碱立地条件下（立地3）,细根导管密度较大;较为严重的盐碱立地具有更为发达的细根直径及维管柱直径。（3）树种1-2级细根解剖结构与土壤环境关系最为密切,其中1级根直径与土壤pH值显著正相关（P < 0.05）,与土壤硝态氮含量呈显著负相关（P < 0.05）。对土壤理化性质与细根解剖性状的冗余分析表明,前两个轴的特征值达0.640和0.196,土壤速效养分含量与轴一（RDA1）呈正相关,低级根解剖性状则与轴二（RDA2）呈显著负相关。低级根解剖结构以及土壤的pH值能解释较多树种的差异性,其中低级根直径与皮层厚度对盐碱环境表现出较强的响应。     

中国现生六种非人灵长类和树鼩大脑两半球不对称性的比较研究

对中国现生六种灵长类动物：懒猴、猕猴、灰叶猴、川金丝猴、滇金丝猴、长臂猿以及与灵长类关系密切的树鼩的大脑两半球形态,功能的不对称性以及由此引起的行为不对称性进行了研究。结果表明：大脑两半球不对称现象均存在于上述几种动物中。因而,这种不对称性可能经历了一个长期演化历程。     

Variation in wood anatomical traits of Pinus sylvestris L. between Spanish regions of provenance

The Spanish populations of Pinus sylvestris L. occupy differentiated sites and must therefore include structural variations to cope with varied climate conditions. This study compares wood anatomical traits of P. sylvestris from ten Spanish regions of provenance with contrasting climates, taking into account the effects of region of provenance and tree nested within provenance on variation in wood biometry. In general, the effect of both sources of variation (provenance and tree) on wood biometry was highly significant. Most of the anatomical variations observed were intra-populational (at the tree level), although variation explained by provenance was high for some parameters (e.g., ray frequency and ray parenchyma cell frequency), suggesting high environmental influence. Trees in the driest region, growing in a Mediterranean phytoclimate, were characterized by large tracheid lumens, suggesting more efficient water conduction. They also had thick cell walls, which would reduce the risk of cavitation caused by high implosion stress during periods of drought, as well as a high ray tracheid frequency, implying greater water storage capacity in the sapwood. The population with greatest growth, located in an oroboreal phytoclimate, was characterized by large bordered pits and long tracheids, which would reduce resistivity in water transport. At higher altitudes, tracheid lumen diameter and resin canal diameter tended to be smaller, and intertracheid wall strength was greater. Results are discussed in relation to adaptation of the species to growth demands and frost.     

Geotaxis and phototaxis are not determinant factors for white pine weevil (Col., Curculionidae) oviposition location on intact trees and severed treetops

Abstract:  The objective of this investigation was to determine if external factors such as phototaxis and geotaxis determine oviposition site location by reproductively active female white pine weevils, Pissodes strobi (Peck), on intact trees or cut treetops. In prior studies, light and gravity, both external tree factors, were consistently linked with oviposition location. In this study, the external factors that were varied in whole trees or cut treetops, included two weevil populations and two tree species in upright, inverted and horizontal orientations with thick or thin stems, indoor and outdoor locations, warm and cool, wet and dry, and light and dark conditions. The results show that 100% of the oviposition occurred at or near treetops, regardless of external factors. The results are unequivocal; they are without variance. These findings suggest that the reproductively active female weevil's feeding preference is for primary cortex tissue, an internal tree factor. The primary cortex thickness gradient could account for these weevils' capability to locate treetops, where the thickest primary cortex tissue occurs, even when treetops are not at the highest or brightest locations.     

Collagen Formation by Fibroblasts of the Chick Embryo Dermis

This investigation has sought to determine the relation between collagen fiber and fibroblast during fibrogenesis. Toward this end the surfaces of chick fibroblasts grown under in vitro conditions have been examined with the electron microscope after fixation in OsO₄. Supplementary information has been obtained from thin sections of fibroblasts fixed in situ during phases of fiber production. The evidence provided by these studies and by various conditions of the experiments indicates that the unit fibrils of collagen form in close association with the cell surface. They were never observed within the cell. When these unit fibrils form in bundles it appears as though templates of some nature, possibly coinciding with stress fibers within the cell cortex, influence the polymerization of the fibrils out of material available at the cell surface. From here the fibrils and bundles of them are shed into the intercellular spaces and there grow to limited diameters by accretion of materials from the general milieu.     

Selective induction of tyrosine hydroxylase by cell-cell contact in bovine adrenal chromaffin cells is mimicked by plasma membranes

As a first step towards the identification and purification of the molecule(s) that are involved in cell contact-mediated tyrosine hydroxylase (TH) induction in cultures of bovine adrenal chromaffin cells, we have prepared plasma membranes (PM) from bovine adrenal medulla and tested their ability to mimick cell contact-mediated TH induction in low density chromaffin cultures. PM indeed induced TH in a manner similar to that observed in high density cultures. The maximal TH induction reached by PM corresponded to 69% of that of high density cultures, and half-maximal TH induction was obtained with 12 micrograms of PM per ml of medium. The induction of TH by PM was blocked by alpha-amanitin as observed in high density cultures. Since acetylcholinesterase was neither induced in high density nor in PM-treated low density cultures, an induction of TH as a result of a general increase in protein synthesis was excluded. The cell contact molecule(s) appear to be intrinsic membrane proteins. They were not removed by high or low salt extraction, but solubilized by 50 mM octylglucoside. They were resistant to 0.1% trypsin and heat denaturation but inactivated by 0.01% chymotrypsin. PM isolated from the adrenal cortex, kidney, and liver also induced TH in low density chromaffin cell cultures, although to a smaller extent than PM of the adrenal medulla. In contrast, muscle and erythrocyte PM were inactive. This shows that the cell contact molecule(s) are not restricted to the adrenal medulla, but are also present in some other but not all tissues.     

Somatostatin-immunoreactive senile plaque-like structures in the frontal cortex and nucleus accumbens of aged tree shrews and Japanese macaques

BACKGROUND: Previously, we demonstrated decreased expression of somatostatin mRNA in aged macaque brain, particularly in the prefrontal cortex. To investigate whether or not this age-dependent decrease in mRNA is related to morphological changes, we analyzed somatostatin cells in the cerebra of aged Japanese macaques and compared them with those in rats and tree shrews, the latter of which are closely related to primates. Methods: Brains of aged macaques, tree shrews, and rats were investigated by immunohistochemistry with special emphasis on somatostatin. Results: We observed degenerating somatostatin-immunoreactive cells in the cortices of aged macaques and tree shrews. Somatostatin-immunoreactive senile plaque-like structures were found in areas 6 and 8 and in the nucleus accumbens of macaques, as well as in the nucleus accumbens and the cortex of aged tree shrews, where amyloid accumulations were observed. CONCLUSIONS: Somatostatin degenerations may be related to amyloid accumulations and may play roles in impairments of cognitive functions during aging.     

CORTICAL ONTOGENY IN ROOTS. I. ZEA MAYS

Serial growth stages of young Zea mays primary roots were analyzed for patterns of ground meristem ontogeny. The number of cell layers in the cortex decreases from approximately 15 to 11 during early root growth. The cortex arises mostly by periclinal divisions in the outer portions of the ground meristem at levels 50–150 μm from the meristem tip, although some layers of outer cortex arise beyond 150 μm. The proendodermis contributes 3–5 cell layers to the cortex, but this contribution diminishes during early seedling growth as anticlinal divisions occur in the proendodermis. The relationship between the ground meristem and protoderm changes at the tip of the meristem during root elongation.