Effects of brain and mesenchyme upon the cytogenesis of rat adenohypophysis in vitro

Summary The objective of this in-vitro study was to examine whether the diencephalic floor or the mesenchyme is involved in differentiation of LH cells in the developing rat adenohypophysis. Overall growth of the adenohypophysial tissue was retarded when the adenohypophysial primordium was cultivated after enzymatic removal of the diencephalic floor on days 11.5 and 12.5 of gestation. This malgrowth was more marked when the brain was separated on day 11.5; most expiants retained a simple cystiform structure that consisted of a few layers of undifferentiated cells. Removal of the brain also caused a highly significant decrease (P < 0.001) in the number of immunoreactive LH cells, if it was performed on day 11.5 but not day 12.5. Mesenchyme had little effect on the adenohypophysial growth or the number of immunopositive cells. Cultivation of the adenohypophysial primordium with the diencephalic floor resulted in the appearance of many immunoreactive LH cells. The number of LH cells significantly decreased, however, when the co-cultivated brain completely surrounded the adenohypophysial tissue.These results indicate that in 11.5-day-old fetal rats the diencephalic floor is indispensable for the initial proliferation of adenohypophysial primordial cells and for the early determinating process of LH cells. Once determined, the development of LH cells may proceed without the surrounding tissues. The cytodifferentiation seems to be rather inhibited when in contact with the brain. The significance of the intimate spatial relationship between developing LH cells and the surrounding mesenchyme is also discussed.     

Developmental study onHypolepis punctata (Thunb.) Mett.

The third petiolar bud ofHypolepis punctata appears on the basiscopic lateral side of the petiole above the fairly developed first petiolar bud. This investigation clarified the fact that the third bud is formed neither by the activity of the meristem of the first bud nor by the meristem directly detached from the shoot apical meristem, but is initiated in the cells involved in the abaxial basal part of the elevated portion of the leaf primordium. Thus the third bud is of phyllogenous origin. This investigation further revealed that the cells to initiate the third bud are originally located in the abaxial side of the leaf apical cell complex like the cells to initiate the first bud, but are not incorporated into the meristem of the first. After the first, second and third petiolar buds have been initiated, they are carried up into fairly high regions on the petiolar base by the intercalary growth which occurs in the leaf base below the insertion level of the first and the second buds.     

Ultrastructural and cytochemical studies on nucleolus-like bodies in early postimplantation rat embryos

Summary This study investigates the role of the developing diencephalic floor or mesenchymal tissue in the differentiation of ACTH-producing cells.The adenohypophysial primordia of fetal rats on days 12.5 and 13.5 of gestation were treated with collagenase; some primordia were allowed to retain an association with the brain and mesenchyme, but in others the brain and/or mesenchyme were removed. These different combinations of tissues were cultured and examined by immunohistochemical techniques using antisera against pACTH and synthetic -MSH. Removal of mesenchyme alone had little effect on the development of ACTH cells as compared to primordia maintained with brain and mesenchyme. In contrast, removal of the brain with or without mesenchyme on day 12.5 resulted in a marked decrease of ACTH cells accompanied by a mal-growth of adenohypophysial tissue. Such changes were slight when the brain was separated from day 13.5 primordia. Immunoreactive -MSH cells were sparse or absent in all cases.These results suggest that in fetal rats the developing diencephalic floor is essential for differentiation of ACTH cells before day 13.5 of gestation whereas mesenchyme has no apparent effect.     

Developmental studies on the leaf and the extra-axillary bud ofHistiopteris incisa

Anatomical and developmental studies have been made ofHistiopteris incisa in order to obtain a reasonable interpretation of the so-called extra-axillary bud. Single, or rarely two extra-axillary buds arise on the lateral side of the petiolar base. The branch trace appears to depart from the basiscopic margin of the leaf trace. At the earliest stage of the leaf initiation, the leaf apical cell is cut off in one of the prismatic cells of the shoot apical meristem. The leaf apical cell, then, cuts off segments successively to form a well-defined group of derivatives. On the other hand, a well-recognized cell group called “outer neighboring cell group”,onc, is found adjacent to the abaxial boundary of the derivatives of the leaf apical cell. This group of cells does not originate directly in the mother cell of the leaf apical cell. The primordium of the extra-axillary bud is always initiated in the superficial pillar-shaped cell layer ofonc. The leaf primordium may consist of two parts, the distal part derived from the leaf apical cell and the basal part from the adjacent cells includingonc. These facts suggest that the extra-axillary bud is of foliar nature. This study was partly supported by a Grant-in-Aid for Encouragement of Young Scientists by the Ministry of Education of Japan; no. 374222 in 1978.     

Light and electron microscopical study of Nosema eurytremae

A nuclear-polyhedrosis virus (NPV) of the silkworm, Bombyx mori, which forms an icosahedral inclusion body, was transmitted to larvae of the rice stem borer, Chilo suppressalis. Serial passages of Bombyx NPV in the alternate host by injecting the supernatant of diseased hemolymph produced inclusion bodies with cuboidal and other shapes that differed from the original shape formed in Bombyx. These different shapes increased with times of passages, and after the twelfth passage, only cuboidal inclusion bodies were formed. The icosahedral inclusion bodies in B. mori and the cuboidal inclusion bodies in C. suppressalis occluded singly enveloped virions of the same size (350 × 75 nm), but the cuboidal inclusion bodies contained only a few virions and a large number of membraneous spherical structures. The formation process of the cuboidal inclusion body differed from that of the icosahedral. At first, irregularly branched inclusion bodies containing “vacant” spaces appeared in the infected nuclei. The bodies grew larger with the deposition of protein in the spaces between the branches, and this was accompanied with the occlusion of a large number of membraneous structures formed in the vicinity of the inclusion bodies, which became cuboidal in shape.     

蛹虫草原基分化的差异蛋白质组学研究

蛹虫草子实体形成及发育的蛋白分子机制尚不清楚,本研究引入SWATH非标记定量蛋白质组学技术,对蛹虫草Cordyceps militaris 905菌株的菌丝体（mycelium,My）、原基（primordium,Po）、生长期子实体（developmental fruiting body,DF）和成熟期子实体（mature fruiting body,MF）进行了比较蛋白质组学分析。经搜库比对,从蛹虫草的My、Po、DF和MF中依次鉴定蛋白1 136个、1 090个、1 018个和997个（global FDR 1%）,经维恩分析后获得C. militaris 905蛹虫草表达蛋白1 578个。在此基础上,SWATH非标记技术定量蛋白1 109个。本研究获得了蛹虫草Po期与My期、DF期与Po期、MF期与DF期的差异表达蛋白,依次为115个、352个和104个,并对菌丝体分化形成原基的差异表达蛋白进行了重点解析。GO注释结果表明,Po期与My期差异表达蛋白以有机含氮类化合物代谢为主,其中AMP（活性成分虫草素合成的中间产物）从头生物合成途径富集最为显著。约1/5的差异表达蛋白参与氧化还原反应,还原酶活性的蛋白在原基中几乎都上调表达,而氧化功能的蛋白受到抑制,表明蛹虫草原基分化可能受到氧化应激的诱导。蛋白互作网络分析结果进一步表明,氧化还原反应与核苷类物质代谢相关联,可能通过影响AMP从头生物合成途径来调控虫草素的生物合成。对蛹虫草子实体系统的蛋白质组学研究和解析有利于揭示子实体形成的蛋白分子机制,为蛹虫草的基础和栽培研究提供了理论支撑。     

Drapc1 expression during mouse embryonic development

We identified the mouse homolog of human DRAPC1 (APCDD1) gene, shown to be a target of Wnt/beta-catenin signaling pathway in cancer cell lines. Analysis of its spatiotemporal expression in mouse embryos from E7.5 to E14 showed that Drapc1 is expressed during development of the extraembryonic structures, nervous system, vascular system and inner ear. In addition, Drapc1 is expressed in the mesenchyme of several developing organs at sites of epithelio-mesenchymal interactions. Drapc1 expression was also found in the hair follicles of the adult mouse skin. Similarity of Drapc1 expression pattern to location of active beta-catenin in developing mouse embryo further suggests that mouse Drapc1 is a novel in vivo target gene of Wnt/beta-catenin signaling pathway.     

植物叶发育调控机理研究的进展

在植物的营养生长阶段,叶原基从植物地上部分顶端分生组织的周边区形成,在一系列细胞分裂和分化程序的指导下,最终发育成叶。近年来,通过遗传学和分子生物学研究已经鉴定和克隆了一批参与叶发育调控的关键基因,植物激素在叶原基的诱导和叶形态建成中也起十分重要的作用。目前这个领域的主要研究工作是鉴定调控叶发育的新基因并且解释叶调控基因之间的相互作用,同时了解基因调控和植物激素作用之间的关系。     

Gβ1 controls collective cell migration by regulating the protrusive activity of leader cells in the posterior lateral line primordium

Collective cell migration is critical for normal development, tissue repair and cancer metastasis. Migration of the posterior lateral line primordium (pLLP) generates the zebrafish sensory organs (neuromasts, NMs). This migration is promoted by the leader cells at the leading edge of the pLLP, which express the G protein-coupled chemokine receptor Cxcr4b and respond to the chemokine Cxcl12a. However, the mechanism by which Cxc112a/Cxcr4b signaling regulates pLLP migration remains unclear. Here we report that signal transduction by the heterotrimeric G protein subunit Gβ1 is essential for proper pLLP migration. Although both Gβ1 and Gβ4 are expressed in the pLLP and NMs, depletion of Gβ1 but not Gβ4 resulted in an arrest of pLLP migration. In embryos deficient for Gβ1, the pLLP cells migrated in an uncoordinated fashion and were unable to extend protrusions at the leading front, phenocopying those in embryos deficient for Cxcl12a or Cxcr4b. A transplantation assay showed that, like Cxcr4b, Gβ1 is required only in the leader cells of the pLLP. Analysis of F-actin dynamics in the pLLP revealed that whereas wild-type leader cells display extensive actin polymerization in the direction of pLLP migration, counterparts defective for Gβ1, Cxcr4b or Cxcl12a do not. Finally, synergy experiments revealed that Gβ1 and Cxcr4b interact genetically in regulating pLLP migration. Collectively, our data indicate that Gβ1 controls migration of the pLLP, likely by acting downstream of the Cxcl12a/Cxcr4b signaling. This study also provides compelling evidence for functional specificity among Gβ isoforms in vivo.