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121.
The differentiation of glial cells and glia limitans in organ cultures of chick spinal cord 总被引:1,自引:0,他引:1
Summary Differentiation of glial cells and the glia limitans in organ cultures of chick spinal cord explanted at early neural tube
stages, alone or with adjacent tissues, was studied by electron microscopy. Oligodendrocytes and astrocytes comparable to
those seen in the chicken in vivo were observed, mainly in areas of good neuronal differentiation. A glia limitans with basal
lamina, comparable to that in vivo, was found when spinal cord was bordered by normally adjacent tissues. When it was surrounded
by vitelline membrane only, a characteristic limiting layer of glial processes, but no basal lamina, was seen. Contact with
a filter membrane (Millipore) elicited excessive differentiation of glial filaments and modified cell fine structure; no glia
limitans was formed.
Supported by Grant 5 RO 1 NB 0637 from the United States Public Health Service. 相似文献
122.
In grass, the evolutionary relationship between lemma and palea, and their relationship to the flower organs in dicots have been variously interpreted and wildely debated. In the present study, we carried out morphological and genetic analysis of a palealess mutant (pal) from rice (Oryza sativa L.), and fine mapping the gene responsible for the mutated trait. Together, our findings indicate that the palea is replaced by two leaf-like structures in the pal flowers, and this trait is controlled by one recessive gene, termed palealess1 (pal1). With a large F2 segregating population, the pal1 gene was finally mapped into a physical region of 35 kb. Our results also suggest that the lemma and palea of rice are not homologous organs, palea is likely evolutionarily equivalent to the eudicot sepal, and the pal1 should be an A function gene for rice floral organ identity. 相似文献
123.
Lucie Sancey Vincent Motto-Ros Shady Kotb Xiaochun Wang Fran?ois Lux Gérard Panczer Jin Yu Olivier Tillement 《Journal of visualized experiments : JoVE》2014,(88)
Emission spectroscopy of laser-induced plasma was applied to elemental analysis of biological samples. Laser-induced breakdown spectroscopy (LIBS) performed on thin sections of rodent tissues: kidneys and tumor, allows the detection of inorganic elements such as (i) Na, Ca, Cu, Mg, P, and Fe, naturally present in the body and (ii) Si and Gd, detected after the injection of gadolinium-based nanoparticles. The animals were euthanized 1 to 24 hr after intravenous injection of particles. A two-dimensional scan of the sample, performed using a motorized micrometric 3D-stage, allowed the infrared laser beam exploring the surface with a lateral resolution less than 100 μm. Quantitative chemical images of Gd element inside the organ were obtained with sub-mM sensitivity. LIBS offers a simple and robust method to study the distribution of inorganic materials without any specific labeling. Moreover, the compatibility of the setup with standard optical microscopy emphasizes its potential to provide multiple images of the same biological tissue with different types of response: elemental, molecular, or cellular. 相似文献
124.
Analysis of the S-locus structure in Prunus armeniaca L. Identification of S-haplotype specific S-RNase and F-box genes 总被引:3,自引:0,他引:3
Romero C Vilanova S Burgos L Martínez-Calvo J Vicente M Llácer G Badenes ML 《Plant molecular biology》2004,56(1):145-157
The gametophytic self-incompatibility (GSI) system in Rosaceae has been proposed to be controlled by two genes located in the S-locusan S-RNase and a recently described pollen expressed S-haplotype specific F-box gene (SFB). However, in apricot (Prunus armeniaca L.) these genes had not been identified yet. We have sequenced 21kb in total of the S-locus region in 3 different apricot S-haplotypes. These fragments contain genes homologous to the S-RNase and F-box genes found in other Prunusspecies, preserving their basic gene structure features and defined amino acid domains. The physical distance between the F-boxand the S-RNase genes was determined exactly in the S
2-haplotype (2.9kb) and inferred approximately in the S
1-haplotype (< 49kb) confirming that these genes are linked. Sequence analysis of the 5 flanking regions indicates the presence of a conserved region upstream of the putative TATA box in the S-RNase gene. The three identified S-RNase alleles (S
1, S
2 and S
4) had a high allelic sequence diversity (75.3 amino acid identity), and the apricot F-box allelic variants (SFB1, SFB2 and SFB4) were also highly haplotype-specific (79.4 amino acid identity). Organ specific-expression was also studied, revealing that S
1- and S
2-RNases are expressed in style tissues, but not in pollen or leaves. In contrast, SFB
1 and SFB
2 are only expressed in pollen, but not in styles or leaves. Taken together, these results support these genes as candidates for the pistil and pollen S-determinants of GSI in apricot. 相似文献
125.
126.
CRBP-III:lacZ expression pattern reveals a novel heterogeneity of vascular endothelial cells 总被引:1,自引:0,他引:1
Vascular endothelial cells are structurally and functionally heterogeneous. However, the molecular basis of this heterogeneity remains poorly defined. We used subtractive and differential screening to identify genes that exhibit heterogeneous expression patterns among vascular endothelial cells. One such gene is cellular retinol binding protein III (CRBP-III/Rbp7). Analysis of the lacZ knockin line for this gene (CRBP-III:lacZ) revealed a novel organ-specific vascular endothelial expression pattern. LacZ was expressed in vascular endothelial cells in heart, skeletal muscle, adipose tissues, thymus, and salivary gland. However, it was not detected in other tissues such as brain, liver, and lung. Furthermore, the expression within each organ was primarily restricted to small capillary endothelial cells, but could not be detected in larger vessels. This organ-specific vascular endothelial expression of CRPB:lacZ is relatively resistant to the changes of organ microenvironment. However, the level of expression can be modified by vitamin A deficiency. Therefore, our results provide novel molecular evidence for the heterogeneity of vascular endothelial cells. 相似文献
127.
Auxin: A major regulator of organogenesis 总被引:2,自引:0,他引:2
Isabelle Bohn-Courseau 《Comptes rendus biologies》2010,333(4):290-296
Plant development is characterized by the continuous initiation of tissues and organs. The meristems, which are small stem cell populations, are involved in this process. The shoot apical meristem produces lateral organs at its flanks and generates the growing stem. These lateral organs are arranged in a stereotyped pattern called phyllotaxis. Organ initiation in the peripheral zone of the meristem involves accumulation of the plant hormone auxin. Auxin is transported in a polar way by influx and efflux carriers located at cell membranes. Polar localization of the PIN1 efflux carrier in meristematic cells generates auxin concentration gradients and PIN1 localization depends, in turn, on auxin gradients: this feedback loop generates a dynamic auxin distribution which controls phyllotaxis. Furthermore, PIN-dependent local auxin gradients represent a common module for organ initiation, in the shoot and in the root. 相似文献
128.
129.
In common with most Old World Gesneriaceae; Streptocarpus Lindl. shows anisocotylous growth, i.e., the continuous growth of one cotyledon after germination. Linked to this phenomenon
is an unorthodox behaviour of the shoot apical meristem (SAM) that determines the growth pattern of acaulescent species (subgenus
Streptocarpus). In contrast caulescent species develop a conventional central post-embryonic SAM (mainly subgenus Streptocarpella). We used S. rexii Lindl. as a model to investigate anisocotyly and meristem initiation in Streptocarpus by using histological techniques and analyses of the expression pattern of the meristematic marker SrSTM1 during ontogeny. In contrast to Arabidopsis thaliana (L.) Heynh., S. rexii does not establish a SAM during embryogenesis, and the first evidence of a SAM-like structure occurs during post-embryonic
development on the axis (the petiolode) between the two cotyledons. The expression pattern of SrSTM1 suggests a function in maintaining cell division activity in the cotyledons before becoming localized in the basal meristem,
initially at the proximal ends of both cotyledons, later at the base of the continuously growing macrocotyledon, and the groove
meristem on the petiolode. The latter is equivalent to a displaced SAM seemingly originating de novo under the influence of
endogenous factors. Applied cytokinin retains SrSTM1expression in the small cotyledon, thus promoting isocotyly and re-establishment of a central post-embryonic SAM. Hormone-dependent
delocalization of the process of meristem development could underlie anisocotyly and the unorthodox SAM formation in Streptocarpus.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
130.
Homeobox genes are essential regulators of plant development. ATHB23, a class I homeodomain leucine zipper gene of Arabidopsis, was found to be induced by treatment with the phytohormone gibberellin (GA). In order to clarify its role in development, we performed a histochemical analysis of transgenic plants containing a construct with a GUS::GFP reporter under the control of the 1.5 kb upstream region of ATHB23. The construct was mainly expressed in young leaves and the styles of flowers but not in mature leaves. Microscopic examination of young leaves revealed that it was expressed in the adaxial domain of leaf primordia and the rib meristem. Expression of ATHB23, like that of GA5 encoding GA 20-oxidase, was reduced in mutants related to adaxial-abaxial leaf polarity (phb-1d, se-2, and kan1 kan2). Reduced expression of the GUS::GFP reporter gene was also observed in an se-2 background. These results indicate that ATHB23 is under the control of GA and other activators such as PHB, and is involved in establishing polarity during leaf development. 相似文献