Glial but not neuronal development in the cochleo-vestibular ganglion requires Sox10.

The cochleo-vestibular ganglion contains neural crest-derived glial cells and sensory neurons that are derived from the neurogenic otic placode. Little is known about the molecular mechanisms that regulate the tightly orchestrated development of this structure. Here, we report that Sox10, a high-mobility group DNA-binding domain transcription factor that is required for the proper development of neural crest cell derivatives, is specifically expressed in post-migratory neural crest cells in the cochleo-vestibular ganglion.

A short upstream promoter region mediates transcriptional regulation of the mouse doublecortin gene in differentiating neurons.

Background: Doublecortin (Dcx), a MAP (Microtubule-Associated Protein), is transiently expressed in migrating and differentiating neurons and thereby characterizes neuronal precursors and neurogenesis in developing and adult neurogenesis. In addition, reduced Dcx expression during development has been related to appearance of brain pathologies. Here, we attempt to unveil the molecular mechanisms controlling Dcx gene expression by studying its transcriptional regulation during neuronal differentiation.

Sox10 promotes the survival of cochlear progenitors during the establishment of the organ of Corti.

Transcription factors of the SoxE family are critical players that underlie various embryological processes. However, little is known about their function during inner ear development. Here, we show that Sox10 is initially expressed throughout the otic vesicle epithelium and becomes later restricted to supporting cells as cell differentiation proceeds in the organ of Corti.

Expression patterns of miR-96, miR-182 and miR-183 in the development inner ear.

MicroRNAs (miRNAs) constitute a class of small non-coding endogenous RNAs that downregulate gene expression by binding to 3' untranslated region (UTR) of target messenger RNAs. Although they have been found to regulate developmental and physiological processes in several organs and tissues, their role in the regulation of the inner ear transcriptome remains unknown. In this report, we have performed systematic in situ hybridization to analyze the temporal and spatial distribution of three miRNAs (miR-96, mR-182, and mR-183) that are likely to arise from a single precursor RNA during the development and the maturation of the cochlea.

Hair cell progenitors: identification and regulatory genes.

Hair cell loss in higher vertebrates appears to be permanent. Progenitors that are quiescent in the organ of Corti are the best candidates for the restoration of the different cell types in the organ of Corti. However, little is known about the presence of these progenitors and their capacity to differentiate into hair cells.

New insights into peripherin expression in cochlear neurons.

Peripherin is an intermediate filament protein that is expressed in peripheral and enteric neurons. In the cochlear nervous system, peripherin expression has been extensively used as a differentiation marker by preferentially labeling the type II neuronal population at adulthood, but yet without knowing its function. Since the expression of peripherin has been associated in time with the process of axonal extension and during regeneration of nerve fibers in other systems, it was of interest to determine whether peripherin expression in cochlear neurons was a static phenotypic trait or rather prone to modifications following nerve injury.

Strategies to regenerate hair cells: identification of progenitors and critical genes.

Deafness commonly results from a lesion of the sensory cells and/or of the neurons of the auditory part of the inner ear. There are currently no treatments designed to halt or reverse the progression of hearing loss. A key goal in developing therapy for sensorineural deafness is the identification of strategies to replace lost hair cells.

Enzymic potential for fructose 6-phosphate phosphorylation by guard cells and by palisade cells in leaves of the broad bean Vicia faba L.

Guard cells and palisade cells were dissected from freeze-dried leaflets of the broad bean, Vicia faba L. Individual cell samples (6-12 ng) were assayed for ATP-dependent and pyrophosphate-dependent phosphofructokinases. The assay indicator, NADH loss, was monitored in real time in oil droplets with a computer-driven microfluorometer.

Malate content of picoliter samples of Raphanus sativus cytoplasm.

Malate, which plays many essential roles in plant metabolism, is a potent in vitro inhibitor of the cytosolic enzyme phosphoenolpyruvate carboxylase (PEPC). Because PEPC activity leads to malate biosynthesis, malate is assumed to attenuate its own synthesis in situ. To test this hypothesis, we measured directly the malate content of picoliter samples of Raphanus root-hair cytoplasm using quantitative histochemical techniques.

Effect of GA(4 + 7) on the initiation and development of the inflorescence bud of evergreen azalea.

Apical buds of evergreen azalea (Rhododendron sp.) were treated with GA(4 + 7) at different stages of development. Treatment of vegetative buds stimulated shoot growth, slightly delayed both flower initiation and development, but increased the number of flower primordia.

Elevation in the Sucrose Content of the Shoot Apical Meristem of Sinapis alba at Floral Evocation.

Nanogram tissue samples from apical meristems of Sinapis alba were assayed for sucrose, total soluble hexosyl equivalents ( identical with glucose and fructose plus hexoses from sucrose hydrolysis), and total soluble glucosyl equivalents ( identical with glucose plus glucose from sucrose hydrolysis). On dry weight basis, sucrose concentration increased by more than 50% within 10 hours after the start of either a long photoperiod or a short photoperiod displaced by 10 hours in the 24-hour cycle (;displaced short day'). (These treatments induce flower initiation) Glucose and fructose concentrations were close to zero in vegetative meristems and remained low compared to sucrose in meristems of induced plants.

Changes in adenine-nucleotide content in the apical bud of Sinapis alba L. during floral transition.

The total adenylate pool of the apical buds of vegetative plants of Sinapis alba L. continuously grown in short days fluctuates over a 24-h cycle with the minimum occurring at the end of the dark period. In the buds of plants induced to flower by a single long-day treatment, total adenylate pool increases above the control level 16 h after the start of the long day, resulting mainly from a rise in ATP and ADP contents.

Promotion of Flowering in Brassica campestris L. cv Ceres by Sucrose.

Flower initiation of the quantitative long-day plant Brassica campestris cv Ceres was earlier and at a lower final leaf number when sucrose was added to the medium in which plants were grown in sterile culture. The optimal concentration of sucrose was 40 to 80 millimolar. This flower-promoting effect of sucrose was not osmotic, as mannitol, sodium chloride, and polyethylene glycol were not effective at equal osmotic potentials.

Flowering in Xanthium strumarium: INITIATION AND DEVELOPMENT OF FEMALE INFLORESCENCE AND SEX EXPRESSION.

Vegetative plants of Xanthium strumarium L. grown in long days were induced to flower by exposure to one or several 16-hour dark periods. The distribution of male and female inflorescences on the flowering shoot was described, and a scoring system was designed to assess the development of the female inflorescences.

Cytokinin as a Possible Component of the Floral Stimulus in Sinapis alba.

Results of previous investigations indicated that one of the early and essential events occurring in the apical meristem of Sinapis alba L. during the transition to flowering is the release to mitosis of the G(2) nuclei; the trigger to mitosis is generated in the leaves and its movement out of the leaves begins around 16 hours after the start of the inductive treatment. The mitotic wave in the meristem culminates 10 hours later.

Changes in the carbohydrate content of the leaf and the apical bud of Sinapis during transition to flowering.

Vegetative plants of Sinapis alba L. were induced to flower by a single long day of 20 h or by a single short day of 8 h starting at an unusual time of the 24-h cycle ("displaced short day"). The soluble sugar and starch contents of the just-expanded leaf and the apical bud were measured at various times after the start of each of these two photoinductive treatments.