Basal lamina heparan sulphate proteoglycan is involved in otic placode invagination in chick embryos

Producción CientíficaInvagination of other cup-shaped organ primordia. It is known that the cellular cytoskele- ton plays a Abstract Formation of the otocyst from the otic placode appears to differ from limited role in otic placode invagination, whilst the extracellular matrix underlying the otic pri- mordium intervenes in the folding process. In this study we have analysed the role of the basal lamina heparan sulphate proteoglycan in otic primordium invagination. At 10 H.H. stage, heparan sulphate proteoglycan im- the otic epithelium. Our findings support the theory that otic primordium invagination may be regulated, at least in part, by the basal lamina components, which might contribute towards anchoring the otic epithelium to adja- cent structures. Key words Otic development • Heparinase • Microinjection • Epithelial folding • Extracellular matrix munomarking begins to appear on the otic placode basal lamina, increasing noticeably at 13 H.H. stage, coincid- ing with maximum folding of the otic epithelium, and is still present at later stages. Enzyme degradation of hepa- ran sulphate proteoglycan in the otic primordium basal lamina, by means of microinjection with heparinase III prior to folding, significantly disrupts invagination of the otic placode, which remains practically flat, with a sig- nificant reduction in the depth of the otic pit and an in- crease in the diameter of the otic opening. The immuno- cytochemistry analysis revealed a notable depletion of basal lamina heparan sulphate proteoglycan in the otic primordia microinjected with heparinase, with no statis- tically significant differences observed in the volume or rate of cell proliferation in the otic epithelium relative to the control, which suggests that heparan sulphate prot- eoglycan disruption does not interfere with the epithelial growth. In addition, a study of apoptosis distribution by the TUNEL method confirmed that treatment with hepa- rinase does not cause interference with cell survival i

Prenatal expression of interleukin 1B and interleukin 6 in the rat pituitary gland

Producción CientíficaIt is known that interleukin 1b (IL-1b) and interleukin 6 (IL-6) are expressed post-natally in normal and tumoral cells in the anterior pituitary, and that they play a role in both the liberation of different hormones and in the growth, proliferation and tumor formation of the pituitary gland. However, their expression and role during embryonic and fetal development remain unknown. We have performed an immunocytochemistry study of prenatal expression and distribution of IL-1b and IL-6 in isolated embryonic rat Rathke’s pouch prior to birth, more specifically between 13.5 and 19.5 days p.c. Western-blot analysis carried out on 19.5-day p.c. embryos showed positive immunolabelling for IL-1b and IL-6. These interleukins were initially expressed simultaneously in the rostral and ventral portions of Rathke’s pouch in 15.5-day p.c. embryos, and this expression progressed caudodorsally in later developmental stages, extending to most of the hypophysis before birth. The number of cells expressing these interleukins increased throughout this period: 48.22% of anterior pituitary cells expressed IL-6 in 19.5-day embryos, whilst IL-1b was positive in 39.8% of the cells. Moreover, we have demonstrated that some adenohypophyseal cells co-express both interleukins. Such findings represent the first step towards an understanding of the physiological role of these interleukins in anterior pituitary development

Embryonic cerebrospinal fluid regulates neuroepithelial survival proliferation and neurogenesis in chick embryos

Producción CientíficaEarly in development, the behavior of neuroepithelial cells is controlled by several factors, which act in a developmentally regulated manner. Dif- fusible factors are secreted locally by the neuroepithelium itself, although other nearby structures may also be involved. Evidence suggests a physio- logical role for the cerebrospinal fluid in the development of the brain. Here, using organotypic cultures of chick embryo neuroepithelial explants from the mesencephalon, we show that the neuroepithelium in vitro is not able to self-induce cell survival, replication, and neurogenesis. We also show that the embryonic cerebrospinal fluid (E-CSF) promotes neuroepithelial stem cell survival and induces proliferation and neurogenesis in mesencephalic explants. These data strongly suggest that E-CSF is involved in the regu- lation of neuroepithelial cells behavior, supporting the hypothesis that this fluid plays a key role during the early development of the central nervous system

Early embryonic brain development in rats requieres the trophic influence of cerebrospinal fluid

Producción CientíficaParticularly evCerebrospinal fluid has shown itself to be an essential brain component during development. This is parident at the earliest stages of development where a lot of research, performed mainly in chick embryos, supports the evidence that cerebrospinal fluid is involved in different mechanisms controlling brain growth and morphogenesis, by exerting a trophic effect on neuroepithelial precursor cells (NPC) involved in controlling the behaviour of these cells. Despite it being known that cerebrospinal fluid in mammals is directly involved in corticogenesis at fetal stages, the influence of cerebrospinal fluid on the activity of NPC at the earliest stages of brain development has not been demonstrated. Here, using ‘‘in vitro’’ organotypic cultures of rat embryo brain neuroepithelium in order to expose NPC to or deprive them of cerebrospinal fluid, we show that the neuroepithelium needs the trophic influence of cerebrospinal fluid to undergo normal rates of cell survival, replication and neurogenesis, suggesting that NPC are not self-sufficient to induce their normal activity. This data shows that cerebrospinal fluid is an essential component in chick and rat early brain development, suggesting that its influence could be constant in higher vertebrates

Role of interleukin 1B in the control of neuropithelial proliferation and differentiation of the spinal cord during development

Producción CientíficaInterleukin-1b (IL-1b) is an important trophic factor in the nervous system (NS). IL-1b is ubiquitously expressed from very early stages during the development of the amphibian NS and its action has been demonstrated in vitro on survival, proliferation and differ- entiation in mammalian embryos. In this report, we show that IL-1b is immunocytochemically expressed in embryonic spinal cord from early stages, both in rat (embryonic day 12) and in chicken (stage 17-HH), in neuroepithelial cells and nerve fibres, dorsal root ganglia, anterior and posterior roots of the spinal nerves, and in the fibres of these nerves. Our in vivo experiments on chick embryos, with micro- beads impregnated with IL-1b implanted laterally to the spinal cord at the level of the wing anlage, demonstrate that this cytokine pro- duces a statistically significant increase in nuclear incorporation of BrdU at the dorsal level and a reduction of this at the ventral level, whereas local immunoblocking with anti-IL-1b antibodies causes a dorsal reduction of BrdU incorporation and alters ventral differen- tiation. These data demonstrate that IL-1b plays a part in controlling proliferation and early differentiation during the development of the spinal cord in chick embryos

Retinoic acid, under cerebrospinal fluid control, induces neurogenesis during early brain development

Producción CientíficaOne of the more intriguing subjects in neuroscience is how a precursor or stem cell is induced to differentiate into a neuron. Neurogenesis begins early in brain development and suddenly becomes a very intense process, which is related with the influence of Retinoic Acid. Here, using a biological test (F9-1.8 cells) in chick embryos, we show that ―in vivo‖ embryonic cerebrospinal fluid regulates mesencephalic-rombencephalic Isthmic Retinoic Acid synthesis and this effect has a direct influence on mesencephalic neuroepithelial precursors, inducing a significant increase in neurogenesis. This effect is mediated by the Retinol Binding Protein present in the embryonic cerebrospinal fluid. The knowledge of embryonic neurogenetic stimulus could be useful in the control of adult brain neurogenesis.Ministerio de Educación y Ciencia (BFU207/6516)Junta de Castilla y León (Consejería de Educación, GR195

Chondroitin sulphate mediated fusion of brain: neural folds in rat embryons

Producción CientíficaPrevious studies have demonstrated that during neural fold fusion in different species, an apical extracellular material rich in glycoconjugates is involved. However, the composi- tion and the biological role of this material remain undeter- mined. In this paper, we show that this extracellular matrix in rat increases notably prior to contact between the neural folds, suggesting the dynamic behaviour of the secretory process. Immunostaining has allowed us to demonstrate that this extracellular matrix contains chondroitin sulphate proteoglycan (CSPG), with a spatio-temporal distribution pattern, suggesting a direct relationship with the process of adhesion. The degree of CSPG involvement in cephalic neu- ral fold fusion in rat embryos was determined by treatment with specific glycosidases. In vitro rat embryo culture and microinjection techniques were employed to carry out se- lective digestion, with chondroitinase AC, of the CSPG on the apical surface of the neural folds; this was done immediately prior to the bonding of the cephalic neural folds. In all the treated embryos, cephalic defects of neural fold fusion could tant role in the fusion of the cephalic neural folds in rat em- bryos, which implies that this proteoglycan could be in- volved in cellular recognition and adhesion. Abbreviations used in this paper CSPG chondroitin sulphate proteoglycan HSPG heparan sulphate proteoglycan PBS phosphate-buffered saline SEM scanning electron microscopy be detected. These results show that CSPG plays an impor

Lens capsule HSPG-Perlecan regulates lens fibre differentiation during chick embryo development

Producción CientíficaLens fibre differentiation is a life-long process related with lens transparency, and is particularly intense during development, being related with an FGF-2 antero-posterior gradient at the equator level as the main growth factor involved which has been related with the basal membrane of the lens anlagen known as “Lens capsule”. However the lens fibre differentiation induced by FGF2 depends, as in other biological systems, on the local bioavailability of FGF-2 regulated by their relationship with extracellular matrix molecules as Heparan Sulphate Proteoglycans. Here, we try to clarify how Perlecan (a heparan sulphate proteoglycan specific from basement membranes) is involved in lens fibre differentiation at earliest stages of eye development. Our results show that Perlecan, is a major component in the lens capsule during the earliest stages of lens development in chick embryos being present during lens plate induction, lens vesicle stage and the onset of lens fibre differentiation. In order to demonstrate a direct involvement of HSPG-Perlecan in lens fibre differentiation, we generate depleted lenses by HSPG-Perlecan synthesis disruption and specific enzymatic digestion. The HSPG-Perlecan depleted lens show a significant delay or abolition in the lens fibre differentiation which remains in an immature cells displaying DNA synthesis in the posterior epithelium and a decrease in FGF2 lens expression. These data support the hypothesis that lens capsule HSPG-Perlecan is a key molecule involved in lens fibre differentiation during development, probably by involvement in FGF-2 biodisponibility.Ministerio de Educación y Ciencia (Grant BFU207/6516)Instituto de Salud Carlos III (Grant PIO20961)Junta de Castilla y León (Grants VA21A07, VA049/04, SAN673/VA15/08

Embryonic Cerebrospinal Fluid Activates Neurogenesis of Neural Precursors within the Subventricular Zone of the Adult Mouse Brain

Producción CientíficaIntroduction: There is a nondeveloped neurogenic potential in the adult mammalian brain, which could be the basis for neuroregenerative strategies. Many research efforts have been made to understand the control mechanisms which regulate the transition from a neural precursor to a neuron in the adult brain. Embryonic cerebrospinal fluid (CSF) is a complex fluid which has been shown to play a key role in neural precursor behavior during development, working as a powerful neurogenic inductor. We tested if the neurogenic properties of embryonic CSF are able to increase the neurogenic activity of neuronal precursors from the subventricular zone (SVZ) in the brains of adult mice. Results: Our results show that mouse embryonic CSF significantly increases the neurogenic activity in precursor cells from adult brain SVZ. This intense neurogenic effect was specific for embryonic CSF and was not induced by adult CSF. Conclusions: Embryonic CSF is a powerful neurogenesis inductor in homologous neuronal precursors in the adult brain. This property of embryonic CSF could be a useful tool in neuroregeneration strategies

Muerte celular en el desarrollo

Se explican los dos tipos fundamentales de muerte celular (necrosis y apoptosis), así como su proceso, funciones y malformaciones congénitas relacionadasDepartamento de Anatomía y Radiologí