Development of the Xenopus laevis hatching gland and its relationship to surface ectoderm patterning

Development ◽  
1991 ◽  
Vol 111 (2) ◽  
pp. 469-478 ◽  
Author(s):  
T.A. Drysdale ◽  
R.P. Elinson
Keyword(s):  
Retinoic Acid ◽  
Tyrosine Hydroxylase ◽  
Xenopus Laevis ◽  
Ciliated Cells ◽  
Surface Ectoderm ◽  
Gland Cells ◽  
The Face ◽  
Underlying Mechanisms ◽  
Development Proceeds ◽  
Hatching Gland

An antibody that recognizes tyrosine hydroxylase can be used as a marker for hatching gland cells in Xenopus embryos. Using this marker, we have shown that hatching gland cells are induced at the end of gastrulation and that presumptive hatching gland cells are localized to the anterior neural folds in Xenopus. The movements of neurulation bring the hatching gland cells together to form a characteristic Y pattern on the dorsoanterior surface of the head. The Y pattern delineates several zones of surface ectoderm which can be visualized by the presence or absence of ciliated cells. As development proceeds the hatching gland pattern is altered, demonstrating the active changes involved in forming the face. Lithium, UV irradiation and retinoic acid can be used to alter the hatching gland pattern in specific ways which help to understand the underlying mechanisms of ectodermal patterning.

scholarly journals The effect of intrinsic physiological traits on diapause survival and their underlying mechanisms in an annual bee species Bombus impatiens

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Erin Treanore ◽  
Etya Amsalem
Keyword(s):  
Oxidative Stress ◽  
Life Stage ◽  
Mass Gain ◽  
Nutrient Acquisition ◽  
Bombus Impatiens ◽  
Factors Affecting ◽  
Age Related ◽  
The Face ◽  
Underlying Mechanisms ◽  
Age Range

Abstract In the face of insect declines, identifying phases of the life cycle when insects are particularly vulnerable to mortality is critical to conservation efforts. For numerous annual insect groups, diapause is both a key adaptation that allows survival of inhospitable conditions and a physiologically demanding life stage that can result in high rates of mortality. As bees continue to garner attention as a group experiencing high rates of decline, improving our understanding of how annual bees prepare for diapause and identifying factors that reduce survival is imperative. Here, we studied factors affecting diapause survival length and their underlying mechanisms using an economically and ecologically important annual bee species, Bombus impatiens. We examined how age and mass upon diapause onset correlate with diapause survival length, and the mechanistic role of nutrient acquisition and oxidative stress post pupal eclosion in mediating these effects. Our findings show that both age and mass were strong predictors of diapause survival length. Heavier queens or queens in the age range of ~6–17 days survived longer in diapause. Mass gain was attributed to increases in lipid, protein and glycerol amounts following pupal eclosion, and the ability to deal with oxidative stress was significantly compromised in older pre-diapause queens. Our results demonstrate that age-related shifts in bee physiology and timing of nutrient acquisition may both be critical factors driving diapause survival.

Temporally-regulated retinoic acid depletion produces specific neural crest, ocular and nervous system defects

Development ◽  
1997 ◽  
Vol 124 (16) ◽  
pp. 3111-3121 ◽  
Author(s):  
E.D. Dickman ◽  
C. Thaller ◽  
S.M. Smith
Keyword(s):  
Nervous System ◽  
Retinoic Acid ◽  
Neural Crest ◽  
Female Rats ◽  
Retinoid Receptor ◽  
Knock Out ◽  
The Face ◽  
Normal Males ◽  
Temporal Events ◽  
Null Mutant Mice

Both retinoid receptor null mutants and classic nutritional deficiency studies have demonstrated that retinoids are essential for the normal development of diverse embryonic structures (e.g. eye, heart, nervous system, urogenital tract). Detailed analysis of retinoid-modulated events is hampered by several limitations of these models, including that deficiency or null mutation is present throughout gestation, making it difficult to isolate primary effects, and preventing analysis beyond embryolethality. We developed a mammalian model in which retinoid-dependent events are documented during distinct targeted windows of embryogenesis. This was accomplished through the production of vitamin A-depleted (VAD) female rats maintained on sufficient oral retinoic acid (RA) for growth and fertility. After mating to normal males, these RA-sufficient/VAD females were given oral RA doses which allowed for gestation in an RA-sufficient state; embryogenesis proceeded normally until retinoids were withdrawn dietarily to produce a sudden, acute retinoid deficiency during a selected gestational window. In this trial, final RA doses were administered on E11.5, vehicle at E12.5, and embryos analyzed on E13.5; during this 48 hour window, the last RA dose was metabolized and embryos progressed in a retinoid-deficient state. RA-sufficient embryos were normal. Retinoid-depleted embryos exhibited specific malformations of the face, neural crest, eyes, heart, and nervous system. Some defects were phenocopies of those seen in null mutant mice for RXR alpha(−/−), RXR alpha(−/−)/RAR alpha(−/−), and RAR alpha(−/−)/RAR gamma(−/−), confirming that RA transactivation of its nuclear receptors is essential for normal embryogenesis. Other defects were unique to this deficiency model, showing that complete ligand ‘knock-out’ is required to see those retinoid-dependent events previously concealed by receptor functional redundancy, and reinforcing that retinoid receptors have separate yet overlapping contributions in the embryo. This model allows for precise targeting of retinoid form and deficiency to specific developmental windows, and will facilitate studies of distinct temporal events.

scholarly journals Oviposition and development in the glass frog Hyalinobatrachium orientale (Anura: Centrolenidae)

2015 ◽  
Vol 14 (1) ◽  
pp. 3 ◽  
Author(s):  
Mohsen Nokhbatolfoghahai ◽  
Christopher J. Pollock ◽  
J. Roger Downie
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Small Area ◽  
Tail Length ◽  
Oral Disc ◽  
Progressive Development ◽  
Gland Cells ◽  
Developmental Features ◽  
Hatching Gland ◽  
Scanning Electron

Oviposition and development in the glass frog Hyalinobatrachium orientale (Anura: Centrolenidae). Oviposition and external embryonic developmental features are described in the Tobago glass frog, Hyalinobatrachium orientale. Egg clutches are nearly always laid on the undersides of leaves (one exception); usually leaves of Heliconia sp. are used, but Philodendron and palms may be used in the absence of Heliconia. Clutches contain 28.0 ± 5.3 eggs (mean ± SD) and eggs are 1.86 ± 0.11 mm in diameter. The behavior of one amplectant pair was followed for more than five hours; the pair rotated several times around a small area of the leaf depositing eggs in a tight spiral formation. External embryonic features were observed by scanning electron microscopy. Surface ciliation is extensive up to the time of hatching when it is lost; external gills are short and a cement gland is absent. Hatching gland cells were detectable on the anterodorsal surface of the head from Day 4 after deposition and persisted until at least Day 10, and hatching occurred between Days 9 and 16. During this period, progressive development in tail length, surface pigmentation, intestinal coiling, and oral disc features was observed. Post-hatching larvae reared for six weeks grew 37% in length and tripled in weight, but remained at Gosner Stage 25.

scholarly journals Secretion of a cytoplasmic lectin from Xenopus laevis skin.

1986 ◽  
Vol 102 (2) ◽  
pp. 492-499 ◽  
Author(s):  
N C Bols ◽  
M M Roberson ◽  
P L Haywood-Reid ◽  
R F Cerra ◽  
S H Barondes
Keyword(s):  
Electron Microscope ◽  
Xenopus Laevis ◽  
Mucous Gland ◽  
Gland Cells ◽  
Binding Lectin

The skin of Xenopus laevis contains a soluble beta-galactoside-binding lectin with a approximately 16,000-mol-wt subunit. It resembles similar lectins purified from a variety of tissues from other vertebrates, and differs from two other soluble X. laevis lectins from oocytes and serum that bind alpha-galactosides. The skin lectin is concentrated in the cytoplasm of granular gland and mucous gland cells, as demonstrated by immunohistochemistry with the electron microscope. Upon injection with epinephrine, there is massive secretion of the cytoplasmic lectin from the granular gland cells.

Long-term modulation of tyrosine hydroxylase activity and expression by endothelin-1 and -3 in the rat anterior and posterior hypothalamus

2008 ◽  
Vol 294 (3) ◽  
pp. R905-R914 ◽  
Author(s):  
Guadalupe Perfume ◽  
Sabrina L. Nabhen ◽  
Karla Riquelme Barrera ◽  
María G. Otero ◽  
Liliana G. Bianciotti ◽  
...  
Keyword(s):  
Tyrosine Hydroxylase ◽  
Cardiovascular Effects ◽  
Receptor Activation ◽  
Catecholaminergic Neurons ◽  
Endothelin System ◽  
Catecholaminergic Transmission ◽  
Underlying Mechanisms ◽  
G Protein Coupled ◽  
The Brain

Brain catecholamines are involved in the regulation of biological functions, including cardiovascular activity. The hypothalamus presents areas with high density of catecholaminergic neurons and the endothelin system. Two hypothalamic regions intimately related with the cardiovascular control are distinguished: the anterior (AHR) and posterior (PHR) hypothalamus, considered to be sympathoinhibitory and sympathoexcitatory regions, respectively. We previously reported that endothelins (ETs) are involved in the short-term tyrosine hydroxylase (TH) regulation in both the AHR and PHR. TH is crucial for catecholaminergic transmission and is tightly regulated by well-characterized mechanisms. In the present study, we sought to establish the effects and underlying mechanisms of ET-1 and ET-3 on TH long-term modulation. Results showed that in the AHR, ETs decreased TH activity through ETB receptor activation coupled to the nitric oxide, phosphoinositide, and CaMK-II pathways. They also reduced total TH level and TH phosphorylated forms (Ser 19 and 40). Conversely, in the PHR, ETs increased TH activity through a G protein-coupled receptor, likely an atypical ET receptor or the ETC receptor, which stimulated the phosphoinositide and adenylyl cyclase pathways, as well as CaMK-II. ETs also increased total TH level and the Ser 19, 31, and 40 phosphorylated sites of the enzyme. These findings support that ETs are involved in the long-term regulation of TH activity, leading to reduced sympathoinhibition in the AHR and increased sympathoexcitation in the PHR. Present and previous studies may partially explain the cardiovascular effects produced by ETs when applied to the brain.

Novel retinoic acid generating activities in the neural tube and heart identified by conditional rescue of Raldh2 null mutant mice

Development ◽  
2002 ◽  
Vol 129 (9) ◽  
pp. 2271-2282 ◽  
Author(s):  
Felix A. Mic ◽  
Robert J. Haselbeck ◽  
Arnold E. Cuenca ◽  
Gregg Duester
Keyword(s):  
Spinal Cord ◽  
Retinoic Acid ◽  
Neural Tube ◽  
The Novel ◽  
Vertebrate Development ◽  
Targeted Disruption ◽  
Surface Ectoderm ◽  
Eye Field ◽  
Null Mutant Mice ◽  
Dorsal Retina

Retinoid control of vertebrate development depends upon tissue-specific metabolism of retinol to retinoic acid (RA). The RA biosynthetic enzyme RALDH2 catalyzes much, but not all, RA production in mouse embryos, as revealed here with Raldh2 null mutants carrying an RA-responsive transgene. Targeted disruption of Raldh2 arrests development at midgestation and eliminates all RA synthesis except that associated with Raldh3 expression in the surface ectoderm of the eye field. Conditional rescue of Raldh2–/– embryos by limited maternal RA administration allows development to proceed and results in the establishment of additional sites of RA synthesis linked to Raldh1 expression in the dorsal retina and to Raldh3 expression in the ventral retina, olfactory pit and urinary tract. Unexpectedly, conditionally rescued Raldh2–/– embryos also possess novel sites of RA synthesis in the neural tube and heart that do not correspond to expression of Raldh1-3. RA synthesis in the mutant neural tube was localized in the spinal cord, posterior hindbrain and portions of the midbrain and forebrain, whereas activity in the mutant heart was localized in the conotruncus and sinus venosa. In the posterior hindbrain, this novel RA-generating activity was expressed during establishment of rhombomeric boundaries. In the spinal cord, the novel activity was localized in the floorplate plus in the intermediate region where retinoid-dependent interneurons develop. These novel RA-generating activities in the neural tube and heart fill gaps in our knowledge of how RA is generated spatiotemporally and may, along with Raldh1 and Raldh3, contribute to rescue of Raldh2–/– embryos by producing RA locally.

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