Search results for "Embryon"
showing 10 items of 988 documents
Embryonic development of corkwing wrasse, Symphodus melops
2016
Master's thesis Aquatic Ecology BIO500 - University of Agder 2016 Eggs from corkwing wrasse, Symphodus melops were described, photographed and illustrated to characterise the embryonic development of this species. Egg development was divided into 8 stages from fertilisation until hatching with descriptions of key features for each stage. The rate of development in corkwing wrasse eggs at temperatures commonly found along the Norwegian coast (12, 15 and 18 C) was also investigated. The rate of development was faster at higher temperatures. Keywords: labridae, cleaner fish, embryonic development, corkwing wrasse
Bleomycin: Action on growth of oncogenic RNA viruses and on cell transformation
1975
Bleomycin (BLM) inhibits cell proliferation of noninfected chick embryo fibroblasts by blocking their DNA synthesis selectively. Chick embryo fibroblasts have beentransformed by Schmidt-Ruppin D strain of Rous Sarcoma Virus. Transformation has been determined by a focus assay. Foci formation is strongly reduced by BLM. Virus replication is inhibited by BLM in growing and confluent monolayer cells. This result might be explained by the observation that this drug reduces proliferation of growing and of confluent monolayer cells very sensitively. During the first 24 hours after infection the BLM inhibitory effect is more pronounced than in the case of BLM-application during the period 24--48 h…
Species size affects hatching response to different temperature regimes in a rotifer cryptic species complex
2013
The strategy of decreasing size with increasing temperature known as Bergmann’s rule operates at geographic scale and in spite of extensive studies still presents a puzzle to researches. The aim of this work was to verify whether patterns of diapausing egg hatching of closely related species are consistent with the expectations from Bergmann’s rule. In a laboratory study of the cryptic species complex of the rotifer Brachionus plicatilis, the response to temperature (17.5, 22.5, and 25.0 °C) of diapausing eggs collected in a pond where the three tested species coexist was assessed by (1) the number of hatchlings emerging or (2) the time needed to hatch. Our results show that the response to…
Relationship between egg features and maternal body size in the simultaneous hermaphrodite Oxynoe olivacea (Mollusca, Opisthobranchia, Sacoglossa)
2005
This paper provides information on spawn morphology and egg features of the stenophagous planktotrophic Mediterranean sacoglossan Oxynoe olivacea. Smith and Fretwell’s hypothesis, predicting that individuals of the same population growing in the same environmental conditions and varying in size should spawn eggs of a constant size, was tested in a population of O. olivacea living in the Straits of Messina. To determine whether (a) spawn mass size, (b) total egg number per spawn, and (c) egg size were related to parent size of O. olivacea, 21 egg masses (seven egg masses deposited by seven different 20 mm animals, seven egg masses deposited by seven different 25 mm animals and seven egg mass…
Ionic currents ofdrosophila embryonic neurons derived from selectively cultured CNS midline precursors
2000
In order to investigate the electrogenesis of defined cell populations, we applied an in vitro system that allows the selective culturing of individual Drosophila CNS precursors under different conditions. CNS midline (ML) precursors prepared from gastrula stage embryos gave rise to progeny cells with neuronal and glial morphology that expressed specific markers. Using whole-cell patch-clamp recordings, a detailed description of ionic currents present in this defined cell population is provided. Most ionic currents of cultured ML neurons were similar to other cultured Drosophila neurons, even though their embryonic origin is different. They displayed at least two voltage-gated potassium cur…
Running against time: conservation of the remaining hawksbill turtle (Eretmochelys imbricata) nesting population in the Dominican Republic
2012
Saona Island hosts the last hawksbill turtle (Eretmochelys imbricata) nesting population in the Dominican Republic, which has experienced a severe decline in the last decades, mostly due to illegal egg take. Here we present the results of an artificial incubation programme started in 2007 to protect the clutches from human predation. A preliminary survey in 2006 showed that about 60% of clutches laid were taken by humans. Over the study period (2007–2010) we recorded 400 clutches, of which 38.2% were predated by humans, 40.7% were artificially incubated and 21% were incubated in situ. Overall, the artificial incubation programme allowed the release of 12,340 hatchlings. No differences were …
Evidence from mtDNA RFLP analysis for the introduction of Fundulus heteroclitus to southwestern Spain
1996
Restriction analysis of mitochondrial DNA confirmed the taxonomic status of a southwestern Iberian Peninsula population of Fundulus heteroclitus and its probable origin in North America.
Cell lineage and cell fate specification in the embryonic CNS of Drosophila.
1997
The Drosophila CNS derives from a population of neural stem cells, called neuroblasts (NBs), which delaminate individually from the neurogenic region of the ectoderm. In the embryonic ventral nerve cord each NB can be uniquely identified and gives rise to a specific lineage consisting of neurons and/or glial cells. This 'NB identity' is dependent on the position of the progenitor cells in the neuroectoderm before delamination. The positional information is provided by the products of segment polarity and dorsoventral (D/V) patterning genes. Subsequently, 'cell fate genes' like huckebein (hkb) and eagle (eg) contribute to the generation of specific NB lineages. These genes act downstream of …
Identification Of Mitotically Competent SOX2+ Cells In White Matter Of Normal Human Adult Brain
2011
AbstractSOX2 expression is linked to the undifferentiated state of stem cells in mammalian neurogenic niches. While its expression has been reported in the adult human subventricular zone (SVZ), to date it has not been detected in adult human white matter. Here we describe a population of SOX2+ cells from the white matter of the adult human temporal lobe, which proliferate and express glial markers in vitro.
Decorin Expression and Oncosuppression in Human Embryonic Carcinomas
2019
Human embryonic stem cells in culture can transform into malignant, cancer-like cells exhibiting lesser differentiation. After transplantation, these transformed cells can form highly malignant germ cell tumors. In humans, germ cell tumors often appear at gonadal sites, like in the testis. In this study, we examined the expression of small leucine rich proteoglycans in normal and karyotypically abnormal human embryonic stem cells using a publicly available transcriptome data. We also examined the expression of the small leucine rich proteoglycans in healthy human testis and in different human testicular non-seminoma germ cell tumors using IST Online database. Furthermore, we localized the e…