Expression of a novel FGF in the Xenopus embryo. A new candidate inducing factor for mesoderm formation and anteroposterior specification

Development ◽  
1992 ◽  
Vol 114 (3) ◽  
pp. 711-720 ◽  
Author(s):  
H.V. Isaacs ◽  
D. Tannahill ◽  
J.M. Slack
Keyword(s):  
Specific Activity ◽  
Biological Properties ◽  
The Body ◽  
Mesoderm Induction ◽  
Gastrula Stage ◽  
Blastula Stage ◽  
Mesoderm Formation ◽  
Low Levels

We have cloned and sequenced a new member of the fibroblast growth factor family from Xenopus laevis embryo cDNA. It is most closely related to both mammalian kFGF (FGF-4) and FGF-6 but as it is not clear whether it is a true homologue of either of these genes we provisionally refer to it as XeFGF (Xenopus embryonic FGF). Two sequences were obtained, differing by 11% in derived amino acid sequence, which probably represent pseudotetraploid variants. Both the sequence and the behaviour of in vitro translated protein indicates that, unlike bFGF (FGF-2), XeFGF is a secreted molecule. Recombinant XeFGF protein has mesoderm-inducing activity with a specific activity similar to bFGF. XeFGF mRNA is expressed maternally and zygotically with a peak during the gastrula stage. Both probe protection and in situ hybridization showed that the zygotic expression is concentrated in the posterior of the body axis and later in the tailbud. Later domains of expression were found near the midbrain/hindbrain boundary and at low levels in the myotomes. Because of its biological properties and expression pattern, XeFGF is a good candidate for an inducing factor with possible roles both in mesoderm induction at the blastula stage and in the formation of the anteroposterior axis at the gastrula stage.

Single cell analysis of mesoderm formation in the Xenopus embryo

Development ◽  
1991 ◽  
Vol 111 (2) ◽  
pp. 523-530 ◽  
Author(s):  
S.F. Godsave ◽  
J.M. Slack
Keyword(s):  
Regional Differences ◽  
Single Cell Analysis ◽  
Cell Types ◽  
Mesoderm Induction ◽  
Cell Analysis ◽  
Blastula Stage ◽  
Mesodermal Cell ◽  
Mesoderm Formation ◽  
Different Cell Types

We have examined the developmental specification of individual cells in the Xenopus blastula using a new in vitro culture system. Regional differences are apparent at the mid-blastula stage when animal hemisphere cells form only ectodermal cell types, while many clones from below the pigment boundary contain mesodermal cell types. A number of clones give rise to more than one differentiated cell type indicating that the initial steps of mesoderm induction are potentially reversible. Animal hemisphere cells can be induced to form mesoderm by fibroblast growth factor (FGF). Different cell types predominate at different FGF concentrations and the neighbours in this sequence are also the pairs of cell types most usually associated in mixed clones derived from the marginal zone. We propose that the specification of individual cells depends upon both the concentration of inducing factor and on stochastic intracellular events.

scholarly journals Current Status of Putative Animal Sources of SARS-CoV-2 Infection in Humans: Wildlife, Domestic Animals and Pets

2021 ◽  
Vol 9 (4) ◽  
pp. 868
Author(s):  
Max Maurin ◽  
Florence Fenollar ◽  
Oleg Mediannikov ◽  
Bernard Davoust ◽  
Christian Devaux ◽  
...  
Keyword(s):  
Animal Species ◽  
Biological Properties ◽  
Experimental Models ◽  
Current Data ◽  
The Body ◽  
Receptor Expression ◽  
Current Status ◽  
Susceptible Animal

SARS-CoV-2 is currently considered to have emerged from a bat coronavirus reservoir. However, the real natural cycle of this virus remains to be elucidated. Moreover, the COVID-19 pandemic has led to novel opportunities for SARS-CoV-2 transmission between humans and susceptible animal species. In silico and in vitro evaluation of the interactions between the SARS-CoV-2 spike protein and eucaryotic angiotensin-converting enzyme 2 (ACE2) receptor have tentatively predicted susceptibility to SARS-CoV-2 infection of several animal species. Although useful, these data do not always correlate with in vivo data obtained in experimental models or during natural infections. Other host biological properties may intervene such as the body temperature, level of receptor expression, co-receptor, restriction factors, and genetic background. The spread of SARS-CoV-2 also depends on the extent and duration of viral shedding in the infected host as well as population density and behaviour (group living and grooming). Overall, current data indicate that the most at-risk interactions between humans and animals for COVID-19 infection are those involving certain mustelids (such as minks and ferrets), rodents (such as hamsters), lagomorphs (especially rabbits), and felines (including cats). Therefore, special attention should be paid to the risk of SARS-CoV-2 infection associated with pets.

Ontogeny of prolyl endopeptidase, pyroglutamyl peptidase I, TRH, and its metabolites in rat pancreas

1992 ◽  
Vol 262 (6) ◽  
pp. E845-E850
Author(s):  
P. Salers ◽  
L. H. Ouafik ◽  
P. Giraud ◽  
J. Y. Maltese ◽  
A. Dutour ◽  
...  
Keyword(s):  
Active Site ◽  
Specific Activity ◽  
Early Stage ◽  
Prolyl Endopeptidase ◽  
Neonatal Rat ◽  
Rat Pancreas ◽  
Low Levels ◽  
Intact Rats

We demonstrate that two enzymes, soluble unspecific pyroglutamyl peptidase I and prolyl endopeptidase, able to degrade thyrotropin-releasing hormone (TRH) in vitro were present in pancreas at the early stage of rat development. Specific particulate pyroglutamyl peptidase II remained undetectable during ontogenesis. Pyroglutamyl peptidase I specific activity increased until day 3 and decreased after day 5. Furthermore, prolyl endopeptidase specific activity rose slightly to a peak on postnatal day 20. A good correlation between immunoreactive TRH and deaminated TRH (TRH-OH) was found in the 1st wk after birth. However, His-Pro diketopiperazine (DKP) levels were stable and low during development. We show that hot acidic extraction conditions could artefactually generate His-Pro DKP. In vivo, active site-directed inhibitors of pyroglutamyl peptidase I and prolyl endopeptidase enzymes do not show any TRH-deamidating and/or pyroglutamyl peptidase I pathways in neonatal rat pancreas. The data suggest that these two enzymes are not involved in intra- or extracellular control of TRH levels in neonatal rat pancreas and that pancreatic TRH content appears to be principally regulated by biosynthetic steps. Nevertheless, low levels of endogenous His-Pro DKP and TRH-OH identified in neonatal rat pancreas suggest that TRH or TRH-like peptides may be metabolized in this tissue in intact rats, albeit at low rates.

Intercellular signalling in mesoderm formation during amphibian development

1993 ◽  
Vol 340 (1293) ◽  
pp. 287-296 ◽  
Keyword(s):  
Positional Information ◽  
Cell Types ◽  
The Body ◽  
Fibroblast Growth ◽  
Blastula Stage ◽  
Mesodermal Cell ◽  
Inductive Interaction ◽  
Mesoderm Formation ◽  
Stage Embryo ◽  
Intercellular Signalling

The mesoderm of amphibian embryos arises through an inductive interaction in which a signal from the vegetal hemisphere of the blastula-stage embryo acts on overlying equatorial cells. Strong candidates for endogenous mesoderm-inducing signals include members of the fibroblast growth factor (FGF) and activin families. In this paper we show that cells form different mesodermal cell types in response to different concentrations of these factors, and that graded distributions of activin and FGF can, in principle, provide sufficient positional information to generate the body plan of the Xenopus embryo.

FORMATION OF 17α-HYDROXY-PREGNENOLONE, 17α-HYDROXY-PROGESTERONE AND PROGESTERONE BY HYDATIDIFORM MOLES IN VITRO

1969 ◽  
Vol 61 (1) ◽  
pp. 68-75 ◽  
Author(s):  
Hubertus A. van Leusden ◽  
Maria Siemerink
Keyword(s):  
Urinary Excretion ◽  
Specific Activity ◽  
Full Term ◽  
Hydroxy Progesterone ◽  
Experimental Findings ◽  
Hydatidiform Moles ◽  
Constant Specific Activity

ABSTRACT Vesicles of hydatidiform moles were incubated in the presence of [7α-3H]pregnenolone, After the incubation and extraction of tissues and media, 17α-hydroxy-pregnenolone*, 17α-hydroxy-progesterone and progesterone were identified using a number of TLC systems, followed by crystallization to a constant specific activity. [7α-3H] pregnenolone was not converted to oestrone, 17β-oestradiol and oestriol. The experimental findings indicate that hydatidiform moles, like full term placentas, are deficient in the enzymes necessary to convert C21 to C19 steroids. The production of 17α-hydroxy-progesterone and progesterone in the molar trophoblast in situ may contribute to the considerable urinary excretion of pregnanetriol and pregnanediol in patients with hydatidiform moles.

Peripheral metabolism of PTH: fate of biologically active amino terminus in vivo

1988 ◽  
Vol 255 (6) ◽  
pp. E886-E893 ◽  
Author(s):  
F. R. Bringhurst ◽  
A. M. Stern ◽  
M. Yotts ◽  
N. Mizrahi ◽  
G. V. Segre ◽  
...  
Keyword(s):  
Specific Activity ◽  
Limited Proteolysis ◽  
High Specific Activity ◽  
Biologically Active ◽  
Amino Terminal ◽  
Liver And Kidney ◽  
Low Levels ◽  
Peripheral Metabolism

Clearance of intact parathyroid hormone (PTH) from blood is associated with rapid uptake by liver and kidney, limited proteolysis by tissue endopeptidases and, within minutes, appearance of circulating carboxyl-(COOH)-terminal PTH fragments. The fate of the corresponding amino(NH2)-terminal portion of the hormone during this peripheral metabolism is still unknown, however. To determine this, we have employed [35S]bovine PTH (bPTH) labeled to high specific activity at NH2-terminal methionines, which permits direct monitoring of the fate of the PTH NH2-terminus during metabolism in vivo. The [35S]PTH was administered by bolus or continuous intravenous infusion to anesthetized normal rats, to rats subjected to acute ablation of the liver, the kidneys, or both, and to rats receiving co-infusions of excess synthetic bPTH(1-34) NH2-terminal fragments. Analysis by high-resolution chromatographic techniques sensitive to 10(-13) M [35S]PTH peptides in plasma yields no evidence that peripheral metabolism of PTH generates circulating NH2-terminal fragments, even when special measures are taken to block clearance of such putative fragments from blood. We find that the NH2-terminus of PTH is rapidly degraded in situ by the liver but that both liver and especially kidney nevertheless contain low levels of NH2-terminal PTH fragments that, although not released into the blood, are large enough to be potentially active. Thus, the peripheral metabolism of PTH in normal animals does not normally lead to the formation of circulating amino terminal fragments of the hormone that might act independently of intact PTH on peripheral target tissues.

scholarly journals Microtubule behavior during guidance of pioneer neuron growth cones in situ.

1991 ◽  
Vol 115 (2) ◽  
pp. 381-395 ◽  
Author(s):  
J H Sabry ◽  
T P O'Connor ◽  
L Evans ◽  
A Toroian-Raymond ◽  
M Kirschner ◽  
...  
Keyword(s):  
Growth Cone ◽  
Growth Cones ◽  
The Body ◽  
Microtubule Network ◽  
Guidance Cues ◽  
Selective Retention ◽  
Pioneer Neuron ◽  
Neuron Growth

The growth of an axon toward its target results from the reorganization of the cytoskeleton in response to environmental guidance cues. Recently developed imaging technology makes it possible to address the effect of such cues on the neural cytoskeleton directly. Although high resolution studies can be carried out on neurons in vitro, these circumstances do not recreate the complexity of the natural environment. We report here on the arrangement and dynamics of microtubules in live neurons pathfinding in response to natural guidance cues in situ using the embryonic grasshopper limb fillet preparation. A rich microtubule network was present within the body of the growth cone and normally extended into the distal growth cone margin. Complex microtubule loops often formed transiently within the growth cone. Branches both with and without microtubules were regularly observed. Microtubules did not extend into filopodia. During growth cone steering events in response to identified guidance cues, microtubule behaviour could be monitored. In turns towards guidepost cells, microtubules selectively invaded branches derived from filopodia that had contacted the guidepost cell. At limb segment boundaries, microtubules displayed a variety of behaviors, including selective branch invasion, and also invasion of multiple branches followed by selective retention in branches oriented in the correct direction. Microtubule invasion of multiple branches also was seen in growth cones migrating on intrasegmental epithelium. Both selective invasion and selective retention generate asymmetrical microtubule arrangements within the growth cone, and may play a key role in growth cone steering events.

scholarly journals Macrophages phagocytose thymic lymphocytes with productively rearranged T cell receptor alpha and beta genes.

1988 ◽  
Vol 168 (6) ◽  
pp. 2279-2294 ◽  
Author(s):  
K Inaba ◽  
M Inaba ◽  
T Kinashi ◽  
K Tashiro ◽  
M Witmer-Pack ◽  
...  
Keyword(s):  
T Cell Receptor ◽  
Buoyant Density ◽  
Cell Receptor ◽  
Lymphoid Tissues ◽  
Double Positive ◽  
High Turnover ◽  
Mhc Molecules ◽  
Low Levels

The thymus gland is important for the formation of competent T lymphocytes. However, there is long-standing evidence that greater than 95% of newly formed thymocytes do not emigrate to peripheral lymphoid tissues but instead die locally. We have identified a rapid and selective pathway for thymocyte turnover in vitro. The mechanism entails binding, uptake, and digestion by macrophages. The susceptible cells are a subpopulation of double-positive thymocytes. These thymocytes can be enriched by virtue of their high buoyant density in Percoll and prove to have low levels of surface CD3 and little or no surface TCR. However TCR-alpha and -beta genes have undergone rearrangement, and full length alpha and beta transcripts are abundant. Therefore many double-positive cells rearrange and express TCR genes but do not have normal levels of TCR on the cell surface. We propose that thymocytes that undergo high turnover in situ are unable to form receptors that can be selected by MHC molecules in the thymus, and that these cells are recognized and cleared by the macrophage.

scholarly journals Relative Expression Levels Rather Than Specific Activity Plays the Major Role in Determining In Vivo AKT Isoform Substrate Specificity

2011 ◽  
Vol 2011 ◽  
pp. 1-18 ◽  
Author(s):  
Rachel S. Lee ◽  
Colin M. House ◽  
Briony E. Cristiano ◽  
Ross D. Hannan ◽  
Richard B. Pearson ◽  
...  
Keyword(s):  
Substrate Specificity ◽  
Specific Activity ◽  
Dominant Role ◽  
Protein Substrates ◽  
Cellular Processes ◽  
Disease States ◽  
The Individual

The AKT protooncogene mediates many cellular processes involved in normal development and disease states such as cancer. The three structurally similar isoforms: AKT1, AKT2, and AKT3 exhibit both functional redundancy and isoform-specific functions; however the basis for their differential signalling remains unclear. Here we show that in vitro, purified AKT3 is ∼47-fold more active than AKT1 at phosphorylating peptide and protein substrates. Despite these marked variations in specific activity between the individual isoforms, a comprehensive analysis of phosphorylation of validated AKT substrates indicated only subtle differences in signalling via individual isoforms in vivo. Therefore, we hypothesise, at least in this model system, that relative tissue/cellular abundance, rather than specific activity, plays the dominant role in determining AKT substrate specificity in situ.

Revamping squid gladii to biodegradable composites: In situ grafting of polyaniline to β-chitin and their antibacterial activity

2020 ◽  
pp. 088391152097323
Author(s):  
Jolleen Natalie I Balitaan ◽  
Gloricel Anne V Martin ◽  
Karen S Santiago
Keyword(s):  
Antibacterial Activity ◽  
Wound Care ◽  
Oxidative Polymerization ◽  
Biological Properties ◽  
Health Concern ◽  
Diffusion Method ◽  
Seafood Industry ◽  
Zones Of Inhibition

The global health concern on wound care is becoming more challenging with the emerging prevalence of inexorable antibiotic resistance. Amidst this crisis, various material innovations have been made to combat this dilemma. Herein, squid pens, which are regarded as discards in the seafood industry, were biorefined into β-chitin-graft-polyaniline (β-chitin-g-PANI) composites for possible wound dressing development. β-chitin was first chemically extracted from gladii, and was then grafted with PANI via in situ chemical oxidative polymerization of various concentrations of aniline, to produce the β-chitin-g-PANI composites. Supporting data from FTIR, UV-Vis, SEM, TGA, and DSC suggest that β-chitin was successfully grafted with PANI. Moreover, improved conductivity and in vitro degradation of the composites were observed as compared to β-chitin and PANI alone, respectively. Zones of inhibition observed from agar diffusion method suggest that the synthesized composites have antibacterial activity against E. coli and S. aureus. The resulting physicochemical and biological properties of integrating conducting PANI to β-chitin substantiated and rendered the β-chitin-g-PANI composites desirable candidates for the development wound care products.

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