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Lanche Capel - One of the best experts on this subject based on the ideXlab platform.
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four dimensional analysis of vascularization during primary development of an organ the Gonad
Proceedings of the National Academy of Sciences of the United States of America, 2008Co-Authors: Douglas Coveney, Jonah Cool, Tim Olive, Lanche CapelAbstract:Time-lapse microscopy has advanced our understanding of yolk sac and early embryonic vascularization. However, it has been difficult to assess endothelial interactions during epithelial morphogenesis of internal organs. To address this issue we have developed the first time-lapse system to study vascularization of a mammalian organ in four dimensions. We show that vascularization of XX and XY Gonads is a highly dynamic, sexually dimorphic process. The XX Gonad recruits vasculature by a typical angiogenic process. In contrast, the XY Gonad recruits and patterns vasculature by a novel remodeling mechanism beginning with breakdown of an existing mesonephric vessel. Subsequently, in XY organs individual endothelial cells migrate and reaggregate in the coelomic domain to form the major testicular artery. Migrating endothelial cells respect domain boundaries well before they are morphologically evident, subdividing the Gonad into 10 avascular regions where testis cords form. This model of vascular development in an internal organ has a direct impact on the current dogma of vascular integration during organ development and presents important parallels with mechanisms of tumor vascularization.
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balancing the bipotential Gonad between alternative organ fates a new perspective on an old problem
Developmental Dynamics, 2006Co-Authors: Yuna Kim, Lanche CapelAbstract:The embryonic Gonads give rise to one of two morphologically and functionally different organs, a testis or an ovary. Sex determination is the embryonic process that determines the developmental fate of the Gonad. In mammals, sex determination is regulated by a DNA binding protein encoded on the Y chromosome, Sry, and it's downstream mediator, Sox9, which trigger testis determination in the bipotential Gonad. However, evidence suggests that the extracellular signals. Fgf9 and Wnt4, are also required to establish divergent organogenesis of the Gonad. In this review, we discuss how these extracellular signals interface with cell-autonomous factors to determine the fate of the mammalian Gonad, and we derive a model that could provide a molecular explanation for testis determination in vertebrates where Sry is absent.
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signaling at the crossroads of Gonad development
Trends in Endocrinology and Metabolism, 2005Co-Authors: Andrea J Ross, Lanche CapelAbstract:In mammals, the Gonads arise as bipotential primordia that are capable of developing as either testes or ovaries. Expression of the Y-linked gene Sry in the XY Gonad initiates testis differentiation; in the absence of Sry, ovarian pathways prevail. Although the molecular targets of SRY are not known, many of the early cellular and morphological events that occur downstream of Sry have been characterized. These include increased cell proliferation, Sertoli cell differentiation, testis cord formation, development of a testis-specific vasculature and differentiation of interstitial lineages. Recently, several of the molecular signals that direct these processes have been identified. In addition, the pathways that suppress features of testis development in the XX Gonad are being elucidated.
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cell proliferation is necessary for the determination of male fate in the Gonad
Developmental Biology, 2003Co-Authors: Jennife Schmahl, Lanche CapelAbstract:Cell proliferation has been shown to have multiple functions in development and pattern formation, including roles in growth, morphogenesis, and gene expression. Previously, we determined that the earliest known morphological event downstream of the male sex determining gene, Sry, is the induction of proliferation. In this study, we used proliferation inhibitors to block cell division during early Gonad development, at stages before the XY Gonad has committed to the testis pathway. Using the expression of sex-specific genes and the formation of testis morphology as markers of testis determination, we found that proliferation within a specific 8-h window was critical for the establishment of the male pathway and the formation of the testis. Inhibition of proliferation before or after this critical period led to smaller Gonads, but did not block testis formation. The critical period of proliferation coincides with the initiation of Sry expression and is essential for the differentiation of Sertoli cells, suggesting that proliferation is a vital component of the initiation of the male pathway by Sry. We believe these studies suggest that proliferation is involved not only in the elaboration of organ pattern, but also in the choice between patterns (male and female) in the bipotential Gonad.
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divergent vascular mechanisms downstream of sry establish the arterial system in the xy Gonad
Developmental Biology, 2002Co-Authors: Jennife Enna, Jeannie Karl, Lanche CapelAbstract:Although the primitive vasculature is identical in XX and XY genital ridges until 11.5 days postcoitum (dpc), by 12.5 dpc the XY Gonad develops a distinct vasculature. This male-specific vasculature, which includes the development of a large coelomic vessel, develops coincident with expression of Sry and formation of testis cords. We show that similar levels of proliferation and vasculogenesis expand the primary vasculature in XX and XY Gonads. However, soon after Sry expression begins, the XY Gonad recruits a large number of endothelial cells from the adjacent mesonephros, a mechanism totally absent in XX Gonads. These migrating cells do not contribute to venous or lymphatic development. Instead, these cells contribute to the arterial system, as indicated by expression of ephrinB2 and by elements of the Notch signaling pathway. This newly formed arterial system establishes a new pattern of blood flow in the XY Gonad, which we speculate may have an important role in export of testosterone to masculinize the XY embryo.
Margaux Noyon - One of the best experts on this subject based on the ideXlab platform.
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spatio temporal variation in effects of upwelling on the fatty acid composition of benthic filter feeders in the southern benguela ecosystem not all upwelling is equal
PLOS ONE, 2016Co-Authors: Eleonora Puccinelli, Christopher D Mcquaid, Margaux NoyonAbstract:Variability in mesoscale nearshore oceanographic conditions plays an important role in the distribution of primary production and food availability for intertidal consumers. Advection of nutrient rich waters by upwelling usually allows the proliferation of diatoms, later replaced by dinoflagellates. We examined upwelling effects on the fatty acid (FA) signature of a benthic intertidal filter feeder to identify its response to pulsed variability in food availability. The study took place in two contrasting seasons and at two upwelling and two non-upwelling sites interspersed within the southern Benguela upwelling system of South Africa. We investigated the FA composition of the adductor muscles and Gonads of the mussel Mytilus galloprovincialis to assess how FA are apportioned to the different tissues and whether this changes between upwelling and non-upwelling conditions. In situ temperature loggers used to identify upwelling conditions at the four sites indicated that such events occurred only at the upwelling centres and only in summer. Tissues differed strongly, with Gonads presenting a higher proportion of essential FAs. This could reflect the faster turnover rate of Gonad tissue or preferential retention of specific FA for reproductive purposes. FA composition did not vary as a direct function of upwelling, but there were strong dissimilarities among sites. Upwelling influenced mussel diets at one upwelling site while at the other, the expected signature of upwelling was displaced downstream of the core of upwelling. Condition Index (CI) and Gonad Index (GI) differed among sites and were not influenced by upwelling, with GI being comparable among sites. In addition, FA proportions were consistent among sites, indicating similar food quality and quantity over time and under upwelling and non-upwelling conditions. This suggests that the influence of upwelling on the west coast of South Africa is pervasive and diffuse, rather than discrete; while nearshore retention or advection of upwelled water is critical and site-specific so that the effects of upwelling differ even among sites categorised as upwelling centres.
Christopher M Pearce - One of the best experts on this subject based on the ideXlab platform.
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effect of urchin size and diet on Gonad yield and quality in the green sea urchin strongylocentrotus droebachiensis
Aquaculture, 2004Co-Authors: Christopher M Pearce, Tara L Dagge, Shaw M C RobinsoAbstract:Abstract A 6-week experiment (August 10 to September 21, 1999) was conducted to determine the effect of urchin size and diet on Gonad enhancement of the green sea urchin Strongylocentrotus droebachiensis. Sea urchins were collected from the wild and divided into four size classes—30.0–39.9, 40.0–49.9, 50.0–59.9, and 60.0–73.0 mm test diameter—each size group being split into two dietary treatments [prepared feed or kelp (Laminaria longicruris and/or Laminaria digitata)]. The experiment was a 4×2 completely crossed design. A number of Gonad attributes were quantified at the beginning and end of the experiment including: wet weight, percent yield, percent water, colour, texture, firmness, and taste. The percent change of these variables over the 6-week period was calculated. Colour was assessed subjectively by eye using colour ratings and objectively with a reflected-light, fibre-optic spectrophotometer to generate CIE L* (lightness), a* (hue), and b* (chroma) values. Gonad taste was subjectively evaluated at the end of the experiment. Results from experimental sea urchins were compared and contrasted with those of wild specimens collected from the source population at the end of the experiment. Percent Gonad yield at the end of the experiment and percent increase in percent Gonad yield over the 6-week period was significantly greater in urchins fed the prepared diet than in those fed kelp. Percent Gonad yield was highest in the 40.0–49.9 mm group, followed closely by the 50.0–59.9 and 30.0–39.9 mm size groups, whereas percent increase in percent Gonad yield decreased with increasing urchin size. Gonad colour at the end of the experiment was significantly better in urchins fed the prepared diet than in those fed kelp (as judged by colour ratings, a*, and b*) and was better in smaller than larger individuals (as judged by colour ratings, L*, and a*). Percent change in Gonad colour ratings decreased and percent change in L* and a* increased with increasing urchin size. Urchin size and feed type had no significant effect on Gonad texture, but both factors significantly influenced Gonad firmness and taste. Gonads of urchins fed the prepared diet were significantly softer and had significantly more water than those fed kelp. Gonad firmness and percent change in firmness increased with increasing urchin size. Kelp-fed individuals produced significantly better tasting Gonads than those fed the prepared diet. The largest urchins produced the best tasting Gonads of those fed kelp, but the smallest individuals had the best Gonad taste of those fed the prepared diet. Overall, considering both Gonad quantity and quality factors, sea urchins of 40.0–49.9 mm test size were deemed to be the most promising for Gonad enhancement operations.
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effect of protein source ratio and protein concentration in prepared diets on Gonad yield and quality of the green sea urchin strongylocentrotus droebachiensis
Aquaculture, 2002Co-Authors: Christopher M Pearce, Tara L Daggett, Shawn M C RobinsonAbstract:Adult green sea urchins (Strongylocentrotus droebachiensis) were collected from the wild and held in laboratory tanks where they were fed a number of prepared diets or a control of kelp (Laminaria longicruris and/or L. digitata) for a period of 12 weeks. Twelve different prepared diets were formulated in order to examine two experimental factors: (1) protein concentration at three different levels [19%, 24%, and 29% (percent dry weight of all dietary components)] and (2) protein source ratio at four different levels [rockweed meal, wheat meal, corn meal, soybean meal, fish meal in the following four ratios: 0:30:30:25:15, 15:20:20:35:10, 30:10:10:45:5, 45:0:0:55:0, respectively (percent dry weight of all meals)]. Each concentration was present at each source ratio in a completely crossed experimental design. Gonad colour, percent Gonad water, and percent Gonad yield of experimental urchins were determined approximately every week while Gonad texture, firmness, and taste were subjectively evaluated at the end of the experiment. Results were contrasted with those of wild specimens collected from the source population at weeks 0 and 12 of the experiment. After 12 weeks, all prepared diets produced significantly higher percent Gonad yields than kelp-fed urchins or wild controls, the best-prepared diet giving a mean weekly increase of 1.3% in percent yield. Percent Gonad yield was not significantly affected by protein concentration, but was significantly affected by protein source ratio; the 15:20:20:35:10 diet gave significantly higher yields than the 0:30:30:25:15 or 45:0:0:55:0 diets (30:10:10:45:5 being intermediate). Gonad colour of urchins fed prepared diets was, generally, pale yellow/orange to yellow-brown/orange-brown at the end of the experiment and not significantly different from kelp-fed urchins or wild controls. Gonad colour was not significantly affected by protein source ratio, but was significantly affected by protein concentration; the 19% and 24% levels produced significantly better coloured Gonads than the 29% level. At the end of the experiment, Gonad texture of urchins fed prepared diets ranged from smooth to very smooth with distinct Gonad segment halves while Gonad firmness ranged from firm to very firm. Gonad texture and firmness of prepared diet treatments did not differ significantly from kelp-fed urchins or wild controls and neither protein concentration nor protein source ratio significantly affected Gonad texture or firmness. At the end of the experiment, Gonad taste of urchins fed prepared diets ranged from bitter to sweet with all prepared diets producing significantly worse tasting Gonads than the kelp-fed urchins. Gonad taste was not significantly affected by protein source ratio nor protein concentration, but there was a general trend of worsening taste with increasing protein levels. Based on these results, a 19% protein concentration and a 15:20:20:35:10 (rockweed meal/wheat meal/corn meal/soybean meal/fish meal) protein source ratio are recommended for further dietary research.
Shaw M C Robinso - One of the best experts on this subject based on the ideXlab platform.
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effect of urchin size and diet on Gonad yield and quality in the green sea urchin strongylocentrotus droebachiensis
Aquaculture, 2004Co-Authors: Christopher M Pearce, Tara L Dagge, Shaw M C RobinsoAbstract:Abstract A 6-week experiment (August 10 to September 21, 1999) was conducted to determine the effect of urchin size and diet on Gonad enhancement of the green sea urchin Strongylocentrotus droebachiensis. Sea urchins were collected from the wild and divided into four size classes—30.0–39.9, 40.0–49.9, 50.0–59.9, and 60.0–73.0 mm test diameter—each size group being split into two dietary treatments [prepared feed or kelp (Laminaria longicruris and/or Laminaria digitata)]. The experiment was a 4×2 completely crossed design. A number of Gonad attributes were quantified at the beginning and end of the experiment including: wet weight, percent yield, percent water, colour, texture, firmness, and taste. The percent change of these variables over the 6-week period was calculated. Colour was assessed subjectively by eye using colour ratings and objectively with a reflected-light, fibre-optic spectrophotometer to generate CIE L* (lightness), a* (hue), and b* (chroma) values. Gonad taste was subjectively evaluated at the end of the experiment. Results from experimental sea urchins were compared and contrasted with those of wild specimens collected from the source population at the end of the experiment. Percent Gonad yield at the end of the experiment and percent increase in percent Gonad yield over the 6-week period was significantly greater in urchins fed the prepared diet than in those fed kelp. Percent Gonad yield was highest in the 40.0–49.9 mm group, followed closely by the 50.0–59.9 and 30.0–39.9 mm size groups, whereas percent increase in percent Gonad yield decreased with increasing urchin size. Gonad colour at the end of the experiment was significantly better in urchins fed the prepared diet than in those fed kelp (as judged by colour ratings, a*, and b*) and was better in smaller than larger individuals (as judged by colour ratings, L*, and a*). Percent change in Gonad colour ratings decreased and percent change in L* and a* increased with increasing urchin size. Urchin size and feed type had no significant effect on Gonad texture, but both factors significantly influenced Gonad firmness and taste. Gonads of urchins fed the prepared diet were significantly softer and had significantly more water than those fed kelp. Gonad firmness and percent change in firmness increased with increasing urchin size. Kelp-fed individuals produced significantly better tasting Gonads than those fed the prepared diet. The largest urchins produced the best tasting Gonads of those fed kelp, but the smallest individuals had the best Gonad taste of those fed the prepared diet. Overall, considering both Gonad quantity and quality factors, sea urchins of 40.0–49.9 mm test size were deemed to be the most promising for Gonad enhancement operations.
Ami Enamotz - One of the best experts on this subject based on the ideXlab platform.
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improving Gonad colour and somatic index in the european sea urchin paracentrotus lividus
Aquaculture, 2005Co-Authors: Muki Shpigel, Susa C Mcbride, Sharo Marciano, Ami EnamotzAbstract:Abstract One of the major factors influencing marketability of sea urchins is their Gonad colour. The effects of a prepared diet, algal diets, and rotational feeding of these diet treatments on the European sea urchin Paracentrotus lividus were studied to determine a diet that would provide optimal Gonad colour and Gonadal somatic index (GSI). P. lividus underwent six diet treatments: Ulva lactuca and Gracilaria conferta for 12 weeks (UG-12); prepared diet for 10 weeks followed by administration of Ulva and Gracilaria for 2 weeks (P-10); prepared diet for 8 weeks followed by Ulva and Gracilaria for 4 weeks (P-8); prepared diet for 6 weeks followed by Ulva and Gracilaria for 6 weeks (P-6); prepared diet for 12 weeks (P-12); and Ulva , Gracilaria and prepared diet for 12 weeks (UGP-12). The algae diet produced a dark orange colour but a low GSI. The pellet diet produced a good GSI but pale Gonad colour. P. lividus fed the prepared diet for 8 weeks followed by 4 weeks of algal diet produced the optimal combination of desired Gonad colour and GSI. The dominant carotenoid in the Gonads was echinenone, which the sea urchin synthesises from β-carotene. The higher the echinenone level in the Gonads, the more intense their colouration. The lack of echinenone found in the gut and its high accumulation in the Gonad, in inverse proportion to the β-carotene profile, indicates bioconversion within the Gonad or upon transfer from the gut to the Gonad.