Reproductive biology of the freshwater catfish, Tandanus tandanus Mitchell, in the Gwydir River, Australia. I. Structure of the gonads

1977 ◽  
Vol 28 (2) ◽  
pp. 139 ◽  
Author(s):  
TLO Davis
Keyword(s):  
Reproductive Biology ◽  
Oocyte Maturation ◽  
Reproductive Cycle ◽  
Germ Cells ◽  
Complicated Structure ◽  
Histological Changes ◽  
Macroscopic Appearance ◽  
Freshwater Catfish ◽  
Clear Cut ◽  
The Relationship

The gross morphology and histology of the gonads of T. tandanus were examined as a preliminary to describing the reproductive cycle of this species in the Gwydir River. The macroscopic appearance of the gonads at different stages of maturity is described. The complicated structure of the testes made it difficult to classify them into well-defined stages of maturity. The relationship between the stage of maturity of the ovaries and the histological changes associated with oocyte maturation was clear cut. Six spermatogenetic stages were recognized; primary germ cells, spermatogonia, primary spermatocytes, secondary spermatocytes, spermatids, and spermatozoa. The sequence of oocyte maturation was divided into nine stages; chromatin nucleolus, early perinucleolus, late perinucleolus, yolk vesicle, primary yolk, secondary yolk, tertiary yolk, and ripe egg stage. Atresia was observed in some oocytes from the primary yolk stage onwards. The sequence of yolk resorption in atretic oocytes is described.

scholarly journals Reproductive biology of the dusky grouper Epinephelus marginatus (Lowe, 1834)

2003 ◽  
Vol 46 (3) ◽  
pp. 373-382 ◽  
Author(s):  
Áthila Bertoncini Andrade ◽  
Leonardo Francisco Machado ◽  
Maurício Hostim-Silva ◽  
João Pedro Barreiros
Keyword(s):  
Reproductive Biology ◽  
Marine Reserve ◽  
Spawning Season ◽  
Spawning Activity ◽  
Histological Changes ◽  
Dusky Grouper ◽  
Post Spawning ◽  
The Relationship ◽  
Rocky Bottoms ◽  
Intertidal Pools

Investigations were carried out about the reproductive biology of the dusky grouper, Epinephelus marginatus (Lowe, 1834) a serranid protogynous hermaphrodite fish inhabitant of rocky bottoms from shallow waters up to 200 m depth. Samples were caught in the islands that form Arvoredo Biological Marine Reserve (SC - Brazil) and the coastal islands near Florianópolis region from March 1998 to May 2000. Data from samples of juvenile groupers on intertidal pools were used to link their occurrence in the pools to the post-spawning season. To describe the histological changes on gonads along the reproductive cycle and to establish maturation scales, 109 groupers were histologically tested for sex determination. First maturation size was determined for females (L50=470 mm; r²=0.99). The results of calculated gonadosomatic (GSI) and hepatosomatic (HSI) indexes, showed that maturation occurred along the spring months and the spawning activity during the summer with a peak in December. Liver recovery (HSI elevation) was evident in the autumn, was the post spawning season. The relationship between length and weight was W = 9 · 10-6 · TL3.1149 (r²=0.998; n=246).

Reproductive biology and endocrinology of greenback flounder Rhombosolea tapirina (GÜnther 1862)

1999 ◽  
Vol 50 (1) ◽  
pp. 35 ◽  
Author(s):  
C. W. Barnett ◽  
N. W. Pankhurst
Keyword(s):  
Reproductive Biology ◽  
Oocyte Maturation ◽  
Plasma Concentrations ◽  
Reproductive Development ◽  
Gonadal Development ◽  
Oocyte Development ◽  
Oocyte Size ◽  
Frequency Distributions ◽  
Final Oocyte Maturation ◽  
The Relationship

The relationship between patterns of gonadal development and endocrine changes during reproductive development was examined in the greenback flounder (Rhombosolea tapirina). Oocyte size–frequency distributions showed that female greenback flounder have group synchronous oocyte development, and that there are multiple ovulations. Plasma and ovarian concentrations of testosterone (T) and 17β-oestradiol (E2) were elevated in association with vitellogenesis. Plasma concentrations of 17,20β-dihydroxy-4-pregnen-3-one (17,20βP) were significantly elevated in ovulated females, whereas ovarian concentrations of 17,20βP were elevated in association with final oocyte maturation (FOM) and ovulation. Plasma concentrations of 17,20βP-sulfate but not 17,20βP-glucuronide were elevated in association with FOM and ovulation. Changes in macroscopic testis stage were not accompanied by significant changes in proportions of gamete types in the testis. Plasma concentrations of T were elevated in spermatogenic and partially spermiated males. No significant changes in plasma 11-ketotestosterone (11KT), 17,20βP, 17,20βP-sulfate and 17,20βP-glucuronide were detected with change in testis stage.

scholarly journals From reflex to reflection: Moving from the space of causes to the space of reasons and back

2020 ◽  
Vol 3 (1) ◽  
pp. 681-693
Author(s):  
Ariel Furstenberg
Keyword(s):  
The Other ◽  
Final Part ◽  
Clear Cut ◽  
Other Hand ◽  
Space Of Reasons ◽  
The One ◽  
The Relationship ◽  
Simple Picture

AbstractThis article proposes to narrow the gap between the space of reasons and the space of causes. By articulating the standard phenomenology of reasons and causes, we investigate the cases in which the clear-cut divide between reasons and causes starts to break down. Thus, substituting the simple picture of the relationship between the space of reasons and the space of causes with an inverted and complex one, in which reasons can have a causal-like phenomenology and causes can have a reason-like phenomenology. This is attained by focusing on “swift reasoned actions” on the one hand, and on “causal noisy brain mechanisms” on the other hand. In the final part of the article, I show how an analogous move, that of narrowing the gap between one’s normative framework and the space of reasons, can be seen as an extension of narrowing the gap between the space of causes and the space of reasons.

scholarly journals sCD14 Level in Saliva of Children and Adolescents with and without Dental Caries, a Hurdle Model

Children ◽  
2021 ◽  
Vol 8 (8) ◽  
pp. 679
Author(s):  
Gaia Pellegrini ◽  
Marcello Maddalone ◽  
Matteo Malvezzi ◽  
Marilisa Toma ◽  
Massimo Del Fabbro ◽  
...  
Keyword(s):  
Dental Caries ◽  
Innate Immune ◽  
Hurdle Model ◽  
Soluble Cd14 ◽  
Clear Cut ◽  
Carious Lesions ◽  
Decayed Tooth ◽  
Group A ◽  
The Relationship ◽  
Control Study

Objective: Soluble CD14 (sCD14) plays an important role in the innate immune response of the oral cavity. The investigation of this biomarker for detection of carious lesions is an even more actual procedure due to its non-invasiveness and the ease of withdrawal. The purpose of the present observational case-control study was to evaluate whether the quantification of sCD14 in children and adolescent’s saliva can discriminate healthy subjects from those suffering from tooth decay. Materials and Methods: 164 subjects (6 to 17 years) were selected and divided into 2 groups: those with at least 1 decayed tooth were assigned to group Decayed (n = 82) and those free from dental caries to group Healthy (n = 82). The amount of salivary soluble CD14 was quantified. Results: Mean salivary soluble CD14 was 28.3 ± 10.8 μg/mL in the Healthy group and 22 ± 9.6 μg/mL in the Decayed group. A hurdle model was applied to the data to estimate both the probability of having carious lesions and their number in relation to sCD14 levels. sCD14 was strongly associated (p < 0.01) with an inverse relation to both the probability of having caries and their number (falling rate of 5% per unit CD14 μg/mL). Conclusions: This data confirms the relationship between sCD14 and the presence of dental caries. However, there is no clear cut off level between healthy and unhealthy subjects, so it is currently not possible to use sCD14 as a biomarker to determine the risk of decays.

scholarly journals Persistent Activist Communication in Occupy Gezi

Sociology ◽  
2017 ◽  
Vol 52 (5) ◽  
pp. 915-933 ◽  
Author(s):  
Dan Mercea ◽  
Duygu Karatas ◽  
Marco T Bastos
Keyword(s):  
Survey Data ◽  
Early Summer ◽  
Online Activity ◽  
Clear Cut ◽  
Twitter Data ◽  
Organisational Structures ◽  
Biographical Availability ◽  
Event Based ◽  
The Relationship ◽  
Depth Interviews

We revisit the notion of activist persistence against the backdrop of protest communication on Twitter. We take an event-based approach and examine Occupy Gezi, a series of protests that occurred in Turkey in the early summer of 2013. By cross-referencing survey data with longitudinal Twitter data and in-depth interviews, we investigate the relationship between biographical availability, relational and organisational ties, and social and personal costs to persistent activism online and on location. Contrary to expectations, we find no clear-cut relationship between those factors and sustained commitment to participation in the occupation. We show that persistent activist communication did not feed into enduring organisational structures despite the continuous online activity observed during and beyond the peak of the Gezi occupation. The article concludes with reflections on the organisational ramifications of persistent communication and its significance in a political context posing high risks to participation in dissident politics.

Antitumor effects of antiprogesterones on human meningioma cells in vitro and in vivo

1994 ◽  
Vol 80 (3) ◽  
pp. 527-534 ◽  
Author(s):  
Yasuhiro Matsuda ◽  
Keiichi Kawamoto ◽  
Katsuzo Kiya ◽  
Kaoru Kurisu ◽  
Kazuhiko Sugiyama ◽  
...  
Keyword(s):  
Marked Reduction ◽  
Tumor Volume ◽  
Collagen Gel ◽  
Antitumor Effects ◽  
Histological Changes ◽  
Content Type ◽  
The Relationship ◽  
Fine Print

✓ The presence of the progesterone receptor (PR) in meningioma tissue has been confirmed by previous investigations. Studies have shown that the antiprogesterone drug, mifepristone, is a potent agent that inhibits the growth of cultured meningioma cells and reduces the size of meningiomas in experimental animal models and humans. However, these studies have not fully examined the relationship between the antitumor effects of an antiprogesterone agent and the expression of the PR. The present study examined the antitumor effects of mifepristone and a new potent antiprogesterone agent, onapristone; a correlation between the antitumor effects of these antiprogesterones and the presence of PR's in meningiomas in vitro and in vivo was also investigated. Meningioma tissue surgically removed from 13 patients was used in this study. In the in vitro arm of the study, mifepristone and onapristone exhibited cytostatic and cytocidal effects against cultured meningioma cells, regardless of the presence or absence of PR's; however, three PR-negative meningiomas showed no response to any dose of mifepristone and/or onapristone. In the in vivo arm, meningioma cells, embedded in a collagen gel, were implanted into the renal capsules of nude mice. Antiprogesterone treatment resulted in a marked reduction of the tumor volume regardless of the presence or absence of PR's. No histological changes in the meningioma cells suggestive of necrosis or apoptosis were detected in any of the mice treated with antiprogesterones. These findings suggest that mifepristone and onapristone have an antitumor effect against meningioma cells via the PR's and/or another receptor, such as the glucocorticoid receptor.

scholarly journals Distribution and reproductive biology of the Electric ray Discopyge tschudii Heckel, 1846 in San Matías Gulf, Northern Patagonia, Argentina

2011 ◽  
Vol 9 (4) ◽  
pp. 831-838 ◽  
Author(s):  
Marilú Estalles ◽  
Nidia Marina Coller ◽  
Edgardo Ernesto Di Giácomo ◽  
María Raquel Perier
Keyword(s):  
Sexual Dimorphism ◽  
Reproductive Biology ◽  
Reproductive Cycle ◽  
Southern Chile ◽  
Southern Brazil ◽  
Southwest Atlantic ◽  
Aggregate Distribution ◽  
Northern Patagonia ◽  
Southeast Pacific ◽  
Discopyge Tschudii

The Electric ray Discopyge tschudii is distributed in the Southwest Atlantic from southern Brazil to southern Argentina and in the Southeast Pacific from Peru to southern Chile. The main threat to this species is fishing. Discopyge tschudii is noncommercial and individuals caught are discarded on board. The present study analyzes the distribution and the morphological and reproductive characteristics of this ray in San Matías Gulf (SMG), Argentina. A total of 1087 individuals were analyzed. The species presented an aggregate distribution, with the main concentrations in the northern and eastern areas of SMG, at depths below 100 m. Males ranged from 9 to 43 cm and females from 11 to 38 cm. The species presented sexual dimorphism. Males were larger and heavier than females and also matured at larger sizes. Size at 50% of maturity was estimated at 30 cm for males and 21 cm for females. A total of 199 embryos were sampled and the proportion of sexes showed no significant differences from the expected 1:1. The number of embryos per female varied from 1 to 12. The most frequent values were 2 and 5. Length at birth was estimated at 82.17 ± 3.87 mm. Based on our findings, we hypothesize that the electric ray D. tschudii completes its reproductive cycle in SMG.

Gentrification, displacement and the arts: Untangling the relationship between arts industries and place change

Urban Studies ◽  
2016 ◽  
Vol 55 (4) ◽  
pp. 807-825 ◽  
Author(s):  
Carl Grodach ◽  
Nicole Foster ◽  
James Murdoch
Keyword(s):  
Urban Policy ◽  
Statistical Study ◽  
Change Agents ◽  
Creative Industries ◽  
Standard Account ◽  
Clear Cut ◽  
The Arts ◽  
Neighbourhood Level ◽  
The Relationship

The arts have long played a role in debates around gentrification and displacement, yet their roles and impacts as change agents are not clear-cut. According to the standard account, artists facilitate gentrification and ultimately engender the displacement of lower income households, but more recent research complicates the accepted narrative. This article seeks to untangle the relationship between the arts, gentrification and displacement through a statistical study of neighbourhood-level arts industry activity within large US regions. The findings indicate that the standard arts-led gentrification narrative is too generalised or simply no longer applicable to contemporary arts-gentrification processes. Rather, the arts have multiple, even conflicting relationships with gentrification and displacement that depend on context and type of art. These results have important implications for how we study the role of the arts in neighbourhood change and for how governments approach the arts and creative industries in urban policy.

scholarly journals An evolutionary process without variation and selection

2021 ◽  
Vol 18 (180) ◽  
pp. 20210334
Author(s):  
Liane Gabora ◽  
Mike Steel
Keyword(s):  
Germ Cells ◽  
Cultural Evolution ◽  
Self Assembly ◽  
Early Life ◽  
Evolutionary Process ◽  
Adaptive Change ◽  
Assembly Code ◽  
The Relationship ◽  
Special Case ◽  
Variation And Selection

Natural selection successfully explains how organisms accumulate adaptive change despite that traits acquired over a lifetime are eliminated at the end of each generation. However, in some domains that exhibit cumulative, adaptive change—e.g. cultural evolution, and earliest life—acquired traits are retained; these domains do not face the problem that Darwin’s theory was designed to solve. Lack of transmission of acquired traits occurs when germ cells are protected from environmental change, due to a self-assembly code used in two distinct ways: (i) actively interpreted during development to generate a soma, and (ii) passively copied without interpretation during reproduction to generate germ cells. Early life and cultural evolution appear not to involve a self-assembly code used in these two ways. We suggest that cumulative, adaptive change in these domains is due to a lower-fidelity evolutionary process, and model it using reflexively autocatalytic and foodset-generated networks. We refer to this more primitive evolutionary process as self–other reorganization (SOR) because it involves internal self-organizing and self-maintaining processes within entities, as well as interaction between entities. SOR encompasses learning but in general operates across groups. We discuss the relationship between SOR and Lamarckism, and illustrate a special case of SOR without variation.

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