Asymmetry in hormone biosynthesis by insect endocrine glands

1977 ◽  
Vol 55 (9) ◽  
pp. 1509-1514 ◽  
Author(s):  
Stephen S. Tobe
Keyword(s):  
Schistocerca Gregaria ◽  
Adult Life ◽  
Relative Activity ◽  
Corpora Allata ◽  
Endocrine Function ◽  
Endocrine Glands ◽  
Hormone Biosynthesis ◽  
Left And Right ◽  
Absolute Quantity ◽  
The Brain

The corpora allata (CA) of the desert locust Schistocerca gregaria are paired endocrine glands known to synthesize juvenile hormone (JH). The ability of individual members of the pair to synthesize JH has been examined between days 7 and 14 of adult life. Left and right glands in an individual animal can make different quantities of JH (up to 1000: 1), indicating that it cannot be assumed that endocrine glands in any given animal are of equal endocrinological activity. This asymmetry in endocrine function appears to be randomly distributed and thus the relative activity of members of the pair cannot be predicted. The asymmetry does not appear to be related to either the total quantity of JH synthesized or to the age of the animals. It is significant that no matter which member of the pair is more active, the absolute quantity of hormone synthesized by the CA of different animals of the same age is similar. The factors which regulate the endocrine asymmetry are not known but feedback loops between the brain and CA are implied. The functional significance of asymmetry may be related to a cyclical alternation in synthesis of JH by the members of the pair.

scholarly journals The influence of substrate concentrations on the rate of insect juvenile hormone biosynthesis by corpora allata of the desert locust in vitro

1974 ◽  
Vol 144 (1) ◽  
pp. 107-113 ◽  
Author(s):  
Stephen S. Tobe ◽  
Grahame E. Pratt
Keyword(s):  
Juvenile Hormone ◽  
Schistocerca Gregaria ◽  
Corpora Allata ◽  
Synthetic Activity ◽  
Methyl Farnesoate ◽  
Physiological Concentration ◽  
Juvenile Hormone Biosynthesis ◽  
Hormone Biosynthesis ◽  
Influence Of Substrate

The rate at which isolated corpora allata of adult female Schistocerca gregaria incorporate [3H]farnesenic acid and [14C]methionine into C16juvenile hormone in vitro was examined at different concentrations of farnesenic acid, methionine, O2 and H+ ions. Maximum juvenile hormone biosynthesis is obtained at a farnesenic acid concentration of 20μm. The range of optimum l-methionine concentrations (0.1–0.4mm) encompasses the physiological concentration of this substrate in the haemolymph. Hormone biosynthesis is dependent on O2, but is not stimulated by hyperbaric oxygen tension. The glands had a maximum synthetic activity at pH8.0, but their activity was more reproducible in the the physiological range pH7.0–7.5. At pH6.5 and less, the synthetic ability was considerably decreased. The relative incorporations of the labelled substrates into methyl farnesoate and C16 juvenile hormone indicate that [3H]farnesenic acid comes into isotopic equilibrium within the gland more rapidly than [14C]methionine. The incorporations into methyl farnesoate become stoicheiometric after 20min incubation and into C16 juvenile hormone after a further 10min. Labelled juvenile hormone is detectable after 10min incubation and the rate of incorporation is constant for up to 4h. It is proposed that the described method may be usefully employed to assess the physiological changes in the enzymic competence of the glands to effect the last two stages in C16 juvenile hormone biosynthesis.

Juvenile hormone biosynthesis by the corpora allata of the male desert locust, Schistocerca gregaria, during sexual maturation

1978 ◽  
Vol 56 (10) ◽  
pp. 2097-2102 ◽  
Author(s):  
L. I. Avruch ◽  
S. S. Tobe
Keyword(s):  
Juvenile Hormone ◽  
Sexual Maturation ◽  
Time Course ◽  
Schistocerca Gregaria ◽  
Dry Weight ◽  
Corpora Allata ◽  
Gas Liquid Chromatography ◽  
Juvenile Hormone Biosynthesis ◽  
Hormone Biosynthesis

The time course of release of C16 juvenile hormone (JH III) from isolated corpora allata (CA) of male Schistocerca gregaria was followed at selected times during sexual maturation. The rates of JH release over an 8-h incubation period were observed to be directly related to the age of the animals: CA from younger animals showed low rates of release (days 5 and 8) whereas CA from older animals showed intermediate to high rates of release (days 12–13). The mean rate of JH release is linear for at least 4 h. The only biosynthesized JH which could be detected in the incubation medium by radio gas–liquid chromatography was C16JH.The dry weight of the accessory reproductive glands (ARG) was also followed during the period of sexual maturation. This increased rapidly between days 10 and 15 and leveled off thereafter. The biosynthesis of C16JH, as determined by a radiochemical assay in vitro, also increased during this period, suggesting a functional relationship between synthesis of ARG secretion and JH.

Morphology and histology of the cephalic endocrine glands of the damselfly, Coenagrion angulatum Walker (Zygoptera: Odonata)

1969 ◽  
Vol 47 (6) ◽  
pp. 1187-1192
Author(s):  
C. Gillott
Keyword(s):  
Sexual Maturation ◽  
Adult Life ◽  
Secretory Activity ◽  
Neurosecretory Cells ◽  
Corpora Allata ◽  
Single Pair ◽  
General Shape ◽  
Corpora Cardiaca ◽  
Ventral Glands ◽  
The Brain

In Coenagrion angulatum Walk. there is a single group of neurosecretory cells, median in position, on each side of the brain. The A- and B-type cells are intermingled within each group and their axons form a single pair of nerves to the corpora cardiaca. No pattern of secretory activity is discernible in the B cells. The A cells of mature nymphs and newly emerged adults are loaded with fuchsinophilic droplets but the amount of stainable material decreases as sexual maturation proceeds. A corresponding change in the location and amount of fuchsinophilic material takes place in the corpora cardiaca. In the mature nymph and young adult there is much material distributed throughout the gland. During sexual maturation it becomes less in quantity and restricted to a position adjacent to the aorta wall. A pair of stout, strongly fuchsinophilic nerves leaves the anterior end of the corpora cardiaca and passes ventrolaterally. These bypass the corpora allata and enter the thorax. Their point of termination has not been determined in this study. The corpora allata are small, roundish-oval bodies in the mature juvenile and newly emerged adult damselfly. While retaining their general shape they increase in volume several fold as sexual maturation takes place. The ventral glands are large, lobular structures in mature nymphs. Immediately after emergence they shrink and their cells become pycnotic. Generally by the fourth day of adult life they have disappeared. The results of this study are discussed in relation to those of other authors for the Odonata.

Advantages of Complementary Stereo Images as Viewed with the Low-Temperature Field-Emission SEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1314-1315
Author(s):  
William P. Wergin ◽  
Eric F. Erbe
Keyword(s):  
Fold Increase ◽  
Horizontal Displacement ◽  
Three Dimensions ◽  
Stereo Image ◽  
Stereo Pair ◽  
Sem Micrograph ◽  
Left And Right ◽  
The Common ◽  
The Brain ◽  
Pair Analysis

The eye-brain complex allows those of us with normal vision to perceive and evaluate our surroundings in three-dimensions (3-D). The principle factor that makes this possible is parallax - the horizontal displacement of objects that results from the independent views that the left and right eyes detect and simultaneously transmit to the brain for superimposition. The common SEM micrograph is a 2-D representation of a 3-D specimen. Depriving the brain of the 3-D view can lead to erroneous conclusions about the relative sizes, positions and convergence of structures within a specimen. In addition, Walter has suggested that the stereo image contains information equivalent to a two-fold increase in magnification over that found in a 2-D image. Because of these factors, stereo pair analysis should be routinely employed when studying specimens.Imaging complementary faces of a fractured specimen is a second method by which the topography of a specimen can be more accurately evaluated.

scholarly journals Evaluation of the BDNF, NGF, NT3 and NT4 Genes Expressions in the Brains of Neonatal Mice with Hypothyroidism

2017 ◽  
Vol 7 (1) ◽  
pp. 171
Author(s):  
Hamid Reza Adeli Bhroz ◽  
Kazem Parivar ◽  
Iraj Amiri ◽  
Nasim Hayati Roodbari
Keyword(s):  
Dose Group ◽  
Low Dose ◽  
Pure Water ◽  
Intervention Group ◽  
Control Group ◽  
High Dose ◽  
Endocrine Glands ◽  
Blood Samples ◽  
High Doses ◽  
The Brain

Background and Aim: Thyroid is one of the endocrine glands, (T3 and T4) play a significant role in the development of prenatal brain and the following stages. The study aimed to evaluate the effect of hypothyroidism on the amount of expression of NT4, NT3, nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) in brain of one-day rat neonates with hypothyroidism.Materials and Methods: In total, 25 mature mice of Albino NMRI race were selected after mating, divided into three group, control, as well as low-dose and high-dose intervention groups. Samples of the control group received pure water during pregnancy, whereas subjects of the intervention group with low and high doses of the medication were administered with 20 mg and 100 mg methimazole powder (dissolved in 100 cc water), respectively. After child delivery, blood samples were obtained from mother mice to determine the level of T3 and T4 in blood serum. Following that, the brain of one-day mice were removed by surgery and assessed to determine the amount of expression of NT4, NT3, NGF and BDNF using the complete kit of RT-PCR.Results: Levels of T4 and T3 in the control group were 28 ug/dl and 1.59 ug/dl, respectively. In the low-dose intervention group, the amounts of the mentioned hormones were 8 ug/dl and 0.85 ug/dl, significantly, indicating a significant reduction in the expression of NT4, NT3, NGF and BDNF genes, compared to the control group. Moreover, T4 and T3 were 6 ug/dl and 0.79 ug/dl in the high-dose group, respectively, conveying a significant decrease in the expression of NT4, NT3, NGF and BDNF genes, compared to the control group (P<0.05).

scholarly journals The Hammer and the Nail: Biomechanics of Striking and Struck Canadian University Football Players

2021 ◽  
Author(s):  
Jeffrey S. Brooks ◽  
Adam Redgrift ◽  
Allen A. Champagne ◽  
James P. Dickey
Keyword(s):  
College Football ◽  
Head Impact ◽  
Football Players ◽  
Video Footage ◽  
Impact Location ◽  
Rule Changes ◽  
Left And Right ◽  
The Brain

AbstractThis study sought to evaluate head accelerations in both players involved in a football collision. Players on two opposing Canadian university teams were equipped with helmet mounted sensors during one game per season, for two consecutive seasons. A total of 276 collisions between 58 instrumented players were identified via video and cross-referenced with sensor timestamps. Player involvement (striking and struck), impact type (block or tackle), head impact location (front, back, left and right), and play type were recorded from video footage. While struck players did not experience significantly different linear or rotational accelerations between any play types, striking players had the highest linear and rotational head accelerations during kickoff plays (p ≤ .03). Striking players also experienced greater linear and rotational head accelerations than struck players during kickoff plays (p = .001). However, struck players experienced greater linear and rotational accelerations than striking players during kick return plays (p ≤ .008). Other studies have established that the more severe the head impact, the greater risk for injury to the brain. This paper’s results highlight that kickoff play rule changes, as implemented in American college football, would decrease head impact exposure of Canadian university football athletes and make the game safer.

scholarly journals Update on angiotensin II: new endocrine connections between the brain, adrenal glands and the cardiovascular system

2017 ◽  
Vol 6 (7) ◽  
pp. R131-R145 ◽  
Author(s):  
Frans H H Leenen ◽  
Mordecai P Blaustein ◽  
John M Hamlyn
Keyword(s):  
Angiotensin Ii ◽  
Sympathetic Activity ◽  
Endocrine Function ◽  
Lv Function ◽  
Slow Pathway ◽  
Ang Ii ◽  
Endogenous Ouabain ◽  
Plasma Angiotensin ◽  
Synthase Inhibitor ◽  
The Brain

In the brain, angiotensinergic pathways play a major role in chronic regulation of cardiovascular and electrolyte homeostasis. Increases in plasma angiotensin II (Ang II), aldosterone, [Na+] and cytokines can directly activate these pathways. Chronically, these stimuli also activate a slow neuromodulatory pathway involving local aldosterone, mineralocorticoid receptors (MRs), epithelial sodium channels and endogenous ouabain (EO). This pathway increases AT1R and NADPH oxidase subunits and maintains/further increases the activity of angiotensinergic pathways. These brain pathways not only increase the setpoint of sympathetic activity per se, but also enhance its effectiveness by increasing plasma EO and EO-dependent reprogramming of arterial and cardiac function. Blockade of any step in this slow pathway or of AT1R prevents Ang II-, aldosterone- or salt and renal injury-induced forms of hypertension. MR/AT1R activation in the CNS also contributes to the activation of sympathetic activity, the circulatory and cardiac RAAS and increase in circulating cytokines in HF post MI. Chronic central infusion of an aldosterone synthase inhibitor, MR blocker or AT1R blocker prevents a major part of the structural remodeling of the heart and the decrease in LV function post MI, indicating that MR activation in the CNS post MI depends on aldosterone, locally produced in the CNS. Thus, Ang II, aldosterone and EO are not simply circulating hormones that act on the CNS but rather they are also paracrine neurohormones, locally produced in the CNS, that exert powerful effects in key CNS pathways involved in the long-term control of sympathetic and neuro-endocrine function and cardiovascular homeostasis.

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