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31.
32.
Hormones are critical for the development, maturation, and maintenance of physiological systems; therefore, understanding their involvement during maturation of the brain is important for the elucidation of mechanisms by which adults become behaviorally competent. Changes in exogenous and endogenous factors encountered during sexual maturation can have long lasting effects in mature adults. In this study, we investigated the role of the gonadotropic hormone, juvenile hormone (JH), in the modulation of adult behaviors in Drosophila. Here we utilized methoprene (a synthetic JH analog) and precocene (a JH synthesis inhibitor) to manipulate levels of JH in sexually immature male and female Drosophila with or without decreased synthesis of neuronal dopamine (DA). Locomotion and courtship behavior were assayed once the animals had grown to sexual maturity. The results demonstrate a sexually dimorphic role for JH in the modulation of these centrally controlled behaviors in mature animals that is dependent on the age of the animals assayed, and present DA as a candidate neuronal factor that differentially interacts with JH depending on the sex of the animal. The data also suggest that JH modulates these behaviors through an indirect mechanism. Since gonadotropic hormones and DA interact in mammals to affect brain development and later function, our results suggest that this mechanism for the development of adult behavioral competence may be evolutionarily conserved. 相似文献
33.
Shabeesh Balan Sarada lekshmi Koramannil Radha Sanish Sathyan Joseph Vijai Moinak Banerjee Kurupath Radhakrishnan 《Gene》2013
The human major vault protein (MVP) has been implicated in the development of drug resistance in cancer cells. Over expression of MVP has also been reported in brain tissue samples from antiepileptic drug (AED)-resistant human focal epilepsies. To investigate the relationship between single nucleotide polymorphisms (SNPs) involving the MVP gene and AED-resistance, we compared the distribution of three SNPs in the MVP gene, rs4788187, rs3815824 and rs3815823, among 220 patients with mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) (prototype of AED-resistant epilepsy syndrome), 201 patients with juvenile myoclonic epilepsy (JME) (prototype of AED-responsive epilepsy syndrome) and 213 ethnically matched non-epilepsy controls. All the patients and controls were residents of the South Indian state of Kerala for more than three generations. We did not find any significant difference in allele and genotypic frequencies of the studied SNPs between AED-resistant and AED-responsive cohorts, and between AED-resistant and AED-responsive cohorts independently and pooled together when compared with the controls. We conclude that rs4788187, rs3815824, rs3815823 variants of the MVP gene are associated neither with predisposition for epilepsy nor with AED-resistance in the population that we have studied. Our results suggest the need for further research into the link between MVP and AED-resistance. 相似文献
34.
Govindan Bhaskaran Steven P. Sparagana Karl H. Dahm Punee Barrera Kenneth Peck 《Invertebrate reproduction & development.》2013,57(1):87-99
Summary The kinetic profiles of vitellin accumulation in the oyster ovary during oocyte growth and the effects in vivo and in vitro of estradiol-17β (E2) on vitellin formation were examined in this study. The relative vitellin content measured by an enzyme-linked immunosorbent assay (ELISA) shows an apparent increase as the oocyte develops. Immunoblotting of the vitellin using anti-vitellin indicated that two main bands (179 and 110 kD), which begin to accumulate at an early stage of maturation, become pronounced during oocyte growth. Meanwhile, the major peak of the intact form of vitellin (530 kD) in gel filtration also enlarges with oocyte growth, supporting the results of immunoblot analysis and vitellin determination. E2 treatment in vivo causes significant increases in oocyte diameter and vitellin content in the female oyster. A similar trend was observed in ovarian tissues cultured in the presence of E2. It is concluded that E2 is one of the major factors which control the vitellogenesis in the oyster and that the ovary is undoubtedly the site of synthesis of vitellin. 相似文献
35.
TOYOMI KOTAKI 《Invertebrate reproduction & development.》2013,57(1-3):225-230
Summary A radiochemical method was adopted to analyze the in vitro products of the corpus allatum (CA) of Plautia stali. The radiolabel derived from 3H-methionine added to the incubation medium was incorporated and released by CA as two main radiolabelled products. They showed Rf values of about 0.3 and 0.5, respectively, in the thin layer chromatography (TLC) system used. The release of these products was shown to be CA-specific since in control incubations using the brain, midgut, aorta and flight muscle, virtually no release of these products was observed. The locations where these main products migrated on the TLC did not coincide with spots of synthetic standards of JH I-III or JHB3, a JH found in higher Diptera. An addition of precursors of JH III, farnesoic acid or farnesol stimulated the CA to biosynthesize the products with an Rf value of 0.5 up to about 10-fold, suggesting that the product in question may have a sesquiterpenoid skeleton similar to JH III. Topical applications of the hexane extracts of the medium in which the CA had been incubated exerted a juvenilizing, metamorphosis-inhibiting effect on final instar nymphs in a dose-dependent fashion. The nymphs treated with the hexane extracts at a high dose moulted to intermediates with reduced forewings and scutellum, as well as nymphs implanted with the CA from reproductively active females. Based on this juvenilizing effect found in the hexane extracts, the JH-active fraction was determined after TLC separation. This assay indicated that the products found at an Rf value of about 0.5 was JH-active. These results suggest the presence of a new JH different from any known JHs in P. stali. 相似文献
36.
Mario La Mesa 《Polar Biology》2007,30(10):1219-1226
Juvenile Antarctic toothfish (Dissostichus mawsoni) collected off the South Shetland Islands (CCAMLR Subarea 48.1) were aged by counting the presumed daily increments in the
sagittal otoliths. The timing and position of the first annulus was examined for each individual fish from 10 to 13 cm TL.
Under reflected light at low magnification, the otolith sections exhibited a wide opaque nucleus, with no evidence of deposition
of the first translucent zone. The average measurement of ventral and dorsal radii of these sections were, respectively, 603
and 768 μm, consistently less than the measurements done in previously estimated 1 year old fish caught in the same area.
All specimens aged in the present study were approximately 1 year old fish, with an age range between 365 and 431 days, suggesting
a significant underestimation of age in the previous studies. The value of ageing precision indices calculated was relatively
low, supporting the reliability of the reading technique applied. Two checks were easily identified in the core of all otolith
sections, interpreted tentatively as hatching and first exogenous feeding checks. Back-calculating from the time of capture,
the hatching period of D. mawsoni was estimated to occur throughout the summer season, from November to February. In conclusion, the delay in timing of deposition
of the first translucent zone, which occurs in the second winter from hatching, should be taken into account in future studies
on ageing Antarctic toothfish, as well as in the stock assessment models based on length at age data. 相似文献
37.
Juvenile reef fish communities represent an essential component of coral reef ecosystems in the current focus of fish population
dynamics and coral reef resilience. Juvenile fish survival depends on habitat characteristics and is, following settlement,
the first determinant of the number of individuals within adult populations. The goal of this study was to provide methods
for mapping juvenile fish species richness and abundance into spatial domains suitable for micro and meso-scale analysis and
management decisions. Generalized Linear Models predicting juvenile fish species richness and abundance were developed according
to spatial and temporal environmental variables measured from 10 m up to 10 km in the southwest lagoon of New Caledonia. The
statistical model was further spatially generalized using a 1.5-m resolution, independently created, remotely sensed, habitat
map. This procedure revealed that : (1) spatial factors at 10 to 100-m scale explained up to 71% of variability in juvenile
species richness, (2) a small improvement (75%) was gained when a combination of environmental variables at different spatial
and temporal scales was used and (3) the coupling of remotely sensed data, geographical information system tools and point-based
ecological data showed that the highest species richness and abundance were predicted along a narrow margin overlapping the
coral reef flat and adjacent seagrass beds. Spatially explicit models of species distribution may be relevant for the management
of reef communities when strong relationships exist between faunistic and environmental variables and when models are built
at appropriate scales. 相似文献
38.
半滑舌鳎早期形态及发育特征 总被引:52,自引:0,他引:52
半滑舌鳎卵子为分离的球形浮性卵 ,卵径 1 18-1 3 1mm。卵膜薄、光滑、透明 ,具弹性。多油球 ,一般为 97-12 5个 ,多数在 10 0个左右 ,油球径 0 0 4-0 11mm。在培养水温为 2 0 5-2 2 8℃的条件下 ,卵子授精后 3 7h仔鱼孵出 ,3 0min后仔鱼全部孵出。初孵仔鱼全长 2 56-2 68mm。 1日龄仔鱼 ,出现胸鳍芽。 1 5日龄仔鱼 ,巡游模式基本建立。 2日龄仔鱼 ,逐渐建立外源性摄食关系。 3日龄仔鱼 ,出现鳔泡 ,个体发育进入后期仔鱼期。 18日龄 ,个体发育进入稚鱼期。 2 5日龄稚鱼 ,右眼开始向上移动。 2 7日龄稚鱼 ,右眼已转到头顶。 2 9日龄稚鱼 ,右眼完全转到左侧 ,胸鳍退化 ,各鳍鳍条发育完全。 57日龄 ,个体发育进入幼鱼期。 79日龄幼鱼 ,鳔退化、鳞片发育完全 ,侧线 3条。研究结果表明 :前期仔鱼培育期间 ,除了严格控制适宜的培养水温外 ,仔鱼开口后就应及时投喂一定密度的适口饵料 ,这是苗种培育中不可忽视的重要环节和技术措施之一 ;稚鱼变态期间加强鲜活饵料的投喂是提高稚鱼变态成活率的关键所在。仔鱼孵化后出现的管状感觉器官以及背、臀鳍膜上的泡状结构在早期发育阶段的生态和生理作用尚不清楚。半滑舌鳎成鱼无鳔和无胸鳍 ,而在早期发育期间具有鳔泡和胸鳍 ,这是生物个体发育史中祖先特征的重演 相似文献
39.
40.
Emilio Civantos 《Acta ethologica》2002,4(2):91-95
In some species, more aggressive individuals are more successful in resource competition. High testosterone level is associated
with increased activity and aggressive behavior, and this may have a direct effect on metabolic rate and cause an increase
in energy expenditure. Here, I examined the influence of exogenously administered testosterone on aggressiveness and body
growth in juvenile Psammodromus algirus male lizards. Juvenile males were given testosterone-filled (experimental) or empty (control) implants. Testosterone produced
an increase in aggressiveness and activity in the experimental males. However, despite being more aggressive, experimental
males did not acquire larger home ranges than control males. Experimental males also experienced a significant reduction in
growth rate over the 2-month period following implantation. Experimental males also were in poorer condition at the completion
of the experiment, compared to control males. These results suggest that although an elevated testosterone level may have
positive effects on aggressiveness and activity, it also may have negative effects manifested as reduced growth rate and body
condition.
Received in revised form: 15 June 2001
Electronic Publication 相似文献