Photorefractoriness in Japanese quail: possible involvement of the thyroid gland

Quail have a form of refractoriness to long daylengths that is relative and not absolute. The properties of "relative refractoriness" are compared with the more typical "absolute" form seen in starlings and the question is posed as to whether the two types represent the extremes of a single underlying process or are quite separate phenomena. A model is offered that assumes that a single process is involved, and some tests of the hypothesis, notably the involvement of the thyroid gland, are described.     

Hypothalamic regulation of testicular function in Japanese quail

Summary Some of the components of the system that controls the function of the testes of the Japanese quail were identified by means of midline or bilateral electrolytic or radio-frequency coagulation of various regions of the hypothalamus. The destruction of two identifiable regions of the ventral hypothalamus resulted in different forms of testicular dysfunction. Extensive medial or bilateral damage to the infundibular nuclear complex, ventral regions thereof (including the tuberal nuclei), the entire median eminence or its posterior division resulted in regression of both the gametogenic and endocrine components of the testis and regression of the cloacal gland, an anal gland known to depend on testosterone for normal function. Damage to more anterodorsal regions of the infundibular nuclear complex resulted, in a single bird, in regression of the seminiferous tubules, but had no noticeable effect on the cells of Leydig; the cloacal gland of this bird, although reduced somewhat in size, appeared histologically active. Unilateral damage to the infundibular nuclear complex or the median eminence, or bilateral destruction of the antero—or posteroventral portions of the infundibular nuclear complex did not affect testicular function. The differing testicular dysfunctions are discussed in relation to the release of LH and FSH from the adenohypophysis.This investigation was supported by NIH Predoctoral Fellowship GM-33,458 to the author, and by Research Grants from the National Science Foundation (GB-11905) and the National Institutes of Health (NB-06187) to Professor Donald S. Farner. This paper is based on a dissertation (Stetson, 1971b) submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Zoology at the University of Washington. The hormones used in this investigation were generously supplied by the Endocrinology Study Section of the National Institutes of Health.     

The effects of dietary iodine on thyroid ultrastructure

This is a morphological study of changes in thyroid cells following iodine deficiency and iodine excess. Fifteen young male Sprague-Dawley rats were divided into three groups and fed one of the following diets for 6 weeks: low iodine (LID), normal iodine (NID) and high iodine (HID). Then the thyroid glands were removed and processed for light and electron microscopy. Thyroid tissue from the NID group was normal in appearance. The most outstanding feature of HID thyroids was the presence of numerous cells which contained irregularly shaped and stained lysosomes. These displaced other cell organelles and caused the apical cell surfaces to project into the follicle lumen. Thyroids from the LID group were three times heavier than the other two groups. Their follicles were very small, contained very little colloid. They were surrounded by dilated capillaries. Mitoses were frequent. Cells were columnar and contained abundant dilated endoplasmic reticulum, numerous apical vesicles, long microvilli and many mitochondria. Mitochondria were especially abundant in greatly infolded lateral and basal cell membranes. These findings show that there is a redistribution of organelles in thyroid cells in response to iodine deficiency and iodine excess which can be related to alterations in intracellular iodine metabolism.     

Lesion-induced neurogenesis in the hypothalamus is involved in behavioral recovery in adult ring doves

Although neurogenesis in the brain of adult vertebrates is region dependent, lesion induces generation of new neurons in non-neurogenic brain regions. These findings raise the question of the role of new neurons in brain repair and functional recovery. We addressed this question by applying previous observations that electrolytic lesion induced neurogenesis in the ventromedial nucleus (VMN) of the hypothalamus in adult ring doves. Such lesions disrupted the male's courtship behavior, which could be reinstated after rehabilitation with a female. We investigated whether lesion-induced newborn neurons in the VMN facilitate the recovery of courtship behavior in the lesioned birds. We conducted systematic observations of cytological, morphological, and neuroanatomical changes in the lesioned VMN, and concurrently we monitored behavioral changes. Using a multitude of specific cell markers, we found a well-circumscribed cellular zone that proliferated actively. This highly proliferative zone initially appeared along the periphery of the lesion site, where cells had high levels of expression of neuronal, glial, and neurovascular markers. As newborn neurons matured at the lesion site, the necrosis gradually decreased, whereas a downsized proliferative zone relocated to a region ventral to the VMN. Some of the mature neurons were found to project to the midbrain vocal nuclei. Restoration of these projection neurons coincided with the recovery of courtship vocalization. Finally, we found that a social factor, that is, when the male doves were cohoused with a mate, facilitated neurogenesis and behavioral recovery. These results suggest that lesion-induced neurogenesis contributes to behavioral recovery in adult animals.     

Post-hatch heat warms adult beaks: irreversible physiological plasticity in Japanese quail

Across taxa, the early rearing environment contributes to adult morphological and physiological variation. For example, in birds, environmental temperature plays a key role in shaping bill size and clinal trends across latitudinal/thermal gradients. Such patterns support the role of the bill as a thermal window and in thermal balance. It remains unknown whether bill size and thermal function are reversibly plastic. We raised Japanese quail in warm (30°C) or cold (15°C) environments and then at a common intermediate temperature. We predicted that birds raised in cold temperatures would develop smaller bills than warm-reared individuals, and that regulation of blood flow to the bill in response to changing temperatures would parallel the bill''s role in thermal balance. Cold-reared birds developed shorter bills, although bill size exhibited ‘catch-up’ growth once adults were placed at a common temperature. Despite having lived in a common thermal environment as adults, individuals that were initially reared in the warmth had higher bill surface temperatures than cold-reared individuals, particularly under cold conditions. This suggests that blood vessel density and/or the control over blood flow in the bill retained a memory of early thermal ontogeny. We conclude that post-hatch temperature reversibly affects adult bill morphology but irreversibly influences the thermal physiological role of bills and may play an underappreciated role in avian energetics.     

Maternal dietary carotenoids mitigate detrimental effects of maternal GnRH on offspring immune function in Japanese quail Coturnix japonica

Maternal resources deposited in eggs can affect the development of several offspring phenotypic traits and result in trade‐offs among them. For example, maternal androgens in eggs may be beneficial to offspring growth and competitive ability, but detrimental to immunocompetence and oxidative stress. In contrast, maternal antioxidants in eggs may be beneficial if they mitigate oxidative stress and immunosuppressive effects of androgens. We investigated possible interactive effects of maternal steroids and carotenoids on aspects of offspring physiology and phenotype, by simultaneously manipulating levels of androgens (via gonadotropin‐releasing hormone, GnRH‐challenges) and carotenoids (via diet supplementation) in captive female Japanese quail Coturnix japonica during egg laying. Carotenoid supplementation of hens, which elevates yolk concentrations of carotenoid and vitamins A and E, enhanced egg hatching success, offspring survival to age 15 d, and size of the bursa of Fabricius in offspring. In contrast, repeated maternal GnRH challenges, which elevated yolk testosterone concentrations, enhanced offspring neonatal size, but negatively affected bursa size. However, interaction among the treatments suggests that the positive effect of maternal carotenoid supplementation on plasma bactericidal capacity was mediated by maternal GnRH challenges. Chicks originating from carotenoid‐supplemented hens were less immunosuppressed than those originating from carotenoid‐supplemented + GnRH‐challenged hens, which were less immunosuppressed than chicks from GnRH‐challenged females not supplemented with carotenoids. Females availability of carotenoid enriched diets allows them to enhance the development of offspring immune system via carotenoids and vitamins deposited in egg yolks and offset detrimental effects of androgens deposited by GnRH‐challenged females.     

Androgen influence on mating behavior in selected lines of Japanese quail

Bidirectional selection for high and low mating behavior has resulted in lines of Japanese quail that differ significantly in mating frequency. To evaluate the effects of this selection on the endocrine aspects of mating behavior, exogenous testosterone cypionate (TC) was administered to caponized and intact males from selected and control lines. Dosages of TC, administered as a single injection, were 0, 5.0, and 10.0 mg for the caponized and 1.25, 2.5, and 5.0 mg for the intact males. Mating performance was measured by testing each male individually with a series of female tester-flocks for eight 8-min periods.Capons mated within 3 to 4 days postinjection, with the period of peak activity occurring between the eighth and twelfth days. Hypertrophy of the cloacal gland followed a similar pattern. At no TC level was the mating frequency of caponized males from the low mating line equal to that of males from the high mating line. Furthermore, exogenous TC at these dosages failed to stimulate capons from the high and low mating lines to mate as frequently as the intact males of their respective lines. Exogenous TC had a depressing effect upon the mating frequency of intact males from the high mating and control lines but had no influence on those from the low mating line.     

Comparative FISH mapping on Z chromosomes of chicken and Japanese quail

Using direct R-banding fluorescence in situ hybridization, we assigned five functional genes-growth hormone receptor (GHR), prolactin receptor (PRLR), spleen tyrosine kinase (SYK), aldolase B (ALDOB), and muscle skeletal receptor tyrosine kinase (MUSK)-to the chicken Z chromosome. SYK and MUSK were newly localized to the chicken Z chromosome in this study. GHR and PRLR were situated close to each other on the short arm of the chicken Z chromosome, as are their counterparts on human chromosome 5. SYK, MUSK, and ALDOB, which have been mapped to human chromosome 9, were localized to the long arm of the chicken Z chromosome. Thus, the present results indicate the presence of conserved synteny between the chicken Z chromosome and human chromosomes 5 and 9. Using the same method, four of the genes (GHR, PRLR, ALDOB, and MUSK) were assigned to the Japanese quail Z chromosome. The locations of these four Z-linked genes were conserved between chicken and Japanese quail. The results support the notion that the avian Z chromosome and the mammalian X chromosome did not evolve from a common ancestral linkage group.     

Lesion‐induced neurogenesis in the hypothalamus is involved in behavioral recovery in adult ring doves

Although neurogenesis in the brain of adult vertebrates is region dependent, lesion induces generation of new neurons in non‐neurogenic brain regions. These findings raise the question of the role of new neurons in brain repair and functional recovery. We addressed this question by applying previous observations that electrolytic lesion induced neurogenesis in the ventromedial nucleus (VMN) of the hypothalamus in adult ring doves. Such lesions disrupted the male's courtship behavior, which could be reinstated after rehabilitation with a female. We investigated whether lesion‐induced newborn neurons in the VMN facilitate the recovery of courtship behavior in the lesioned birds. We conducted systematic observations of cytological, morphological, and neuroanatomical changes in the lesioned VMN, and concurrently we monitored behavioral changes. Using a multitude of specific cell markers, we found a well‐circumscribed cellular zone that proliferated actively. This highly proliferative zone initially appeared along the periphery of the lesion site, where cells had high levels of expression of neuronal, glial, and neurovascular markers. As newborn neurons matured at the lesion site, the necrosis gradually decreased, whereas a downsized proliferative zone relocated to a region ventral to the VMN. Some of the mature neurons were found to project to the midbrain vocal nuclei. Restoration of these projection neurons coincided with the recovery of courtship vocalization. Finally, we found that a social factor, that is, when the male doves were cohoused with a mate, facilitated neurogenesis and behavioral recovery. These results suggest that lesion‐induced neurogenesis contributes to behavioral recovery in adult animals. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006     

The nature of thyrotropin stimulation of thyroid function in Japanese quail: prolonged thyrotropin exposure is necessary to increase thyroidal 125I uptake

Single injections of thyrotropin (TSH) increase serum T4 and thyroidal 32P uptake but not thyroidal 125I uptake regardless of dosage, exposure time or age. Chronic TSH exposure, with 3 or more days of injection, does increase thyroidal 125I uptake. Studies using iodine (I) supplementation indicated that the increased thyroidal radioiodine uptakes seen with chronic TSH administration were not due to an I deficiency in the thyroid resulting from high hormone release. Labeled and unlabeled experiments comparing the effects of single vs. multiple injections of TSH were used to describe the effects of TSH on hormone release, hormone production and thyroidal I uptake.     

Effect of dietary iodine on thyroid hormones and energy blood metabolites in lactating goats

Aim of this work was to evaluate if long-term dietary supplementation of potassium iodide (KI) to dairy goats can influence metabolic and hormonal parameters. Thirty Sarda crossbred dairy goats were divided into three groups, which were orally administered 0 (control group; CON), 0.45 (low iodine group; LI) or 0.90 (high iodine group; HI) mg of KI/day, respectively. The daily dose of KI (76.5% of iodine) was administered as salt dissolved in water for 8 weeks. Plasma contents of nonesterified fatty acids (NEFA), urea, glucose, insulin, free triiodothyronine (FT₃) and thyroxine (FT₄) were determined weekly. Iodine supplementation increased significantly the FT₃ hormone (P = 0.007) and FT₃/FT₄ ratio (P = 0.001) and tended to influence the FT₄ hormone (P = 0.059). An iodine level × week of sampling interaction for NEFA (P = 0.013) evidenced a temporary concentration increase in supplemented groups. The ‘Revised Quantitative Insulin Sensitivity Check Index’ increased with KI supplementation (P ⩽ 0.01). Blood urea nitrogen (BUN) and insulin were lowered (P ⩽ 0.01) by iodine supplementation (groups LI and HI; P ⩽ 0.01). The glucose concentration evidenced an iodine level × week of sampling interaction (P = 0.025) due to an unexpected and temporary increase of its concentration in the CON group. Glucose concentration was decreased by KI supplementation only in LI group (P < 0.05). In conclusion, the daily supplementation of low doses of KI can improve insulin sensitivity and decrease BUN in dairy goats.     

Relationship between mild iodine deficiency in pregnant women and thyroid function: A meta-analysis

BackgroundPregnant women are among the key groups in iodine nutrition evaluation. The purpose of the present study was to summarize the evidence supporting the relationship between mild iodine deficiency (UIC: 100–150 μg/L) in pregnant women and levels of thyroid function tests.MethodsThis review follows the guidelines for systematic reviews (PRISMA 2020). Three electronic databases (PubMed, Medline, and Embase) were searched for relevant publications in English on the association between mild iodine deficiency in pregnant women and thyroid function. Articles published in Chinese were searched in China’s electronic databases (CNKI, WanFang, CBM, and WeiPu). Pooled effects were presented as standardized mean differences (SMDs) and odds ratios (ORs) with 95% confidence intervals (CIs) using fixed or random effect models, respectively. This meta-analysis was registered at www.crd.york.ac.uk/prospero as CRD42019128120.ResultsWe summarized the results from 7 articles with 8261 participants. The overall pooled results showed that the levels of FT₃, FT4, and abnormal TgAb (the antibody levels exceeded the upper limit of the reference range) were significantly increased in pregnant women with mild iodine deficiency compared to pregnant women with adequate iodine status (FT₃: SMD=0.854, 95% CI: 0.188, 1.520; FT₄: SMD=0.550, 95% CI: 0.050, 1.051; TgAb: OR=1.292, 95% CI: 1.095; 1.524). Subgroup analysis was carried out on the sample size, ethnicity, country, and gestation of FT₃, FT_4, and TSH, but no plausible factor was found. Egger’s tests indicated no publication bias.The increase in FT₃ and FT_4, as well as TgAb levels, in pregnant women is associated with mild iodine deficiency.ConclusionMild iodine deficiency is associated with an increase in FT_3,FT₄ and TgAb levels in pregnant women. Mild iodine deficiency may increase the risk of thyroid dysfunction in pregnant women.