Reproductive and metabolic hormones during estrus after fasting in Holstein heifers

The estrous cycles of 23 Holstein heifers were synchronized with three prostaglandin F₂α (PG) injections at 0600 h 11 d apart, designated as Days ?11, 0 and 11. Twelve of the animals were randomly assigned to receive no solid food (Group F) from Day 6 to 14, while the other animals remained on full feed to serve as controls (Group C). Jugular blood samples were collected at 6-h intervals beginning with PG injection at 0600 h on Day 0 until 1800 h on Day 4 and at 0600, 1200 and 1700 h on Day 8 through 10. Samples were collected again at 6-h intervals from PG Day 11 (0600 h) until 1800 h on Day 15. Period 1 was defined as those samples collected from Day 0 through 4.5, Period 2 from Day 7 through 10, Period 3 from Day 11 through 14.25, and Period 4 from Day 14.5 through 15. Plasma growth hormone concentrations were increased (P<0.01) in F as compared with C animals during Periods 2, 3 and 4. Plasma concentrations of prolactin (P<0.01) were decreased in F as compared with C animals during Periods 2 and 3. Plasma urea concentrations were increased (P<0.01) in F as compared with C animals during the first 3 d of the fast (Period 2) but were decreased (P<0.01) during the remainder of the experiment (Periods 3 and 4). Thus, fasting was effective in altering several metabolic parameters. Although plasma progesterone and luteinizing hormone (LH) concentrations remained similar (P>0.05) between F and C animals, plasma estradiol-17β concentrations decreased in F as compared with C animals during Periods 2, 3 and 4. No differences (P>0.05) between F and C animals were found in duration to LH peak after PG injection, estrous behavior, or pregnancy rates. Results from this study indicate that fasting reduced plasma estradiol-17β concentrations during estrus but did not alter occurrence of estrus or pregnancy rate.     

Possible correlation between high temperature-induced floret sterility and endogenous levels of IAA,GAs and ABA in rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

In order to explore the possible physiological mechanism of high temperature induced sterility in rice, we examined the floret sterility and endogenous plant growth regulator contents in pollens of two hybrid rice cultivars Shanyou63 and Teyou559 that are tolerant and susceptible to high temperature, respectively. Indexes of floret sterility, pollen activity, and variation of endogenous indole-3-acetic acid (IAA), gibberellic acids (GAs), abscisic acid (ABA), free proline and soluble proteins in anthers were measured. We found that during the course of high temperature treatment, both cultivars exhibited a marked decrease in pollen activity, pollen germination and floret fertility; however, the high temperature tolerant Shanyou63 showed a much slower rate of decrease than the high temperature susceptible Teyou559. In addition, anthers of both cultivars displayed a decrease in the contents of IAA, GAs, free proline and soluble proteins but an increase in the ABA content. Yet compared to Teyou559, Shanyou63 retained significantly higher levels of free praline and GAs and a lower level of ABA, along with higher pollen vigour and pollen germination rate even after prolonged high temperature treatment. Our study suggests a possible correlation between pollen viability/floret sterility and high temperature-caused changes in IAA, GAs, ABA, free proline and soluble protein contents. The severity in these changes may reflect the variation of rice cultivars in their heat stress sensitivities for floret development.     

Effect of serum estradiol and leptin levels on thyroid function, food intake and body weight gain in female Wistar rats

We evaluated the interplay among estrogen, leptin and thyroid function in the regulation of body mass in female rats. Adult female rats were divided into four groups: control (C, sham-operated), ovariectomized (OVX), ovariectomized treated with estradiol benzoate (Eb) 0.7 or 14 μg/100 g bw per day, during 21 days. OVX led to an increase in body mass, food intake and food efficiency (change in body mass as function of the amount of food ingested) which were normalized by the lower Eb dose, and decreased significantly when the higher dose was given. Serum leptin levels were increased more than two-fold in all ovariectomized groups. Serum T4 levels of the Eb treated OVX were significantly lower than in the controls. Serum T3 and TSH were unaffected by OVX or by Eb treatment. Uterine type 2 iodothyronine deiodinase (D2) activity changed in parallel with serum estradiol: decreased after OVX, returned to control levels after the lower E2 treatment, and increased significantly after the high Eb dosage. The hypothalamic D2 activity was reduced around 30% in all castrated groups, treated or not with estrogen, whereas in the brown adipose tissue the enzyme was not changed. Interestingly, although estrogen-treated OVX rats had lower body weight, serum leptin was high, suggesting that estrogen increases leptin secretion. Our results show that estradiol is necessary for the hypothalamic action of leptin, since the increase in leptin levels observed in all ovariectomized rats was associated with a decrease in food intake and food efficiency only in the rats treated with estrogen.     

Effect of exogenous hormones on leaf yellowing in cut flowering branches of Alstroemeria pelegrina L.

Inclusion of IAA in the vase water had little effect on leaf yellowing in cut flowering branches of Alstroemeria pelegrina L. while kinetin delayed leaf yellowing at 10^-4M (continuous treatment). Chlorophyll was effectively retained by 10^-7M gibberellic acid (GA) in the vase water or by a 20h pulse at 5°C with 10^-5/10^-4M GA. After 16h of ¹⁴C-GA, uptake at 20°C relatively high levels of ¹⁴C were found in leaves and low levels in stems and flowers. After this treatment about half of the ¹⁴C-GA, in leaves was metabolized into unknown compounds. Corrigendum. Owing to an error in the proofreading process, the article was published incorrectly. The article as it should have been published is presented here.     

Production of bioactive peptides in an in vitro system

An in vitro system for the preparation of bioactive peptides is described. This system couples three different posttranslational modification enzymes, prohormone convertases (PCs), carboxypeptidase E, and peptidyl alpha-amidating enzyme, to transform recombinant precursors into bioactive peptides. Three different precursors, mouse proopiomelanocortin (mPOMC), rat proenkephalin (rPE), and human proghrelin, were used as model systems. The conversion of mPOMC and rPE to smaller peptide products was measured by radioimmunoassay. After optimization of the system, excellent efficiency was obtained: about 85% of starting mPOMC was converted to des-acetyl alpha-melanocyte-stimulating hormone (alpha-MSH). For proenkephalin, 75 and 96% yields were obtained for the opioid peptides Met-RGL and Met-enk, respectively. Cell-based assays demonstrated that in-vitro-generated des-acetyl alpha-MSH successfully activated the melanocortin 4 receptor. Proghrelin digestion was used to screen the specificity of PC cleavage and to confirm the cleavage site by mass spectroscopy. Mature ghrelin was produced by human furin, mouse prohormone convertase 1, and human prohormone convertase 7 but not by mouse prohormone convertase 2. These results demonstrate that our in vitro system (1) can produce peptides in quantities sufficient to carry out functional analyses, (2) can be used to determine the specificity of proprotein convertases on recombinant precursors, and (3) has the potential to identify novel peptide functions on both known and orphan G-protein-coupled receptors.     

Transient growth‐enhancing effects of elevated maternal thyroid hormones at no apparent oxidative cost during early postnatal period

Maternal thyroid hormones (THs) have been proven crucial for embryonic development in humans, but their influence within the natural variation on wild animals remains unknown. So far the only two studies that experimentally investigated the potential fitness consequences of maternal THs in birds found inconsistent results. More studies are thus required to assess the general effects of maternal THs and their influences on more behavioral and physiological parameters. In this study, we experimentally elevated yolk TH content in a wild migratory passerine species, the collared flycatcher Ficedula albicollis, to investigate the effects on hatching success, nestling growth and oxidative stress. We found that TH‐injected eggs had a higher hatching success, and the nestlings hatched from TH‐injected eggs were heavier and larger than control nestlings, but only during the early postnatal period. These differences vanished by fledging. Nestlings from TH‐injected eggs exhibited lower activity of the glutathione‐s‐transferase, a major antioxidant enzyme, than control nestlings at day 12, a few days before fledging, but they did not differ in oxidative damage and overall intracellular oxidative state. These results suggest that the early growth‐enhancing effects incurred no observable oxidative stress. We hypothesize that such a transient growth‐enhancing effect might be adaptive in advancing the development and maturation of the offspring so they are well‐prepared in time for the upcoming migration. Further studies investigating whether such advancing effects can influence long‐term fitness, will be more than valuable.     

Effects of a brassinosteroid on growth and on H+-extrusion in isolated radish cotyledons: comparison with the effects of benzyladenine

We investigated the effect of 24-epibrassinolide (BR) on the cytokinin-bioassay based on growth of isolated radish ( Raphanus sativus L. cv. Tondo Rosso Quarantino) cotyledons. BR stimulated growth of the cotyledons by about 50% when applied at saturating concentrations (3 μ M ). This effect was much lower than that of saturating concentrations of benzyladenine (BA) which was about 150% at 10 μ M BA. The effects of saturating concentrations of BR and BA were additive. BR, but not BA, stimulated H⁺-secretion by the cotyledons (measured as acidification of the incubation medium) slightly but reproducibly. These results indicate that the modes of action of the two phytoregulators are at least partially different.
BR-induced stimulation of H⁺-secretion was of similar amplitude to that induced by a concentration of fusicoccin (30 n M ) such as to stimulate growth to the same extent as BR. These results suggest that BR-induced stimulation of radish cotyledon growth might depend, at least in part, on BR-induced acidification of the wall space, similar to that observed on Azuki bean epicotyls and maize roots.     

Steroid hormones and plant growth and development

The occurrence of steroid hormones in plants is briefly reviewed. Their effects on plant growth, development and flowering are also considered.     

An immunohistochemical study of epithelial cells in the posterior lobe and pars tuberalis of the human adult pituitary gland

Summary Pituitary glands were examined using reference staining (hematoxylin and eosin, periodic acid-Schiff and alcian blue) and the peroxidase-labeled antibody method, for 1) invading anterior cells in the posterior lobe, 2) intermediate colloid forming follicles, and 3) pars tuberalis cells.The results showed: 1) that the majority of cases possessed invading anterior cells of various amount. Most of these cells were positive for ACTH^1–18, ACTH^17–39 and -MSH. However, on a few occasions, scattered GH, PRL, FSH, FSH, LH and even TSH cells were also present. 2) Colloid forming follicular cells were mostly ACTH cells, but also contained occasional other hormone-secreting cells. Hormone negative cells were correlated with salivary type epithelium. Well established acinic type salivary glands and ciliated epithelium were negative for any hormones immunohistochemically. 3) Pars tuberalis cells were predominantly gonadotrophs but also included TSH and ACTH cells. Some cells appeared to contain both FSH and LH. When these cells underwent squamous metaplasia, they seemed to lose their hormone secreting activity.Part of this study was supported by a Grant-in-Aid for Cancer Research from the Ministry of Education, Science and Culture, Japan