Photoperiod regulation of neuron death in the adult canary

The avian brain undergoes naturally occurring cell death and neuronal replacement in adulthood. Little is known about how neuron survival in adult birds is regulated. However, previous work suggests that this process is open to environmental control. We now report that a reduction in day length from springlike to fall-like conditions can dramatically increase cell death in adult male canaries. Many of the dying cells are projection neurons in the motor pathway controlling song learning and production. Circulating levels of gonadal steroids were not correlated with photoperiod-induced changes in the magnitude of cell death. Our results suggest that neuronal death in adult male canaries is regulated by seasonal changes in photoperiod, and that this occurs independent of chronic changes in gonadal steroid hormone levels. Day length may serve as a predictive environmental cue to time cell death in accordance with seasonal reproduction. © 1997 John Wiley & Sons, Inc. J Neurobiol 33: 223–231, 1997

1 This is a US Government work and, as such, is in the public domain in the United States of America.

     

Successful ovulation induction and laparoscopic intrauterine artificial insemination in the clouded leopard (Neofelis nebulosa)

Exogenous gonadotropins and a laparoscopic intrauterine artificial insemination (AI) technique were assessed for effectiveness in the clouded leopard (Neofelis nebulosa), a species difficult to breed in captivity due to severe mate incompatibility. Fourteen hormone trials using 10 female clouded leopards were performed to evaluate the ability of 50, 100, or 200 i.u. pregnant mares' serum gonadotropin (PMSG) and 75 or 100 i.u. human chorionic gonadotropin (hCG) to induce folliculogenesis and ovulation, respectively. Laparoscopic evaluation of ovarian activity was conducted at 29–48 hr after hCG administration. Time of ovulation in PMSG/hCG-treated clouded leopards was approximately 38–39 hr after hCG. Excessive follicular development was observed using the high hormone dosages (200 i.u. PMSG/100 i.u. hCG), whereas the lower dosages avoided ovarian hyperstimulation. Previous ovulation sites and mature corpora lutea were detected upon laparoscopic examinations in two of the 10 females housed alone, indicating that this species occasionally spontaneously ovulates. Five females were inseminated by depositing electroejaculated, washed sperm transabdominally into the proximal aspect of each uterine horn. One postovulatory female, previously treated with 100 i.u. PMSG and 75 i.u. hCG and inseminated in utero with 88 × 10⁶ motile sperm at 45 hr post-hCG, produced a pregnancy and two live cubs after an 89 day gestation. These results demonstrate: (1) an exquisite ovarian sensitivity to exogenous gonadotropins in clouded leopards; and (2) that artificial insemination has the potential of resulting in offspring in this species. (This article is a US Government work and, as such, is in the public domain in the United States of America.) © 1996 Wiley-Liss, Inc.     

Novel non-peptide lead structures forBradykinin B2-receptor antagonists

Summary A series of new non-peptide Bradykinin (BK) B₂-receptor antagonists is reported. These new leads belong to a larger set including both commercially or otherwise available potential candidates found by proprietary database searches using 3D-pharmacophore models as query, and several bis-benzamidino compounds selected from our tryptase-like protease inhibitor library on the basis of topological considerations, derived from the same models. Some of these compounds show functional competitive antagonistic activity, inhibiting in vitro the BK-induced contraction of isolated guinea-pig ileum (GPI) and rat uterus with a pA₂ up to 5.3 and 7.0, respectively. They display also binding affinity (IC₅₀ up to 0.56 μM) to the BK B₂-receptor in radioligand binding assays on GPI membrane preparations and on human IMR-90 fetal lung fibroblast cells expressing this receptor subtype. Furthermore, the results with the commercially available compounds, in some cases developed as therapeutics, show that the used 3D-pharmacophore model allows to predict to some certainty possible side actions of potential drugs.     

Colonial organization and intercellular communication in microorganisms

This review covers the modern concepts and recent data demonstrating the integrity and coherence of microbial populations (colonies, biofilms, etc.) as peculiar “superorganisms.” Special attention is given to such relevant phenomena as apoptosis, bacterial altruism, quorum effects, collective differentiation of microbial cells, and the formation of population-level structures such as an extracellular matrix. Emphasis is placed on the channels and agents of intercellular communication in microbial populations. The involvement of a large number of evolutionarily conserved communicational facilities and patterns of intercellular interactions is underscored. Much attention is also given to the role of colonial organization and intercellular communication in parasite/commensal/symbiont-multicellular host organism systems.     

曼地亚红豆杉对自然降温的适应性研究

 以3年生的曼地亚红豆杉（Taxus media cv. Hicksii）为材料,对其在自然降温过程中的适应性进行了研究,结果表明：随着气温的降低,曼地亚红豆杉低温半致死温度不断降低,由秋季的-8.13 ℃降低到冬季最冷的1月中旬的-13.01 ℃;渗透调节物质可溶性总糖、可溶性蛋白质、游离脯氨酸含量均不同程度增加,而淀粉总含量降低;内源激素ABA含量不断升高,与低温半致死温度呈负相关（相关系数为-0.971 06）,而ZRs、GA1/3、IAA含量降低,与低温半致死温度呈正相关（相关系数分别为0.949 72、0.813 6、 0.697 5）。综上所述,在自然降温过程中,这些物质的适应性变化导致了曼地亚红豆杉低温半致死温度的降低,从而使曼地亚红豆杉能很好地适应重庆栽培地的低温条件而安全过冬。     

Functional interactions between steroid hormones and neurotrophin BDNF

Brain-derived neurotrophic factor (BDNF), a critical neurotrophin, regulates many neuronal aspects including cell differentiation, cell survival, neurotransmission, and synaptic plasticity in the central nervous system (CNS). Though BDNF has two types of receptors, high affinity tropomyosin-related kinase (Trk)B and low affinity p75 receptors, BDNF positively exerts its biological effects on neurons via activation of TrkB and of resultant intracellular signaling cascades including mitogen-activated protein kinase/extracellular signal-regulated protein kinase, phospholipase Cγ, and phosphoinositide 3-kinase pathways. Notably, it is possible that alteration in the expression and/or function of BDNF in the CNS is involved in the pathophysiology of various brain diseases such as stroke, Parkinson's disease, Alzheimer's disease, and mental disorders. On the other hand, glucocorticoids, stress-induced steroid hormones, also putatively contribute to the pathophysiology of depression. Interestingly, in addition to the reduction in BDNF levels due to increased glucocorticoid exposure, current reports demonstrate possible interactions between glucocorticoids and BDNF-mediated neuronal functions. Other steroid hormones, such as estrogen, are involved in not only sexual differentiation in the brain, but also numerous neuronal events including cell survival and synaptic plasticity. Furthermore, it is well known that estrogen plays a role in the pathophysiology of Parkinson's disease, Alzheimer's disease, and mental illness, while serving to regulate BDNF expression and/or function. Here, we present a broad overview of the current knowledge concerning the association between BDNF expression/function and steroid hormones (glucocorticoids and estrogen).     

Probiotics function mechanistically as delivery vehicles for neuroactive compounds: Microbial endocrinology in the design and use of probiotics

I hypothesize here that the ability of probiotics to synthesize neuroactive compounds provides a unifying microbial endocrinology-based mechanism to explain the hitherto incompletely understood action of commensal microbiota that affect the host's gastrointestinal and psychological health. Once ingested, probiotics enter an interactive environment encompassing microbiological, immunological, and neurophysiological components. By utilizing a trans-disciplinary framework known as microbial endocrinology, mechanisms that would otherwise not be considered become apparent since any candidate would need to be shared among all three components. The range of neurochemicals produced by probiotics includes neurochemicals for which receptor-based targets on immune and neuronal elements (intestinal and extra-intestinal) have been well characterized. Production of neurochemicals by probiotics therefore allows for their consideration as delivery vehicles for neuroactive compounds. This unifying microbial endocrinology-based hypothesis, which may facilitate the selection and design of probiotics for clinical use, also highlights the largely unrecognized role of neuroscience in understanding how microbes may influence health.     

Sex differences in bone resorption in the mouse femur

Summary In male and female dd-mice at 4, 7, and 14 weeks of age and in 7 and 14-week-old mice gonadectomized at 4 weeks of age, the number of osteoclasts and the number and size of bone resorption areas along the surface of bone trabeculae in the distal metaphysis of the femur were determined. Osteoclasts were counted at the light-microscopic level in paraffin sections of decalcified femora. The number and size of the bone resorption areas were examined by scanning electron microscopy of femora after removing organic material by means of KOH and NaOCl treatment. In untreated mice, the number of osteoclasts and the number and size of bone resorption areas showed no sex differences at 4 weeks of age but were larger in females than males at 7 and 14 weeks of age. In gonadectomized mice, the number of osteoclasts and the bone resorption areas increased in males and decreased in females. The results of the gonadectomy experiments suggest that bone resorption in young adult mice is stimulated by female sex hormone and inhibited by male sex hormone.