Sex Accessories Morphology and Functions during the Seasonal Testicular Cycle of a Subtropical Wild Avian Species, the Yellow-Throated Sparrow Petronia xanthocollis Burton

Annual changes in the male sex accessories (tubuli recti, rete testis, vasa efferentia, epididymis, vas deferens and seminal glomus) were studied during the annual testicular cycle of the yellow-throated sparrow ( Petronia xanthocollis Burton). All the segments of genital tract and the seminal glomus became enlarged during the progressive phase (January to March), were maximally enlarged during breeding (April), began to decrease during regression (May and June) and became maximally regressed during the nonbreeding phase (July to December). But the sialic acid level of the seminal glomus increased to maximum already during the progressive phase, remained high during breeding and declined subsequently. The findings suggest that the male sex accessories functions vary distinctly with the annual testicular cycle presumably due to alterations in the testicular androgen production in the yellow-throated sparrow.     

Oviductal Function during the Annual Ovarian Cycle of a Wild Avian Species,the Tree Pie Dendrocitta vagabunda

The present investigation was carried out on oviductal activity during the annual ovarian cycle of the Indian tree pie (Dendrocitta vagabunda). The oviductal activity was evaluated by weight, length, histology (gross and quantitative) and peroxidase, acid phosphatase, alkaline phosphatase, sialic acid, glycogen, RNA and protein concentrations of different regions of the oviduct. All these values w ere low during the nonbreeding phase (August to January), increased during the progressive phase (February to March), became maximum during breeding (April to May) and decreased in the regression phase (June to July). The functional change of the oviduct is suggested to be due to fluctuation of ovarian steroid activity in this avian species.     

Oviductal Function during the Annual Ovarian Cycle of a Wild Avian Species, the Tree Pie Dendrocitta vagabunda

The present investigation was carried out on oviductal activity during the annual ovarian cycle of the Indian tree pie ( Dendrocitta vagabunda ). The oviductal activity was evaluated by weight, length, histology (gross and quantitative) and peroxidase, acid phosphatase, alkaline phosphatase, sialic acid, glycogen, RNA and protein concentrations of different regions of the oviduct. All these values w ere low during the nonbreeding phase (August to January), increased during the progressive phase (February to March), became maximum during breeding (April to May) and decreased in the regression phase (June to July). The functional change of the oviduct is suggested to be due to fluctuation of ovarian steroid activity in this avian species.     

Relation between the Adrenals and Thyroid and their Hormones and the Testicular cycle of a Subtropical Avian Species

In order to understand the hormonal interactions throughout the reproductive phases (non-breeding, progressive, breeding and regressive) of a sub-tropical avian species, the male common myna ( Acriodotheres tristis ), hormones like epinephrine (E), norepinephrine (NE), corticosterone, tri-iodothyronine (T 3 ), thyroxine (T 4 ) and testosterone (along with testicular sialic acid) were quantitated. Histometry and histology of the testis and adrenal glands were also performed. It became evident that a parallel relationship exists between the reproductive phases of the common myna and levels of the hormones E, NE, corticosterone, T 3 , T 4 and testosterone. Considering the ambient climatological conditions, it is suggested that primarily daylength and secondarily humidity control the gonadal cycle of this species.     

Relation between the Adrenals and Thyroid and their Hormones and the Testicular cycle of a Subtropical Avian Species

In order to understand the hormonal interactions throughout the reproductive phases (non-breeding, progressive, breeding and regressive) of a sub-tropical avian species, the male common myna (Acriodotheres tristis), hormones like epinephrine (E), norepinephrine (NE), corticosterone, tri-iodothyronine (T 3), thyroxine (T 4) and testosterone (along with testicular sialic acid) were quantitated. Histometry and histology of the testis and adrenal glands were also performed. It became evident that a parallel relationship exists between the reproductive phases of the common myna and levels of the hormones E, NE, corticosterone, T 3, T 4 and testosterone. Considering the ambient climatological conditions, it is suggested that primarily daylength and secondarily humidity control the gonadal cycle of this species.     

The Pineal Gland,but Not Melatonin,Is Associated with the Termination of Seasonal Testicular Activity in an Annual Reproductive Cycle in Roseringed Parakeet Psittacula krameri

The role of the pineal gland and its hormone melatonin in the regulation of annual testicular events was investigated for the first time in a psittacine bird, the roseringed parakeet (Psittacula krameri). Accordingly, the testicular responsiveness of the birds was evaluated following surgical pinealectomy with or without the exogenous administration of melatonin and the experimental manipulations of the endogenous levels of melatonin through exposing the birds to continuous illumination. An identical schedule was followed during the four reproductive phases, each characterizing a distinct testicular status in the annual cycle, namely, the phases of gametogenic quiescence (preparatory phase), seasonal recovery of gametogenesis (progressive phase), seasonal initiation of sperm formation (pre‐breeding phase), and peak gametogenic activity (breeding phase). In each reproductive phase, the birds were subjected to various experimental conditions, and the effects were studied comparing the testicular conditions in the respective control birds. The study included germ cell profiles of the seminiferous tubules, the activities of steroidogenic enzymes 17β‐hydroxysteroid dehydrogenase (17β‐HSD), and Δ⁵3β‐hydroxysteroid dehydrogenase (Δ⁵3β‐ HSD) in the testis, and the serum levels of testosterone and melatonin. An analysis of the data reveals that the pineal gland and its hormone melatonin may play an inhibitory role in the development of the testis until the attainment of the seasonal peak in the annual reproductive cycle. However, in all probability, the termination of the seasonal activity of the testis or the initiation of testicular regression in the annual reproductive cycle appears to be the function of the pineal gland, but not of melatonin.     

Seasonal Adreno-Cortical Cycle of a Nocturnal Bird,Indian Spotted Owlet Athene brama: Biochemical and Morphological Observations

It is well reported that the environmental factors along with different endocrine stimulus play a crucial role in maintenance of adrenocortical activity in birds. This study is first to report a detailed seasonal activity cycle of adrenal cortex, particu-larly its secretory physiology in a tropical nocturnal bird, Indian spotted owlet Athene brama. The maximum cortical activity having highest glandular mass, glandular free cholesterol, esterified cholesterol profiles, and peak level of corticosterone in plasma coincided with the long day length, highest temperature and increasing amplitude of relative humidity and rainfall of the early summer month, May. Cortical activity declined to minimum level in August when the ecofactors also declined parallely and hence, the birds entered into partial hibernation. The cortical activity progressed slowly throughout the winter (September–March) to reach maximum level in May. Further, the electron microscopic observations of cortical cell morphology strongly supported the above seasonal activity status of the gland revealing a comparatively large number of mitochondria during May than August, along with lipid filled vacuoles during May but not in August. Besides, assessment of gonadal and pineal hormones in relation with seasonal activity of adrenal cortex presented a parallel relationship with gonad while completely inverse relationship with pineal. Therefore, the study concludes that the seasonal adrenocortical activity of this tropical nocturnal bird might be regulated by multiple factors, particularly by the environmental temperature, humidity/rainfall and photoperiod along with the internal factors at least by gonadal and pineal hormones.     

Testicular Expression of NGF,TrkA and p75 During Seasonal Spermatogenesis of the Wild Ground Squirrel (Citellus Dauricus Brandt)

The nerve growth factor (NGF) not only has an essential effect on the nervous system, but also plays an important role in a variety of non-neuronal systems, such as the reproductive system. The aim of this study was to compare the quality and quantity in expression of NGF and its receptors (TrkA and p75) in testes of the wild ground squirrel during the breeding and nonbreeding seasons. Immunolocalization for NGF was detected mainly in Leydig cells and Sertoli cells in testes of the breeding and nonbreeding seasons. The immunoreactivity of TrkA was highest in the elongated spermatids, whereas p75 in spermatogonia and spermatocytes in testes of the breeding season. In the nonbreeding season testes, TrkA showed positive immunostainings in Leydig cells, spermatogonia and primary spermatocytes, while p75 showed positive signals in spermatogonia and primary spermatocytes. Consistent with the immunohistochemical results, the mean mRNA and protein level of NGF and TrkA were higher in the testes of the breeding season than in non-breeding season, and then decreased to a relatively low level in the nonbreeding season. In addition, the concentration of plasma gonadotropins and testosterone were assayed by radioimmunoassay (RIA), and the results showed a significant difference between the breeding and nonbreeding seasons with higher concentrations in breeding season. In conclusion, these results of this study provide the first evidence on the potential involvement of NGF and its receptor, TrkA and p75 in the seasonal spermatogenesis and testicular function change of the wild ground squirrel.Key words: NGF, p75, seasonal spermatogenesis, TrkA, wild ground squirrel     

Seasonal Thyroid Cycle of the Soft-shelled Turtle, Lissemys p. punctata (Bonnoterre)

The current study was undertaken to ascertain the seasonal influence of thyroid activity in female soft-shelled turtles, Lissemys p. punctata. Thyroid gland was studied month-wise throughout the year from relative gland weight, histology, epithelial height, glandular peroxidase activity, and RIA of T₃ and T₄ levels from blood serum and the thyroid gland. The values of all the parameters, except those of T₃ and T₄, were higher during March through May, decreased from June through August and began to rise thereafter (September through February). Whereas T₃ and T₄ levels were highest in May, lower during June to November and began to rise thereafter. The difference in the peaks between T₃ and T₄ levels and other parameters have been explained. The findings suggest that thyroid activity of Lissemys turtles varies seasonally and that seasonal factors like temperature play an important role in influencing thyroid activity in soft-shelled turtles.     

Fluctuation of Aquaporin 1, 5, and 9 Expression in the Pig Oviduct during the Estrous Cycle and Early Pregnancy

Thirteen mammalian aquaporin (AQPs) isoforms with a unique tissue-specific pattern of expression have been identified. To date, 11 isoforms of AQP have been reported to be expressed in female and male reproductive systems. The purpose of our study was to determine the localization and quantitative changes in the expression of AQP1, 5 and 9 within the pig oviduct during different stages of the estrous cycle and early pregnancy. The results demonstrated that AQP1, 5, and 9 were clearly detected in all studied stages of the estrous cycle and pregnancy. AQP1 was localized within oviductal blood vessels. In cyclic gilts, the expression of AQP1 protein did not change significantly between days 10–12 and 14–16 but increased on days 2–4 and 18–20. AQP5 was localized in smooth muscle cells and oviductal epithelial cells. The expression of AQP5 protein did not change significantly between days 10–12 and 14–16 of the estrous cycle but increased on days 2–4 and 18–20. The anti-AQP9 antibody labeled epithelial cells of the oviduct. The expression of AQP9 did not change significantly between days 10–12 and 14–16 of the estrous cycle but increased on days 2–4 and 18–20. In pregnant gilts, expression of AQP1, 5, and 9 did not change significantly in comparison with the estrous cycle. Therefore, a functional and distinctive collaboration seems to exist among diverse AQPs in water handling during the different oviductal phases in the estrous cycle and early pregnancy.     

Sex steroids, growth and condition of Arctic charr broodstock during an annual cycle

Changes in plasma concentrations of sex steroids, growth rate and condition of repeat spawning (3+) male and female Arctic charr were studied throughout an annual reproductive cycle. Individually marked fish (mean weight approx. 500 g) were held under conditions of liberal food supply, constant temperature (4° C) and simulated natural photoperiod (Tromsø, 70° N). Once each month fish were weighed, measured and blood samples taken for steroid analysis. Plasma concentrations of testosterone (T), 11-ketotestosterone (11-KT) and oestradiol-17β (E₂) were determined using radioimmunoassay (RIA). Both male and female fish displayed distinct seasonal changes in plasma concentrations of sex steroids, growth rate and condition. From February (minimal concentrations) to March all sex steroids increased slightly and these elevated concentrations were maintained until May. Thereafter, there was a second, and far more pronounced, increase in plasma steroid concentrations which culminated in peak steroid concentrations in September–October. There was then a rapid decline during the spawning period. In winter, growth rate and condition were generally low, then increased during the spring, reached a peak during the summer, and then declined with the onset of autumn. During spring (March–May), the frequency distributions of plasma testosterone concentrations in both male and female fish were bimodal. The fish of the upper modal group of the distribution had significantly higher growth rates and condition than those in the lower modal group. In summer and early autumn (June–September) the association between T and growth rate changed. Significant negative correlations between T and growth rates were observed in females. There was an increase in endocrine activity, indicated by elevated plasma sex steroid concentrations in March, 7–8 months prior to maturation. It is suggested that this may be one factor influencing the onset of spring growth and energy deposition among maturing charr.     

Photosynthetic Characteristics and the Ratios of Chlorophyll, β-Carotene,and the Components of the Xanthophyll Cycle Upon a Sudden Increase in Growth Light Regime in Several Plant Species*

Among three species, Gossypium hirsutum, Rhizophora mangle, and Monstera deliciosa, which were transferred from low to high growth PFD, only small decreases in the efficiency of photochemical energy conversion were observed in those plants which exhibited an increase in photosynthetic capacity. Leaves of plants which showed no increase in photosynthetic capacity experienced a continuous decrease in photochemical efficiency, accompanied by a more pronounced loss of chlorophyll than that observed in the former group. In all species marked increases in the xanthophyll/β-carotene ratio resulted from small increases in lutein, and several-fold increases in the sum of the three components of the xanthophyll cycle, zeaxanthin, antheraxanthin, and violaxanthin. A strong increase in the level of zeaxanthin was only partially matched by a decrease of violaxanthin to zero, and was further paralleled by a decrease in β-carotene. Antiparallel changes in the sum of zeaxanthin + antheraxanthin + violaxanthin and β-carotene between morning and evening were observed in all species. These diel changes were overlaid on a net increase in β-carotene as well as total carotenoid content in those plants in which photosynthetic capacity increased. In those, however, which exhibited no photosynthetic acclimation upon transfer to high light, a decrease in both β-carotene and total carotenoid content was observed. Rhizophora mangle grown at 100 % seawater exhibited a particularly high capacity for increasing the level of zeaxanthin in response to high light.     

一类生化反应系统极限环的存在唯一性

讨论一类具有二重饱和反应速度的生化反应模型,给出了该系统极限环的不存在性、存在性和唯一性的充分条件,并与具有米氏饱和反应速度的生化模型的定性性质进行比较。     

Testicular development and serum sex steroid profiles during the annual sexual cycle of the male sturgeon hybrid the bester

Testicular development in the adult male F₁ sturgeon hybrid, the bester ( Huso huso L. female x Acipenser ruthenus L. male), was examined monthly in relation to serum sex steroid levels. Spermatogenesis lasted for 1 year, with meiosis generally starting in September and spermiogenesis in November, although there was considerable variation in testicular developmental stages between fish sampled monthly. Testicular development continued, slowly, during the winter months until April. Fish did not exhibit spontaneous spermiation, and phagocytotic activity of Sertoli cells became prominent from May onwards. Androgen levels increased during Spermatogenesis and remained high throughout the pre-spermiation period. In the degeneration stage, 11-ketotestosterone concentrations declined to low levels, while testoster- one levels remained high. The serum concentration of 17,20β-dihydroxy-4-pregnen-3-one was low throughout the reproductive cycle. Based on these results, it is suggested that the time appropriate for induction of final maturation would be from November–December to April when the testes are in the late stage of development.     

Pyrimidine and Purine Analogues,Effects on Cell Cycle Regulation and the Role of Cell Cycle Inhibitors to Enhance Their Cytotoxicity

In anti-cancer treatment, deoxynucleoside analogues are widely used in combination chemotherapy. Improvement can be achieved by rational design of novel combinations with cell cycle inhibitors. These compounds inhibit protein kinases, preventing the cell cycle from continuing when affected by deoxynucleoside analogs. The efficacy is dependent on the site of cell cycle inhibition, whether multiple cyclin-dependent kinases are inhibited and whether the inhibitors should be given before or after the deoxynucleoside analogs. The action of cell cycle inhibition in vivo may be limited by unfavorable pharmacokinetics. Preclinical and clinical studies will be discussed, aiming to design improved future strategies.     

Seasonal Fluctuations in Body Fat and Activity Levels in a Rain-Forest Species of Mouse Lemur,Microcebus rufus

Seasonal fattening in preparation for the dry season followed by torpor characterizes some members of the family Cheirogaleidae, a group of < 600-g nocturnal Malagasy primates. These behaviors are associated with extreme seasonality in dry forests, where most studies have been conducted. I aimed to determine if the brown mouse lemur (Microcebus rufus), a rain-forest species of cheirogaleid, exhibited similar changes. Between January 1993 and May 1994 I conducted a mark-recapture study on Microcebus rufus in the rain forest of Ranomafana National Park. I monitored body weight and tail circumference for body fat fluctuations and inferred changes in activity levels from presence or absence in the traps. Some individuals of both sexes increased body fat and entered torpor as suggested by their absence from traps for at least 1 month of the dry season. Activity was resumed with body weight reduced by 5–35 g, and tail circumference by 0.4–1.2 cm. Population-level analysis supports these results; highest weight and tail circumference values occurred just before and at the onset of the dry season. Other individuals, predominantly male, exhibited no change in body fat or activity level, and some mouse lemurs increased their body fat over the course of the dry season. Age, social status, and individual response may influence seasonal behavioral strategies. Dry and rain-forest species of mouse lemur adopt similar behaviors to cope with environmental stresses. Mouse lemurs resemble nonprimate, small-bodied mammals, in which behavioral changes related to maintaining energy balance occur during seasonally unfavorable conditions.     

Demographic and Spatiotemporal Patterns of Avian Influenza Infection at the Continental Scale,and in Relation to Annual Life Cycle of a Migratory Host

Since the spread of highly pathogenic avian influenza (HPAI) H5N1 in the eastern hemisphere, numerous surveillance programs and studies have been undertaken to detect the occurrence, distribution, or spread of avian influenza viruses (AIV) in wild bird populations worldwide. To identify demographic determinants and spatiotemporal patterns of AIV infection in long distance migratory waterfowl in North America, we fitted generalized linear models with binominal distribution to analyze results from 13,574 blue-winged teal (Anas discors, BWTE) sampled in 2007 to 2010 year round during AIV surveillance programs in Canada and the United States. Our analyses revealed that during late summer staging (July-August) and fall migration (September-October), hatch year (HY) birds were more likely to be infected than after hatch year (AHY) birds, however there was no difference between age categories for the remainder of the year (winter, spring migration, and breeding period), likely due to maturing immune systems and newly acquired immunity of HY birds. Probability of infection increased non-linearly with latitude, and was highest in late summer prior to fall migration when densities of birds and the proportion of susceptible HY birds in the population are highest. Birds in the Central and Mississippi flyways were more likely to be infected compared to those in the Atlantic flyway. Seasonal cycles and spatial variation of AIV infection were largely driven by the dynamics of AIV infection in HY birds, which had more prominent cycles and spatial variation in infection compared to AHY birds. Our results demonstrate demographic as well as seasonal, latitudinal and flyway trends across Canada and the US, while illustrating the importance of migratory host life cycle and age in driving cyclical patterns of prevalence.     

Comparisons of Ectomycorrhizal Colonization of Transgenic American Chestnut with Those of the Wild Type,a Conventionally Bred Hybrid,and Related Fagaceae Species

American chestnut (Castanea dentata [Marsh.] Borkh.) dominated the eastern forests of North America, serving as a keystone species both ecologically and economically until the introduction of the chestnut blight, Cryphonectria parasitica, functionally eradicated the species. Restoration efforts include genetic transformation utilizing genes such as oxalate oxidase to produce potentially blight-resistant chestnut trees that could be released back into the native range. However, before such a release can be undertaken, it is necessary to assess nontarget impacts. Since oxalate oxidase is meant to combat a fungal pathogen, we are particularly interested in potential impacts of this transgene on beneficial fungi. This study compares ectomycorrhizal fungal colonization on a transgenic American chestnut clone expressing enhanced blight resistance to a wild-type American chestnut, a conventionally bred American-Chinese hybrid chestnut, and other Fagaceae species. A greenhouse bioassay used soil from two field sites with different soil types and land use histories. The number of colonized root tips was counted, and fungal species were identified using morphology, restriction fragment length polymorphism (RFLP), and DNA sequencing. Results showed that total ectomycorrhizal colonization varied more by soil type than by tree species. Individual fungal species varied in their colonization rates, but there were no significant differences between colonization on transgenic and wild-type chestnuts. This study shows that the oxalate oxidase gene can increase resistance against Cryphonectria parasitica without changing the colonization rate for ectomycorrhizal species. These findings will be crucial for a potential deregulation of blight-resistant American chestnuts containing the oxalate oxidase gene.