Circannual Variation of Intestinal Cell Proliferation in Bdf1 Male Mice on Three Lighting Regimens

BDF, male mice were studied over a 24-hr span in winter, spring, summer and fall. For three weeks prior to study, one-third of the animals were kept under a lighting regimen of 8 hr light alternating with 16 hr of darkness (LD 8:16), one-third on a lighting regimen of LD 12:12 and a remainder on a lighting regimen of LD 16:8. During each study, subgroups of animals on all three lighting regimens were killed at 4-hr intervals over a 24-hr span. Twenty minutes prior to being killed, the animals received 5yCi of [³Hthymidine/0.2 ml/20 gm of body weight intraperitoneally. The thymidine uptake in the DNA of the colon and of the small intestine were studied as an index of cell proliferation. A circadian rhythm in [³H]-thymiduie uptake in the colon was found and validated by cosinor analysis. This rhythm was similar in acrophase and amplitude in the animals kept on LD 8:16 and LD 12:12. Also in the mice on LD 16:8, there was a statistically significant circadian rhythm of ('HJ-thymidtne uptake in the DNA of the colon during all four seasons. The acrophases of this rhythm, however, varied widely suggesting free running. A circadian rhythm of pHJ-thymidine uptake in small intestine was less consistent. In animals on all three lighting regimens, however, a circannual variation of f'HJ-thymidine uptake in DNA in colon and small intestine was found with the highest uptake during summer. This study indicates that a lighting regimen of LD 16:8 does not reliably synchronize the circadian rhythm of [³H]-thymidine uptake in the colon. It further shows a circannual rhythm of this function in the colon and in the small intestine which persists under three lighting regimens (LD 8:16, 12:12 and 16:8) maintained for three to four weeks prior to being killed.     

Seasonally Dependent Effect of Ectopic Pituitary Grafts on 24-Hour Rhythms in Serum Prolactin and Gonadotropins in Rats

To assess to what extent the presence of an ectopic pituitary differentially affected circulating prolactin (PRL) and gonadotropin levels at different times of the year, rats kept under 12h light, 12h dark (12:12 LD) photoperi-ods and receiving a pituitary graft or a sham operation in summer or winter were examined 3 months later. In both male and female sham-operated rats, a circadian variation in serum PRL levels was found, with an acrophase varying from 21:53h to 00:54h and the mesor and amplitude higher in spring than autumn in males and higher in autumn than in spring in females. After grafting a pituitary, changes in serum PRL related to time of day were no longer observed. In pituitary-grafted male rats killed during spring, serum PRL levels were higher than controls at only a few time points throughout the 24h cycle, whereas in rats killed during autumn, there were no significant differences in PRL levels between grafted and control rats. Pituitary-grafted female rats killed during spring showed serum PRL levels significantly higher than those of sham-operated rats, while in female rats killed in autumn, PRL levels of pituitary-grafted and sham-operated rats did not differ. Significant variations of luteinizing hormone (LH) related to time of day were found in sham-operated male rats only, with acrophases at 23:52h and 00:24h for spring and autumn, respectively, and the mesor and amplitude of the rhythm significantly higher in autumn. Pituitary transplants suppressed 24h variations in circulating LH and depressed its levels during the two seasons examined. As far as follicle-stimulating hormone (FSH), pituitary grafts decreased circulating levels, with the extent of decrease higher during autumn than in spring. The results indicate that some endocrine consequences of the grafting of an ectopic pituitary are dependent on time of year.     

Activity Pattern of Echimyid Rodent Species from the Brazilian Caatinga in Captivity

The activity patterns of two closely related echimyid rodents (spiny rats) of the Brazilian Caatinga were studied. One species, Proechimys [Trinomys] yonenagae, is a fossorial dweller of fixed sand dunes. P. [T.] albispinus, inhabits remnants of the Atlantic rainforest areas. A third species, Trichomys apereoides, collected in granite formations in the Caatinga was also studied. The animals were kept individually in cages under controlled conditions and light-dark cycle of 12:12 h. Data were collect by Scan sampling every 2 h, over 3 days, and were analyzed by Cosinor method. All species were nocturnal. P. yonenagae showed a regular pattern of circadian activity and restricted its activity to subjective night. P. albispinus showed an intermittent pattern of activity, especially in the dark phase. T. apereoides showed a bimodal pattern with high crepuscular peaks of activity. A high level of synchrony was found in the activity among individual P. yonenagae. No sex differences were found in behavioral patterns of either P. yonenagae or P. albispinus. Since the two species of Proechimys share a common ancestor, the differences that were found stress the importance of external selection over circadian rhythmicity.     

Recruitment and mortality of early post-settlement stages of benthic algae

Four transitional life history stages are generally recognized for benthic marine algae. On the basis of differences in size, we propose two more: young germlings and young juveniles. Three of these (spores or zygotes, young germlings, and germlings) are considered early post-settlement (EPS) stages. Many of the available data on recruitment and mortality were not collected with EPS stages specifically in mind, and considerable extrapolation and inference are required to interpret effects on early phases. Data on EPS stages, and grazing in particular, are based on the disappearance of early stages (laboratory or field experiments, including outplantings), on indirect information on mortality from manipulations of grazers or juvenile stages, and combinations of observation and manipulation. We also provide original data on the effects of water motion and canopy sweeping on zygote mortality.

The most notable finding is the variability in, and multiplicity of, factors preventing successful recruitment of early life stages. Six intrinsic and about 17 extrinsic factors and/or processes were reported to affect recruitment and mortality. Grazing, canopy, and turf effects appear to be most important, but less well studied factors such as desiccation and water motion may be as important for early stages. Our review indicates that recruitment is highly variable, even episodic, and that mortality at this period is high. Combined, these elements suggest that chance events during EPS stages may play a large role in survival, and perhaps the evolution of benthic algae.     

罗汉果果实总黄酮的含量变化及其抑菌作用

以30％乙醇溶液作提取剂,在超声波功率250W的条件下进行正交试验,结果表明,超声波辅助提取罗汉果果实中总黄酮的最佳条件为料液比1∶9、提取温度80℃、提取时间40 min,在此条件下总黄酮提取率最高,为2.86％.罗汉果果实在10月上旬至12月下旬的生长成熟过程中,总黄酮的含量变化表现为初期逐渐上升,至12月上旬达到最高值,其后快速下降.抑菌实验表明,罗汉果果实中的黄酮类物质对枯草芽胞杆菌、产气杆菌、藤黄八叠球菌和白色念球菌等革兰氏阳性菌的生长具有较显著的抑制作用,而对大肠杆菌、变形杆菌以及青霉和黑曲霉没有抑制作用.     

Correlation between the morpho-cytohistochemistry of the outer mantle epithelium of Anodonta cygnea with seasonal variations and following pollutant exposure

Seasonal and experimental conditions induce morphological and cytochemical variations in the outer mantle epithelium (OME) of the freshwater bivalve Anodonta cygnea, probably influencing the shell calcification mechanism. In this study, OME samples were taken from untreated animals in autumn, winter, spring and summer as well as from animals exposed to divalent metals (cadmium, chromium, lead, copper and zinc) and pesticides (setoxidim and dimethoate) and observed by light microscopy. The present results showed that OME cells have larger cell volumes and increased amounts of secreted macromolecules during spring and summer than in autumn and winter. This correlates with higher shell calcification rates in spring and summer and lower shell calcification rates in autumn and winter. The experiments showed that incubation with pollutants for 8 months dramatically reduced the cellular volume so that the density of cytoplasmic material appeared higher that in the control samples. The pronounced changes in OME cells suggest a significant decrease in secretory activity following exposure to toxic agents and this has implications for the shell calcification process.     

Fine-root seasonal pattern,production and turnover rate of European beech (Fagus sylvatica L.) stands in Italy Prealps: Possible implications of coppice conversion to high forest

Abstract

The aim of this study was to investigate the possible effects of coppice conversion to high forest on the beech fine-root systems. We compared the seasonal pattern of live and dead fine-root mass (d < 2 mm), production and turnover in three beech stands that differed in management practices. Tree density was higher in the 40-year-old coppice stand than in the stands that were converted from coppice to high forest in 1994 and 2004, respectively. We found that a reduction in tree density reduced the total fine-root biomass (Coppice stand, 353.8 g m^?2; Conversion 1994 stand, 203.6 g m^?2; Conversion 2004 stand, 176.2 g m^?2) which continued to be characterised by a bimodal pattern with two major peaks, one in spring and one in early fall. Conversion to high forest may also affect the fine-root soil depth distribution. Both fine-root production and turnover rate were sensitive to management practices. They were lower in the Coppice stand (production 131.5 g m^?2 year^?1; turnover rate 0.41 year^?1) than in the converted stands (1994 Conversion stand: production 232 g m^?2 year^?1, turnover rate 1.06 year^?1; 2004 Conversion stand: production 164.2 g m^?2 year^?1, turnover rate 0.79 year^?1).     

Poplar woody root proteome during the transition dormancy-active growth

Woody plants living in temperate climates finely regulate their growth and development in relation to seasonal changes; their transition from vegetative to dormancy phase represents an adaptation to their environment. Events occurring in the shoot during onset/release from dormancy have been largely investigated, whereas in woody roots they remain completely unknown. In recent years, we have been interested in understanding the molecular and physiological events occurring in poplar woody root during release from dormancy. Here, we propose the results of a comparative analysis of the proteome of poplar woody root sampled at different time points: T₀ (dormancy condition), T₁ (release from dormancy), and T₂ (full vegetative condition). This study identified proteins that may be involved in the long-term survival of a dormant root or landmarking a specific time point.     

Evidence for the presence of novel β-melatonin receptors along with classical α-melatonin receptors in the fish Rasbora daniconius (Ham.)

Abstract

The effects of melatonin (MT) were examined on the isolated scale melanophores from dorso-lateral (D-L) and band regions of a tropical fish Rasbora daniconius. Our study primarily aimed for further depiction of the signaling receptors involved in MT mediated pigment translocations in the fish. Melanophore Size Index (MSI) was employed as a recording parameter for the responses of melanophores to MT and various antagonists. MT has induced aggregation as well as dispersion in D-L region and aggregation in band region melanophores during summer season. During winter, MT-induced responses were only of aggregatory type in D-L region, while in the band region there was an increase in the sensitivity. The responses of the melanophores to MT were reversible. The aggregation of innervated melanophores induced by MT on the D-L and band regions was partially mediated through the neurotransmitters released under the influence of MT and partially by the specific MT receptors. Luzindole and K185 have completely blocked the aggregatory responses of D-L and band region melanophores. Aggregatory receptors may be of the conventional α-MT type. Dispersion of D-L and band region melanophores induced by MT in the presence of various antagonists and on denervated band region could be the result of activation of β-MT receptors of dispersive nature. Presence of α and β MT receptors is thus indicated in this fish melanophores.