Menstrual-cycle phase and sexual behavior in semi-free-ranging stumptail macaques (Macaca arctoides)

The sexual behavior and female reproductive cycles of a group of island-dwelling stumptail macaques (Macaca arctoides)were monitored over a 6-month period, yielding 530 observation hr and 268 copulations. Compared to nondominant males, the dominant male copulated at a relatively high rate throughout the cycle, but largely with one high-ranking female. The non-dominant males copulated most frequently at midcycle. Female presenting was highest at midcycle, but only to the dominant male. Cross-study discrepancies may be due to different observation methods and restricted environmental conditions that mask female-initiated sexual behavior. The more naturalistic setting of this study allowed for a fuller expression of proceptivity. Contrary to some previous conclusions, present findings suggest that both hormonal and socioenvironmental factors influence the patterns of sexual behavior found in stumptail macaque colonies.     

Stimulation of Inositol Incorporation into Lipids of PC 12 Cells by Nerve Growth Factor and Bradykinin

The effects of bradykinin (BK) and lithium on the phosphatidylinositol cycle were examined in PC12 cells cultured for 20 h in the presence [PC12(+)] or in the absence [PC12(-)] of nerve growth factor (NGF). BK (1 microM) induced a small stimulation of the incorporation of myo-[2-3H]inositol into the lipids of PC12(-) cells and a three- to fourfold stimulation of such incorporation into the lipids of PC12 (+) cells. About 15 h of incubation with NGF and greater than 10 min of incubation with BK were needed for maximal stimulation of inositol incorporation by BK. In the presence of 25 mM LiCl, BK stimulated the inositol monophosphate levels nine-fold in PC12 (-) and 30-fold in PC12 (+) cells. After incubation for 20 h with NGF, an increased binding of [3H]BK to the PC12 (+) cells was observed at 4 degrees C. Exposure of the cells for 30 min to 25 mM LiCl enhanced the effect of BK on the inositol incorporation into total inositol lipids, especially in PC12(+) cells. In these cells, LiCl in the presence of BK also increased several-fold the intracellular levels of inositol bisphosphate and inositol trisphosphate.     

How photoperiod influences body temperature selection in Lacerta viridis

Summary European green lizards, Lacerta viridis, show a distinct annual cycle in their day and nighttime selected body temperature (T _b) levels when monitored under natural photoperiod. The amplitude between daily photophase and scotophase temperatures varies throughout the year. Highest body temperatures with smallest day/night variation are selected from May through July. Throughout fall, the difference between day and nighttime selected T _b levels increases. Lizards inevitably enter a state of winter dormancy which terminates daily rhythmicity patterns. Under natural photoperiodic conditions, cessation of dormancy occurs spontaneously by mid-March, regardless whether high temperatures are available or not. Lacerta viridis respond to an artificial long photoperiod (16 h light, 8 h dark) at all times of the year with modifications in both diel patterns and levels of selected T _b to summer-like conditions. When, however, the natural photoperiod at different phases in the annual cycle is held constant for six to eight weeks, T _b selection of Lacerta viridis also remains stable at the level corresponding to the prevailing photoperiod. These results implicate that the photoperiod is a more prominent Zeitgeber for seasonal cueing of temperature selection than has been surmised in the past. Further, we suggest that the large variations recorded in daily T _b cycles do not imply that this lizard is an imprecise thermoregulator, but rather indicates an important integral process necessary for seasonal acclimatization.     

用免疫荧光技术研究细胞周期中核基质的分布变化

本文利用含有抗核基质自发抗体的硬皮人血清,以小鼠艾氏腹水癌细胞为材料,用间接免疫荧光染色的方法,追踪了对应核基质抗原在细胞周期中分布的变化。结果显示,在末期和间期之间存在一个核基质抗原从细胞质向细胞核内转移的过程。由于这一过程是通过核膜进行的,从而提示核基质结构可能有解聚和再聚合的行为。用酶化学结合间接免疫荧光染色的方法,初步研究了抗原的化学性质。染色形态的比较研究显示所用血清中可能含有不同于以前发现的、抗新的核基质抗原的自发抗体。     

The X-ray induced G2 arrest in mouse eggs: a maternal effect involving a lack of polypeptide phosphorylation

Summary In some strains of mice, eggs when X irradiated during the pronuclear stage, undergo a mitotic block in the G₂ phase of the first cell cycle and cleave when the second division takes place in controls. The importance of this effect varies considerably with the strain and depends exclusively on the maternal genotype. In previous work, two-dimensional electrophoresis showed that eggs blocked at the one-cell stage after irradiation, undergo the same modifications in polypeptide synthesis as two-cell controls of the same age, except at the time of normal first mitosis, where three polypeptide sets of 30, 35 and 45 kDa appear only in cleaving controls. In the present study, we have found phosphorylations in dividing controls, on polypeptides of 30, 35 and 45 kDa. These phosphorylations are not seen in blocked irradiated eggs.     

A hypothesis on p34cdc2 sequestration based on the existence of Ca(2+)-coordinated changes in H+ and MPF activities during Xenopus egg activation [corrected]

The entry into, and exit from, mitosis are controlled by a universal M-phase promoting factor (MPF) composed of at least p34cdc2 and a cyclin. Embryonic systems are convenient for studying the association and dissociation of the active MPF complex because oocytes and eggs are naturally arrested at a specific point of the cell cycle until progression to the next point is triggered by a hormonal signal or sperm. In amphibians, eggs prior to fertilization are arrested at metaphase 2 of meiosis due to the presence of a stabilized MPF complex. Fertilization (egg activation) produces a transient increase in intracellular free Ca2+, a propagating Ca2+ wave, that specifically triggers the destruction of cyclin, leading to MPF inactivation and entry into the first embryonic inter-phase. We have recently shown that intracellular pH (pHi) variations in amphibian eggs, a large increase at fertilization and small oscillations during the embryonic cell cycle, were temporally and functionally related to the corresponding changes in MPF activity. In addition, the recent finding that the pHi increase at fertilization in Xenopus eggs is a propagating, Ca(2+)-dependent pH wave which closely follows the Ca2+ wave, together with the absence in the egg plasma membrane of pHi-regulating systems responsible for that pHi increase, suggest the existence of cortical or subcortical vesicles acidifying in the wake of the Ca2+ wave, thus producing the pH wave.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of cyclic AMP and butyrate on cell cycle,DNA, RNA,and purine synthesis of cultured astrocytes

Dibutyryl cyclic monophosphate (dBcAMP) has been shown to inhibit growth, and alter the morphology of astrocytes. However, the potential contribution of its hydrolytic product, butyrate, in inducing some of the changes that have been attributed to dBcAMP, is not clear. DNA, RNA, and purine synthesis were therefore studied in primary astrocyte cultures after 24 hours of exposure to varying concentrations of butyrate, dBcAMP, and agents that increase intracellular cAMP levels. Progression of cells through cell cycle was also studied by flow cytometry. Dibutyryl cAMP partially arrested cells in Go/G1 phase of cell cycle while sodium butyrate increased the percentage population of cells in G2/M phase. DNA synthesis and de novo purine synthesis were inhibited after treatment with dBcAMP, sodium butyrate, and various drugs that increase intracellular cAMP levels. RNA synthesis was increased with cAMP but was not affected by sodium butyrate. Our study shows that at millimolar concentrations, butyrate is capable of altering the cell cycle and inhibiting DNA synthesis in primary astrocyte cultures, in a manner that is similar although not identical to the effects of dBcAMP.     

The annual reproductive cycle of the freshwater mussel Dreissena polymorpha Pallas in lakes

Summary The annual development of the gonads of Dreissena polymorpha was studied at three sampling sites in two lakes over 3 and 1 1/2 years, respectively. A resting stage occurred after the last spawning in summer/autumn. Oogenesis (accompanied by multiplying segmentation of the oogonia and early growth processes of its oocytes) restarted in specimens at least 1 year old at low temperatures (below 10° C) during winter and early spring. At one location (Fühlinger See) the onset of the spawning season was correlated with an increase of water temperatures above 12° C. At 2 m depth, two main spawning periods in May and August were normally recognized, the first at temperatures of 12–16° C, the second at 16–21° C. It was clearly demonstrated for the first time in Dreissena polymorpha that the oocytes became mature in successive cohorts within one gonad. A female mussel may spawn several times during the reproductive season. At 9 m depth, the onset of spawning also started at about 12° C; this occurred in late summer, with two spawning periods within 1 month at a temperature range of 12–16° C. At another location (Heider Bergsee) the size of the gonads and the oocytes was reduced during April of both years studied, when food supply was low simultaneously with rapidly rising water temperatures in this shallow lake. There was no spawning period during spring. The major spawning period was delayed until July (temperatures 19–22°C). This shows (1) the synchronizing influence of low winter temperatures on the annual reproductive cycle and (2) a temperature threshold of at least 12° C for the start of the spawning processes. The results are discussed with regard to the geographical limits of further spread of Dreissena polymorpha.     

Phosphorus availability under alley cropping and mulched and unmulched sole cropping systems in Costa Rica

Phosphorus availability was measured in soils under five cropping systems: alley cropping with Erythrina poeppigiana, alley cropping with Gliricidia sepium, sole cropping with Erythrina poeppigiana mulch applied, sole cropping with Gliricidia sepium mulch applied, sole cropping with no mulch. The following parameters were measured: 1) plant-available soil P assessed by P uptake of maize and bean bioassay plants; 2) phosphate desorbable by anion exchange resin; 3) adsorption of added P into isotopically exchangeable and non-exchangeable pools.In the bioassay, P uptake of beans declined in the order: mulched sole-cropped>unmulched sole-cropped>alley-cropped soils. For maize the relative uptake was: mulched sole-cropped>unmulched sole-cropped = alley-cropped soils. These results suggest trees had not incorporated a significant quantity of P into the system after seven years and, probably, there was a decrease in available soil P due to the sequestration of P in the tree biomass. Potentially resin-desorbable P was higher in alley-cropped and mulched sole-cropped soils than in unmulched sole-cropped soils. The adsorption and desorption of added P into and from exchangeable and non-exchangeable pools did not differ between alley-cropped and unmulched sole-cropped soils.Crop yield and crop N, P and K uptake were all higher in the alley crops than in the unmulched sole crop. The supply of P to the crop under alley cropping seems to be dependent on P cycled and released from the mulch. The P cycle in alley cropping appears to be self-sustaining at least under conditions of moderate P fertiliser input.