Electron microscope study of the changes in the pyriform neurocytes in the mouse cerebellum during protein-calorie deficiency

The changes in the distribution of dark, light and intermediate pyriform neurocytes (Purkinje's cells) in the cerebellum of mice which developed under the conditions of protein-caloric deficiency were assayed from the 10th to the 40th day of mouse life. In the control animals, the number of dark cells was 7 +/- 3%, of intermediate 44 +/- 7%, and that of light ones 49 +/- 7%. Under malnutrition the number of dark cells rose to 26 +/- 5% (P less than 0.01), that of intermediate cells fell to 33 +/- 6% (P less than 0.01), and the number of light cells changed insignificantly (41 +/- 6%, P less than 0.1). Electron microscopy of the ultrastructure of dark cells has disclosed dystrophic and destructive changes in the nucleus and in the main organelles of the cytoplasm. Pronounced astroglial reaction was not infrequently observed around dark cells.     

Morphometric analysis of the pineal complex of the golden hamster over a 24-hour light:dark cycle: I. The superficial pineal in untreated and optically enucleated animals

Morphometric analysis of the superficial pineal gland of intact and blinded golden hamsters was conducted at both the light and electron microscopic level. The volume of the superficial gland was estimated to be 151 X 10(6) micron 3, comprising 90-94% of the total pineal parenchymal tissue. Analysis of structural rhythms in animals maintained under a 14:10 L:D cycle showed significant 24-hr variations in values for pinealocyte nuclei, nucleoli, rough and smooth endoplasmic reticulum, Golgi bodies, dense bodies, and dense-cored vesicles. Peak values for these structures generally occurred at the light:dark interface. These results provide morphological correlates for known rhythmic variations in the synthesis of pineal-gland products. Superficial pineals examined 8 weeks following optic enucleation exhibited a decrease in the volume of pinealocyte nuclei and cytoplasm, while nucleolar size and the amounts of smooth and rough endoplasmic reticulum, Golgi bodies, dense bodies and dense-cored vesicles were enhanced. The latter changes are interpreted as indications of increased synthetic activity by the superficial pineal gland in response to light deprivation.     

The relationship of DNA synthesis to protein accumulation in the cell nucleus

The relationship between DNA synthesis and protein accumulation in cell nucleus and cytoplasm has been investigated by the use of a combination of ultramicrointerferometric and ultramicrospectrophotometric methods. 5-Fluoro-2'-deoxyuridine (FUdR) inhibited DNA synthesis, resulting in inhibition of cell proliferation in G-1 and early S-phase. However, synthesis and accumulation of protein continued in the presence of FUdR, as indicated by a 54% increase in the average dry mass value per individual cell during 18-hour exposure to FUdR; due primarily to protein accumulation in the cytoplasm, the average cytoplasmic dry mass increased by as much as 85%, while the dry mass of the nucleus increased by only 21%. The dry mass values of individual nuclei were well-correlated to the nuclear DNA content throughout the period of exposure to FUdR. In contrast to the continued accumulation of protein in the cytoplasm during inhibition of DNA synthesis, protein accumulation in the nucleus was inhibited. When cells were released from inhibition of DNA synthesis by the addition of 2'-deoxythymidine, the nuclear DNA content and nuclear dry mass increased in near-synchrony, there being some evidence that DNA synthesis was initiated somewhat prior to initiation of increase in nuclear dry mass. Thus, it appears that DNA synthesis (or an increase in nuclear DNA content) is intimately related to the regulation of protein accumulation in the nucleus.     

The Relative Concentration of Solids in the Nucleolus, Nucleus, and Cytoplasm of the Developing Nerve Cell of the Chick

Growing and differentiating nerve cells of the fifth cranial ganglion of the chick embryo were studied by several means. During the period of 70 hours to 11 days of incubation (Hamburger-Hamilton stages 19 to 37) average cell mass increased more than 4.5 times while cells changed from relatively undifferentiated neuroblasts to morphologically characteristic nerve cells with long processes. By making simplifying assumptions about thickness of nucleus and nucleolus, relative to cytoplasmic thickness, it was possible to calculate solute concentration of nucleus and nucleolus relative to that of the cytoplasm from measurements of optical retardations through living cells. Differences in relative solute concentration were observed in nucleolus, cytoplasm, and nucleoplasm in the approximate ratio 1.2:1.0:0.8, respectively. The ratio remained essentially constant during the growth period examined despite the fact that the cell components grow at markedly different rates. This suggests that solid concentrations are physical characteristics of nucleus, nucleolus, and cytoplasm which are maintained even during rapid growth and differentiation. By cytochemical means it was demonstrated that mass increase in the nucleus is not associated with increase in deoxyribonucleic acid. Both ribonucleic acid and protein are in greater concentration in nucleolus and cytoplasm than in the nucleoplasm. Electron microscopy shows interruptions in the nuclear envelope as well as an approximately even distribution of electron density in nucleus and cytoplasm. It is pointed out that consistent differences in solid concentration can exist on either side of the nuclear envelope even though it contains "pores." Implications of these data are discussed.     

Plasma concentrations of testosterone and LH in the male dog

Blood samples were withdrawn every 20 min from 3 conscious intact and 2 castrated mature males during non-consecutive periods of 12 h during the light and dark phases of the lighting schedule (intact dogs) and of 11 h during the light period (castrated dogs). In the intact dogs testosterone concentrations ranged from 0.4 to 6.0 ng/ml over the 24-h period. LH concentrations varied from 0.2 to 12.0 ng/ml. In all animals, LH peaks were clearly followed, after about 50 min, by corresponding testosterone peaks, but no diurnal rhythm could be established. LH concentrations in the castrated dogs were high (9.8 +/- 2.7 (s.e.m.) ng/ml), and still showed an episodic pattern in spite of the undetectable plasma testosterone levels.     

The effects of continuous light and darkness on the activity of monoamine oxidase A and B in the hypothalamus, ovaries and uterus of rats

For assessing monoamine oxidase (MAO-A and -B) activities in the hypothalamus, ovaries and uterus, mature female rats were exposed to either continuous light or dark over 6 weeks. Confirming previous studies, continuous light induced constant estrus in all animals. The majority of animals kept under continuous dark during the six weeks remained mostly in diestrus with estrus appearing sporadically. The endocrinological function of the ovaries was disturbed by continuous light, which resulted in the development of polycystic ovaries, their morphological appearance being not significantly affected by continuous dark. Hypothalamic MAO-A activity was markedly reduced under the influence of both light (p < 0.05) and dark (p < 0.01). The activity of hypothalamic MAO-B was reduced only under the influence of dark (p < 0.01). In the ovaries, no significant differences were detected in either MAO-A or -B activity as a result of these environmental manipulations. In the uterus of rats exposed to continuous light which developed polycystic ovaries, MAO-A activity was significantly lower (p < 0.05) in comparison to either intact controls or rats exposed to continuous dark. These results demonstrate that chronic changes in photoperiodicity may considerably influence MAO-A activity and to a lesser extent MAO-B activity dependent on the tissue studied.     

Diurnal variation in the dopamine level of rat brain areas: effect of sodium phenobarbital

The levels of dopamine in the caudate nucleus, cerebellum, cortex and midbrain were determined every three hours in control rats nd in rats pretreated with sodium phenobarbital over a twenty-four hour period. All animals were adapted for a minimum period of three weeks to an environmental room equipped with a programmed 12 hour dark — 12 hour light illumination cycle. The level of dopamine was highest during the dark phase and lowest during the light phase of the photoperiod in all the brain areas studied. Sodium phenobarbital pretreatment increased dopamine level in all the brain areas studied at most times, particularly during the dark phase and enhanced the circadian rhythmicity of dopamine levels in the cortex, cerebellum and midbrain.     

温度与光周期对白头鹎体质量、能量收支和消化道形态的影响

温度与光周期是环境季节性变化的最直接表现因子及时间变化指示标志,对动物的形态、生理及行为产生重要的影响.本文以白头鹎为研究对象,探讨了不同温度与光周期对其体质量、能量收支和消化道形态的影响,分析了能量收支与消化道形态特征的关系.将28只白头鹎(12雄16雌)分为4组:暖温长光组(30℃,16 L8 D;3雄4雌)、暖温短光组(30 ℃,8 L16 D;3雄4雌)、低温长光组(10 ℃,16 L8 D;3雄4雌)和低温短光组(10 ℃,8 L16 D;3雄4雌).结果表明: 低温与短光照可促进白头鹎的体质量、摄入能及同化能明显增加,同时温度与光周期的交互作用对白头鹎的摄入能及同化能影响显著.低温条件下,胃、小肠、直肠及总消化道的湿质量及干质量明显增加.残差分析表明,小肠与总消化道的长度及干质量与摄入能和同化能显著相关.表明低温与短光照下白头鹎通过增加体质量、能量摄入和改变消化道形态来应对严酷的环境条件.     

Changes in the size of the nucleoli of the Purkinje cells in the canine cerebellum in the postresuscitation period

The changes in the size of Purkinje cell (PC) nucleolus in the lateral and medial cerebellum zones were studied in dogs with different degree of neurologic status recovery after clinical death of various etiology and duration. PC always possess one nucleolus in the control and experimental groups. In the case of complete neurologic status recovery of animals the area of PC nucleolus increases in both zones studied, irrespective of the cause of clinical death. In the case of neurologic disorders the increase in PC nucleolus area is clearly expressed only in the medial zone of the cerebellum, being insignificant in the lateral zone. It is suggested that adaptive characteristics of PC are distinct in the two compared zones, which leads to greater PC vulnerability in the lateral zone during deep hypoxia.     

Cardenolide biosynthesis in light- and dark-grown Digitalis lanata shoot cultures

Shoot cultures of the cardenolide-producing species Digitalis lanata Ehrh. accumulated up to 0.6 μmol cardenolides per g dry mass when cultivated under continuous white light. After transfer to permanent dark, the cardenolide content of cultured shoots gradually decreased and reached non-detectable levels after 12 weeks. After transfer back to light conditions, cardenolides started to accumulate and reached the levels of light-grown controls after 4 weeks. Radiolabelled pregnenolone and progesterone were incorporated into cardenolides in both green light-grown and white dark-grown shoots. It was thus established that cardenolides are synthesised de novo in chloroplast-free tissues without apparent cardenolide accumulation, indicating that these compounds are efficiently turned over in the dark and that tissue differentiation, but not intact chloroplasts, is essential for cardenolide formation. The time course of two late anabolic enzymes of cardenolide metabolism, acetyl-CoA:digitoxin 15′-O-acetyltransferase (DAT, EC 2.3.1.-) and UDP-glucose:digitoxin 16′-glucosyltransferase (DGT, EC 2.4.1.-) was established during transfer of shoots from light to dark and vice versa. Only DAT was affected and was not measurable any more under dark conditions. The DGT may not be down-regulated because of its important, maybe even vital, role as an enzyme providing the vacuolar storage forms of cardenolides. Two catabolic cardenolide-specific enzymes, lanatoside 15′-O-acetylesterase (LAE, EC 3.1.1.6.) and cardenolide 16′-O-glucohydrolase I (CGH I, EC 3.2.1.21), were also investigated and it was demonstrated that CGH I is inactive in dark-grown shoots. These observations indicate that CGH I is not involved in cardenolide degradation in situ, but may instead play a role in cardenolide remetabolisation and activation after wounding or in developmental programs.     

An immunocytochemical study of effects of light deprivation on prolactin cells in the adenohypophysis of the golden hamster.

Population ratio and morphology of prolactin cells were studied by employing immunohistochemical methods in the adenohypophysis of normal and experimental golden hamsters of both sexes at 16 weeks of age. Prolactin cells occupied 29% of the total adenohypophyseal cells in the intact males exposed to 14/10 h light/dark schedule. After stimulation of the pineal activity by binding or exposure of males to continuous darkness for eight weeks, prolactin cells became atrophic and were reduced in population to 17% and 13%, respectively. Pinealectomy prevented to some extent the effects of the above treatments; thus, prolactin cells constituted 27% in the pinealectomized and blinded hamsters, and 19% in the pinealectomized and darkness-treated group; and their morphology was comparable with that of the intact controls. Prolactin cells in the normal females were apparently larger in size and more numerous as compared with those of the normal males, comprising 47% of cell population in the anterior pituitary. In response to light deprivation, prolactin cells were atrophic with a diminished cytoplasm and decreased in cell number as reflected in the population ratio of 27% in the blinded and 21% in the darkness-treated groups. In pinealectomized females combined with binding or darkness-treatment, prolactin cells contained an abundance of secretory granules in the cytoplasm and maintained the population ratio comparable to that in the intact females. The present study revealed that light deprivation exerts an inhibitory effect on the secretory activity of prolactin cells and also causes hypoplasia of prolactin cells in the hamster adenohypophysis, the effects being mediated by the pineal gland.     

The chicken trigeminal ganglion. I. An anatomical analysis of the neuron types in the adult

An anatomical analysis of the chicken trigeminal ganglion was made using light microscopy on specimens prepared by usual chemical fixation or freeze-drying methods and by electron microscopy. Two types of neurons were consistently seen, dark and light cells. Dark cells contained a dense cytoplasm with Nissl substance distributed evenly throughout, whereas light cells had a less dense cytoplasm containing clumps of Nissl substance. The Nissl bodies in light cells contained only a few small cisternae of granular endoplasmic reticulum as compared with many stacked cisternae in Nissl bodies of dark cells. The ratio of dark to light cells was approximately 62:38 in all regions of the ganglion. Dark cells were consistently smaller than light cells. In the seven-day old chick, the mean diameters of the dark and light neurons were 21.4 μ and 29.5 μ respectively; in the adult the values were 29.9 μ and 39.7 μ respectively. It is concluded that the dark and light cells belong to two distinct neuronal cell populations.     

Ketamine-xylazine anaesthesia in the Djungarian hamster (Phodopus sungorus)

The combination of ketamine-xylazine was assessed as a surgical anaesthetic in Djungarian hamsters acclimatized to both long (16 h light: 8 h dark) and short (8 h light: 16 h dark) photoperiods. It was concluded that 50 mg/kg of ketamine with 10 mg/kg of xylazine or 100 mg/kg of ketamine with 5-10 mg/kg of xylazine when given together by intraperitoneal injection was a satisfactory general anaesthetic. Two hundred mg/kg of ketamine with 10 mg/kg xylazine caused death in 13 of 24 animals. There were no clinically significant effects on depth of anaesthesia due to photoperiod.     

Application of laser interference microscopy (LIM) for investigation of the protective effect of prolyl-glycyl-proline (Pro-Gly-Pro) on mast cells

The effect of peptide prolyl-glycyl-proline (Pro-Gly-Pro) on morphometric parameters of mast cells upon their activation by compound 48/80 or synacten was investigated. Cell image, obtained by the method of laser interference microscopy (LIM), is a distribution of the optical path difference of light (OPD). It evaluates the changes of the individual components of cytoplasm (maxOPD) and the total distribution of OPD (“dry mass”). The changes of “dry mass” in cytoplasm correlate with the changes of the secreted histamine amount (?0.86). Preliminary incubation of mast cells with Pro-Gly-Pro (6 × 10^?5 M) did not change the area, the state of the individual components of the cytoplasm (nucleus) and “dry mass” (histamine vesicles) in cells. The “dry mass” (histamine vesicles) and maxOPD decreased while the release of histamine increased upon the activation of mast cells by compound 48/80 (0.02 mg/mL). Preincubation of cells with Pro-Gly-Pro had no effect. Activation of cells by synacten (2 and 20 μM) led to the increase of the cell area and the reduction of maxOPD and “dry mass” (histamine vesicles). Preincubation of the cells with Pro-Gly-Pro prevented these changes. So, the protective effect of Pro-Gly-Pro was observed in the case of the activation of mast cells by synacten but not by compound 48/80.     

Reassembly of anAcetabularia mediterranea cell from the nucleus,cytoplasm, and cell wall

Summary A. mediterranea cells capable of full morphogenesis were reassembled from nuclei, cytoplasm, and cell wall fraction.Reassembly was performed stepwise with the recombination of cytoplasm and cell walls and finally a nucleus was implanted.Reassembly of anucleate cells was carried out by means of retransplantation of their own cytoplasm or transplantation of cytoplasm from another cell. Combinations between cytoplasm and cell walls of dark or light maintained cells were prepared. The nuclei were always transferred from light maintained cells.     

Dim light at night increases body mass of female mice

During the past century, the prevalence of light at night has increased in parallel with obesity rates. Dim light at night (dLAN) increases body mass in male mice. However, the effects of light at night on female body mass remain unspecified. Thus, female mice were exposed to a standard light/dark (LD; 16?h light at ～150?lux/8?h dark at ～0?lux) cycle or to light/dim light at night (dLAN; 16?h light at ～150?lux/8?h dim light at ～5?lux) cycles for six weeks. Females exposed to dLAN increased the rate of change in body mass compared to LD mice despite reduced total food intake during weeks five and six, suggesting that dLAN disrupted circadian rhythms resulting in deranged metabolism.     

Electron microscopic and autoradiographic study of the synthesis of RNA in dark and light adrenal cells

The experiments on mice, who were intraperitoneally injected 5-3H-uridine at a dose of 100 microCi/g, have established that dark adrenal cells are distinct in faster incorporation of the labeled precursor and translocation of the newly-synthetized RNA from the nucleus into the cytoplasm, as compared to light cells. RNA synthesis and translocation into the cytoplasm are more intensive in cells of the glomerular zone. In cortical substance cells, as compared to adrenal cells, the newly-synthetized RNA translocation into the cytoplasm and RNA degeneration are accelerated.     

Chloroplast signalling in the light induction of nuclear HSP70 genes requires the accumulation of chlorophyll precursors and their accessibility to cytoplasm/nucleus

Chlorophyll precursors Mg-protoporphyrin IX and its monomethylester are candidates for plastid-derived molecules involved in light signalling from the chloroplast to the nucleus. The pool sizes of these two Mg2+-containing porphyrins and of protoporphyrin IX transiently increased upon a shift of Chlamydomonas cultures from dark to light. This increase coincided with the accumulation of mRNAs encoded by the nuclear genes HSP70A and HSP70B. Analysis of a mutant (brs-1), previously shown to be defective in the light induction of these genes, revealed high levels of protoporphyrin IX but no light-induced increase in the levels of Mg2+-containing porphyrins. Inhibitors of cytoplasmic protein synthesis prevented both the light-induced rise in pool levels and induction of the HSP70 genes. Similarly, pre-gametes, intermediates of sexual differentiation, lacked both responses to light. The block in light induction of the HSP70 genes in inhibitor-treated cells and in pre-gametes could be circumvented by the exogenous addition of Mg-protoporphyrin IX in the dark. This suggests an essential role for light-induced Mg-protoporphyrin IX accumulation in this chloroplast-to-nucleus signalling pathway. However, accumulation of this porphyrin in the dark - presumably in the chloroplast - did not result in induction. A second crucial role for light in this signalling pathway is postulated which makes this plastidic compound accessible to the cytoplasm/nucleus where the downstream signalling pathway may be activated.     

Increased content of zinc and iron in human cataractous lenses

The purpose of the study was to examine the zinc and iron content of human lenses in different types of cataract and to investigate the possible influence of diabetes on the zinc and iron content of the lens. Iron and zinc of 57 human lenses (28 corticonuclear cataracts and 29 mature cataracts with a mean age of 70.6±16.1 and 74.7±11.1 yr, 41 nondiabetics and 16 diabetics) were determined by atomic absorption spectroscopy. The zinc content of human lenses was significantly increased in mature cataracts compared to corticonuclear cataracts (0.51±0.33 vs 0.32±0.20 μmol/g dry mass, p=0.012). The iron content of mature cataracts was also higher than in corticonuclear cataracts (0.11±0.09 vs 0.07±0.05 μmol/g dry mass, p=0.071). Furthermore, a significant increase of the lens zinc content could be observed with increasing lens coloration (light brown 0.33±0.17 vs dark brown 0.52±0.35 μmol/g dry mass, p=0.032). Diabetic patients seem to have both increased zinc and iron contents in the lens compared to nondiabetic subjects (zinc: 0.45±0.42 vs 0.40±0.22 μmol/g dry mass; iron: 0.12±0.10 vs 0.08±0.05 μmol/g dry mass). These data suggest a possible influence of the lens zinc and iron content on the development of lens opacification. Especially advanced forms of cataract and dark brown colored lenses show significantly increased zinc and iron content.     

Abscisic acid mimics effects of dehydration on area expansion and photosynthetic partitioning in young soybean leaves

Abstract. Leaf area expansion, photosynthetic carbon dioxide uptake and leaf dry mass accumulation were compared for expanding leaves of well-watered soybean ( Glycine max [L.] Merr.) plants, mildly dehydrated plants and well-watered plants treated with abscisic acid (ABA). Both ABA treatment and dehydration reduced area expansion in the light and over a 24 h period without decreasing the photosynthetic rates of expanding leaves. Dry mass accumulation during the light was less in ABA-treated and water-stressed leaves than in control leaves, with no differences among treatments in leaf mass per unit of area. ABA treatment and water stress both increased export of carbon from expanding leaves in the light. ABA applied near the end of the light period also increased export of carbon during the following dark period. However, it is unlikely that decreased availability of photosynthate caused slow expansion in the ABA and dehydration treatments, because expansion rates were not slowed in plants kept in dim light, even though photosynthetic rates and dry mass accumulation rates were greatly reduced. The data suggest that ABA may mediate the effects of mild dehydration on leaf area expansion and partitioning of photosynthate.