Electron microscopy of developmental stages of tomato spotted wilt virus in plant cells.
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Cytopathogenic Effect, Viral↗
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The carbohydrate content of isolated yolk platelets from early developmental stages of Xenopus laevis.
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Animals↗
Transcription factors that activate the Ultrabithorax promoter in developmentally staged extracts.
We have initiated a biochemical analysis of factors that regulate the expression of the Ultrabithorax (Ubx) homeotic gene during embryogenesis. Transcriptionally active extracts have been prepared from Drosophila embryos at successive stages of development that recreate in vitro the temporal profile of Ubx gene expression during embryogenesis. Multiple sequence-specific transcription factors have been detected that bind to essential cis control elements located upstream and downstream of the Ubx mRNA cap site. The activity of some of these transcription factors varies during embryogenesis, and some are detected in embryonic extracts but not in Drosophila tissue culture cells. One factor, which binds to multiple GAGA DNA sequence motifs in the Ubx promoter, has been purified and shown to activate transcription from this promoter in a binding site-dependent manner. This in vitro analysis should help in understanding how Ubx expression is regulated and provide insight into the processes determining cellular fates during development.
Animals↗
Glucose requirement at different developmental stages of in vitro fertilized bovine embryos cultured in semi-defined medium.
Three experiments were conducted in which 2-cell bovine embryos were prepared from oocytes, obtained from abattoir ovaries, by in-vitro maturation for 22 to 24 hours, followed by exposure to spermatozoa for 8 hours and culture for 40 hours within the cumulus. The cumulus cells were then removed, and the cleaved embryos were cultured for a further 120 hours or longer, in the presence or absence of glucose, pyruvate and lactate. Very few embryos developed in the complete absence of energy substrates. Lactate and pyruvate, alone or combined, supported development to the 8-cell stage, but pyruvate was required to support development to the morula stage (Experiment 1). When present throughout culture or when added at 48 or 96 hours postinsemination, 5.56 mM glucose was detrimental to development (Experiments 1 and 2). However, when added at 120 hours postinsemination, 5.56 mM glucose improved development to the blastocyst and expanded blastocyst stages, compared with no glucose or 11.12 mM glucose (Experiment 3).
Journal Article↗
Nerve growth factor and dexamethasone specify the catecholaminergic phenotype of cultured rat chromaffin cells: dependence on developmental stage.
Antibodies to epinephrine (E) and bovine phenylethanolamine N-methyltransferase (PNMT) have been used to monitor the regulation of the E- and PNMT-immunoreactive chromaffin cell phenotypes by dexamethasone (DEX) and nerve growth factor (NGF). The cells were isolated from 1-, 10- and 30-day-old (D1, D10 and D30) rat adrenal glands and grown for 4 days on a polyornithine substratum. DEX (10(-5)M) supported the survival of 90% of the cells from all postnatal ages studied. In contrast, only 45% (D1), 33% (D10) and 60% (D30) of the chromaffin cells had survived after 4 days in control cultures or when treated with NGF (100 ng/ml). Throughout this study numbers of E-immunoreactive cells were approximately 10% larger than those of cells stained by anti-PNMT antibodies irrespective of the treatments applied. 55% of the cells isolated at D1 and 79% of the cells at D10 were stained by anti-E antibodies. The proportion of E-positive cells was constant in D1 cultures carried for 4 days, while E-immunoreactive cells dropped to 63% in cultures from D10. At D1 and D10 DEX and NGF had opposite effects on the portions of E-positive cells, DEX increasing and NGF decreasing their relative numbers, 66% of the chromaffin cells isolated at D30 displayed E-specific immunoreactivity. DEX caused a significant increase (to 74%), while both NGF-treated and control cultures exhibited a decrease in the relative numbers of E-immunoreactive cells.(ABSTRACT TRUNCATED AT 250 WORDS)
Adrenal Medulla↗
Survival and function of dissociated rat dopamine neurones grafted at different developmental stages or after being cultured in vitro.
The in vitro culture approach was combined with the cell suspension grafting technique to examine whether the maturation of dopamine (DA) neurones in vitro imposed similar limitations on their ability to survive grafting as when they are allowed to develop in situ in the fetus. The functional capacity, survival and growth of DA neurones from 2.5- and 7-day-old cultures, grafted to rats with unilateral 6-hydroxydopamine lesions of the nigrostriatal pathway, was compared with similar grafts freshly prepared from fetal donors of embryonic days 14, 16 and 20. Grafts of freshly dissociated mesencephalic DA neurones, taken from embryonic day 14-16 donors and 2.5-day-old cultures, generally survived well and markedly reduced amphetamine-induced rotational asymmetry in the recipient rats. However, when cultured for 7 days prior to grafting, or when taken from 20-day-old fetuses, the mesencephalic DA neurones survived very poorly and the grafts did not have any functional effects. Plating of aliquots of cell suspension used for grafting indicated that the survival rate of dissociated DA neurones is in the same order of magnitude when grown in vitro (about 2 DA neurones per 1000 cells) as when grafted in vivo to the rat striatum (about 1-5 DA neurones per 1000 cells). When the number of surviving grafted DA neurones was plotted against the behavioural effects of the grafts, a threshold number of around 100-200 DA neurones was found necessary to obtain a marked reduction (greater than 50%) in amphetamine-induced rotational asymmetry. Moreover, the survival of 300-500 DA neurones seemed to produce a 'ceiling effect' beyond which additional surviving DA neurones gave rise to little or no further effect on the amphetamine-induced rotational behaviour.
Animals↗
Adaptive changes in rat striatal preproenkephalin expression and dopamine-opioid interactions upon chronic haloperidol treatment during different developmental stages.
This study was designed to evaluate the effects of a chronic treatment with the classical neuroleptic drug haloperidol on the preproenkephalin (ppEnk) mRNA synthesis and its consequences for opioid and dopamine (DA) receptor-regulated adenylate cyclase in the developing and adult rat striatum. Prenatal exposure to haloperidol (2 mg/kg, 14 days) caused a 40% reduction of striatal ppEnk mRNA levels, but had no consequences for DA-stimulated or Met-enkephalin-inhibited adenylate cyclase activity in striatal slices from embryonic day 21 (E21) foetal brain. Postnatal treatment of rat pups from day 10 (P10) until P23 and adult rats resulted in significant increases of mRNA levels of 8 and 41%, respectively, a clear reduction of D1 DA receptor-stimulated cAMP production and a profound desensitization of delta-opioid receptors inhibitory coupled to adenylate cyclase. Since striatal D2 receptor-mediated inhibition of adenylate cyclase activity, in contrast to its activation through D1 receptors, is not present in the prenatal period, this study indicates that the tonic inhibitory effect of DA on striatal ppEnk mRNA synthesis is dependent on the presence of adenylate cyclase-coupled D2 receptors which gradually develops postnatally and further supports the idea that striatal D1 and D2 DA receptors have bidirectional effects on enkephalin synthesis in this brain area. The adaptive changes in D1 DA and delta receptor-regulated adenylate cyclase activity are discussed in relation to the well-known increase in the locomotor and reinforcing effects of mu-opioid receptor agonists upon chronic neuroleptic treatment.
Aging↗
Murine cortical brain cells are autoantigenic from a distinct developmental stage onwards.
The expression of autoantigens on murine cortical brain cells and their first appearance during development was studied. Autoreactivity was analyzed by weight increase and lymphocyte proliferation in the popliteal lymph node (PLN). Cortical brain cells or defined plasma membrane preparations were injected s.c. without adjuvant into syngeneic recipients. Weak, but significant T cell-dependent PLN enlargement was triggered with brain cells from adult mice. A stronger reaction could be elicited with one defined fraction of purified plasma membranes. The earliest appearance of the antigenic material in the plasma membrane fraction was observed on day 15 after birth. This time point correlates exactly with the completion of the blood-brain barrier in large parts of the central nervous system.
Animals↗
Hemicerebellectomy and motor behaviour in rats. III. Kinematics of recovered spontaneous locomotion after lesions at different developmental stages.
The locomotion of rats with a right hemicerebellectomy (HCb) performed in adulthood was compared by means of kinematic analysis with the locomotion of rats with a similar lesion performed on the first postnatal day. The age at which the animals received cerebellar lesion made a significant difference with respect to the locomotor strategies utilized in adulthood. During stance, neonatal operate rats showed a clear hyperextension of both hindlimbs but not of the forelimbs. Their locomotor posture was characterized by spinal flexion with the head held lower than normal. During swing, they showed a tendency towards 'high stepping'. Their steps were regular and symmetrical but hypometric. Adult lesioned animals displayed a marked extensor hypotonia, ipsilateral to the lesion during stance and a relevant hyperflexion affecting both sides, during swing. Alteration of the interlimb coordination and modified sequence of steps were also observed. Thus, a highly asymmetrical, impaired and unstable locomotion was displayed by this group of animals. The present findings demonstrate the importance of the age-at-lesion factor in determining the motor strategies in the recovery of locomotor function after HCb in the rat. This evidence is discussed in the light of the widespread anatomical remodelling already demonstrated following neonatal, but not adult, HCb in rats.
Aging↗
Proline biosynthesis by Fasciola hepatica at different developmental stages in vivo and vitro.
The ability of Fasciola hepatica to produce proline was assessed by measuring activity of the proline biosynthesis enzyme ornithine-delta-transaminase, and the arginine-dependent production of proline in vitro. This was related to the changes in bile proline of rats during the course of infection. It was found that the total production of proline and total enzyme activity per fluke increased as the fluke increased in size. However, while the specific enzyme activity remained constant throughout development, there was a preferential increase in proline production relative to protein content of the flukes just prior to their migration into the bile ducts. This early amplification of proline production could provide the stimulus to induce hyperplasia in the bile duct in preparation for fluke entry as proline production relative to protein content of fluke dropped markedly after migration into the bile ducts and never again reached the pre-migration level.
Animals↗
Analysis of ecdysteroids in different developmental stages of Hymenolepis diminuta.
Prepatent and patent adult Hymenolepis diminuta from the intestines of rats, H. diminuta eggs recovered from the faeces of rats harbouring patent infections, and infective cysticercoids from the beetle intermediate host were analysed for free and conjugated ecdysteroids. Adult worms and eggs contained both free ecdysteroids and hydrolysable polar conjugated ecdysteroids, with comparatively large amounts of immunoreactive material also being detected following hydrolysis of the possible apolar conjugated ecdysteroid fraction. Free ecdysteroids were not detected in the cysticercoid sample. The concentration of free ecdysteroids in H. diminuta eggs was higher than that detected in the tissues of the adult worms. Ecdysone and 20-hydroxyecdysone were the major identified compounds of the free ecdysteroid fraction, whereas in the hydrolysed polar conjugated ecdysteroid fraction these two compounds were accompanied by 20,26-dihydroxyecdysone. The free ecdysteroid fraction also contained comparatively large amounts of unidentified immunoreactive material.
Animals↗
Different pathways for deoxyguanosine toxicity in T-lymphocytes of various developmental stages.
The basis of the selective cellular immunodeficiency which occurs in patients with purine nucleoside phosphorylase (PNP) deficiency still is not completely understood. We studied the mechanism of deoxyguanosine (dGuo) toxicity in proliferating lymphoid T-cells of different maturation stage, i.e. in T-cells of adult peripheral blood and cord blood and in CD3+ and CD3- subfractions of thymocytes. The mitogen-induced proliferation of T-cells from peripheral blood and cord blood and of CD3+ and CD3- subfractions of thymocytes. The mitogen-induced proliferation of T-cells from peripheral blood and cord blood and of CD3+ thymocytes, as well as the spontaneous proliferation of CD3- thymocytes, are inhibited by dGuo. CD3+ and CD3- thymocytes are significantly more sensitive to dGuo than T-cells from peripheral blood or cord blood. Among the thymocyte subfractions CD3- thymocytes appeared to be extremely sensitive. In all cell types studied, inhibition of proliferation is accompanied by intracellular increases in both guanosine triphosphate (GTP) and deoxyguanosine triphosphate (dGTP) concentrations. By use of the PNP inhibitor 8-aminoguanosine, or the metabolites hypoxanthine or deoxycytidine, the metabolism of dGuo could be selectively directed to the formation of GTP or to dGTP. Based on the pattern of rescue from dGuo intoxication under these different metabolic conditions we conclude that in CD3- thymocytes dGuo toxicity is mediated by dGTP. In all other cell types studied GTP mediates dGuo intoxication. Altogether the results show that during the maturation from immature thymocytes to mature peripheral blood T-cells a shift occurs in the pattern of dGuo toxicity since dGuo toxicity in the former is primarily caused via the dCyd kinase pathway, and in the latter mainly the degradation route is involved. Since in PNP deficiency mature T-cells do occur in the peripheral blood, we must conclude that some cells escape the stage of T-cell maturation in the thymus which is extremely sensitive to dGuo. Furthermore, the results imply that as far as T-cell development in the normal thymus is concerned, survival and death of cells might be regulated by local (deoxy) nucleoside availability.
Adult↗
Effects of acid mist on needles from mature Sitka spruce grafts. Part II. Influence of developmental stage, age and needle morphology on visible damage.
Mature grafts of five Sitka spruce (Picea sitchensis (Bong.) Carr.) clones were exposed to simulated acid mist comprising an equimolar mixture of H(2)SO(4) and NH(4)NO(3) (1.6 and 0.01 mol m(-3)) at pH 2.5 and 5.0. Mist was applied to potted plants growing in open-top chambers on consecutive days, four times a week, at a precipitation equivalent of 1 mm per day. The total exposure to polluted mist was equivalent to three times that measured at an upland forest in SE Scotland. The aim of the experiment was to characterize the response of juvenile foliage produced by physiologically mature grafts (on seedling root stock) and compare it with the behaviour of juvenile foliage on seedlings. Development of visible foliar damage was followed through the growing season. Measurements of needle length, diameter, weight, surface area, surface was weight and wettability were made on current year needles to determine whether particular foliar characteristics increased susceptibility to injury. Significant amounts (> 10%) of visible needle damage was observed on only one of the five clones. Damage was most severe on the clone with the most horizontal branch and needle habit, but over the five clones there was no relationship between angle of branch display and damage. Likewise no combination of needle characteristics (length, width, area, amount of wax) was indicative of potential susceptibility. A comparison with previous acid misting experiments using seedlings suggests that juvenile foliage on physiologically mature trees is equally susceptible to visible injury as juvenile seedling foliage. Data of budburst differed among clones, and in this experiment exerted the over-riding influence on development of injury symptoms. Foliage exposed to a combination of strong acidity and high sulphate concentrations over the few weeks immediately following budburst suffered most visible injury. The absence of significant amounts of visible damage in UK forests probably reflects the general low susceptibility to visible injury of Sitka spruce exposed to acid mist.
Journal Article↗
Interrelationships among epidermal Na-K ATPase, developmental stage and length of Rana catesbeiana tadpoles.
Sodium and potassium activated adenosine triphosphatase (Na-K ATPase) was extracted from the skin of Rana catesbeiana tadpoles and adults. Using carefully staged tadpoles, it was noted that the enzyme level increases two or three stages before there is a perceptible potential difference generated across the skin. The level of non-ouabain-inhibitable ATPase remains constant throughout the life cycle. It was also concluded that Rana catesbeiana tadpoles cannot be reliably staged using length as a key trait.
Aging↗
Fine structure and invasive behaviour of the early developmental stages of Theileria annulata in vitro.
The interaction, in vitro, between bovine peripheral blood lymphocytes and sporozoites of Theileria annulata (Ankara) was studied by light and electron microscopy. Beginning five minutes following incubation, samples were taken for Giemsa-stained smears and glutaraldehyde-fixed pellets, for light and electron microscopy, respectively. Sporozoites of T. annulata measure an average of 0.9 microns long, 0.8 microns broad and possess a limiting unit membrane, the pellicle; a round-to-ovoid, eccentrically situated, non-chromocentric nucleus; double-membraned, tubular, acristate mitochondria; varying numbers of anisocytic, densely osmiophilic and pleomorphic organelles, the rhoptries which together with the polar ring form the apical complex; and numerous, loosely scattered, electron-dense ribosomal particles. As early as 5 min of incubation, sporozoites had made contact with, and penetrated, lymphocytes. Sporozoites consistently attached to the lymphocyte plasmalemma by their basal end, possibly at specific receptor sites. Apparently only a proportion of lymphocytes (up to 40% and more commonly 10-20%) were susceptible. Two subpopulations of the susceptible lymphocytes were observed; one which appeared to have receptor sites localized on one pole of the plasmalemma and the other subpopulation in which the receptor sites were distributed evenly around the plasmalemmal surface. Within individual susceptible lymphocytes, the number of interiorized sporozoites increased from 1 to 3 at 5-10 min to as many as 15 or more parasites at around 60 min of incubation. Theileria annulata sporozoites were interiorized by the invagination of the host cell plasmalemma which remained intact throughout the process but later fragmented. Within 30 min of interiorization, each sporozoite underwent dedifferentiation by the loss of its rhoptries and transformed into a trophozoite. Around 24 h, the trophozoite, a uninucleate, motile and feeding stage of the parasite, developed into a schizont by an acentric, closed mitosis.
Animals↗
Enzyme activity patterns in white and red muscle of the eel (Anguilla anguilla) at different developmental stages.
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Anguilla↗
Neutral protease activities at different developmental stages of Schistosoma mansoni in mammalian hosts.
Neutral protease activities of schistosomula, 20 day old and adult worms of S. mansoni have been studied. 1. The neutral enzymes of the three development stages are able to hydrolyse numerous natural and synthetic substrates. 2. The enzymes of homogenates and saponin CaC12 extracts show significant discrepancies in their specificities, optimum pH activities and in the effects of enzyme inhibitors. 3. A serine protease activity was specific for the schistosomula stage whereas thiol proteinases characterize the later stages of evolution. A metalloaminopeptidase activity was shown at all three stages. 4. Gel filtration chromatography and isoelectric focusing of an adult worm homogenate demonstrated the presence of at least 5 caseolytic and 4 azocollytic neutral activities. Three aminopeptidases, one of which exhibited iminopeptidase specificity were revealed by the same procedure.
Aminopeptidases↗
Isotachophoretic and immunological analysis of venoms from sea snakes (Laticauda semifasciata) and brown recluse spiders (Loxosceles reclusa) of different morphology, locality, sex, and developmental stages.
Sea snake venom: The venom compositions of sea snakes, Laticauda semifasciata, with different scale patterns were analyzed by isotachophoresis. The comparison showed quantitative rather than qualitative differences. Similarly, L. semifasciata venoms of Philippine and Japanese origins differed only in the quantity of certain proteins. Spider venom: 3. Loxosceles reclusa venom apparatus extract is rich in neutral and acidic proteins but contains relatively small quantities of basic proteins. Differences in venom apparatus extract composition between nymph and adult (male or female) were detected by isotachophoresis. The extracts of male and female venom apparatus were very similar. Extracts of venom apparatus of spiders collected in locations separated by 100 miles were the same.
Animals↗