Postnatal development of energy metabolism in the rat brain

The activities of cytochrome c oxidase and F0F1-ATPase as well as the content of cytochromes cc1, aa3, and b were investigated in free brain mitochondria in the course of postnatal development and aging. The results show an increase of Vmax of both enzymes during postnatal development (between day 5 and 30). During the following phase ending at the age of 6 months, a decrease of F0F1-ATPase and cytochrome c oxidase activity occurs. From 6 to 12 months of age the activity of these enzymes did not change. The KM for both enzymes remained unchanged during the whole period observed. The content of cytochromes increased from the low values found in young rats, reached the highest values at around one month, and decreased till the age of 3 months. Later, their content in brain mitochondria did not markedly change. Our results suggest that the metabolic maturation of brain mitochondria differs in several aspects from the same process in other tissues, mainly in the time course. This is probably due to the unique role of neural tissue in the organism.     

Plant species delimitation: A comparison of morphological and molecular markers

Abstract

Species delimitation is fundamental in many areas of biology. Despite its importance, there is no agreement on criteria for species delimitation mostly due to divergence on the point of view adopted by the different biological disciplines. Two main groups of diagnostic characters are commonly used to distinguish species: the traditional morphological ones and the molecular ones. Field species recognition and sampling are generally based on morphological characters, but they can either fail to discriminate species and mask the presence of cryptic species or discriminate different species while in reality there is only one. To overcome this problem it is common to compare clusters obtained on the basis of the observed polymorphism of both characters, and to analyse their agreement. Here we compile a set of studies that have examined species delimitation with both markers. This provides a review of the different morphological and molecular markers, and of the sampling strategy and clustering methodology generally employed to delimitate species. Some conclusions are drawn with regard to species delimitation, when comparing diagnostic morphological and molecular markers.     

Functional regulation of brain pyruvate dehydrogenase: Postnatal development, anesthesia and food-deprivation

The activity of brain pyruvate dehydrogenase complex (PDHC), is regulated by reversible phosphorylation of the alpha subunit of the E1 component (pyruvate dehydrogenase, EC 1.2.4.1) of PDHC. Using an in vitro back-titration assay, we have evaluated the postnatal development of E1 phosphorylation, as well as the effects of acute pentobarbital administration and food-deprivation on cerebral cortical E1 phosphorylation in synaptosomal and free mitochondrial compartments of the albino rat. Between birth and postnatal day 25, the back-titration phosphorylation increased ca 4-fold, with the largest increase occurring between days 15 and 20. The phosphorylation of E1 in the synaptosomal, but not free mitochondrial fraction, was decreased during pentobarbital anesthesia. Following 72 h of food-deprivation, E1 phosphorylation was decreased in both subcellular fractions.

The postnatal increase in E1 back-titration phosphorylation is consistent with and similar in magnitude to previously reported increases in the specific enzymatic activity of PDHC. These results also highlight the potential importance of localized subcellular alterations in mitochondrial metabolism and further validate the back-titration phosphorylation of E1 as a valuable tool for the study of central nervous system PDHC metabolism.     

Postnatal development of the energy supplying enzyme pattern in the rat brain

The activity of seven enzymes connected with energy-supplying metabolism was followed from the second day of life till adulthood (87th day). The enzymes selected were: 1. Triosephosphate dehydrogenase (TPDH), 2. Lactate dehydrogenase (LDH), 3. Glycerol-3-phosphate: NAD dehydrogenase (GPDH), 4. Hexokinase (HK), 5. Malate: NAD dehydrogenase (MDH), 6. Citrate syntase (CS) and 7. 3-Hydroxyacyl Co A dehydrogenase. Although some variations occurred, the enzyme profiles were characteristic of those of the nervous tissue from the second day of life onwards until adulthood and displayed relatively high activities of HK, CS and MDH and low activities of TPDH, LDH, GPDH and HOADH. The activities of all enzymes studied here increased during postnatal development and some reached adult values on the 14th day, that of TPDH on the 27th day and HOADH on the 41st day of life. The activities of MDH and GPDH did not attain the adult values still on the 41st day of life. The anaerobic energy supply capacity seems to increase transiently on the 31st day of life, i.e. at a developmental stage where the resistance against hypoxia is known to increase transiently.     

Postnatal development of morphological and vocal features in Asian particolored bat,Vespertilio sinensis

We studied the postnatal development of morphological and vocal features in a free-ranging population of the Asian particolored bat, Vespertilio sinensis. There were no significant differences in postnatal growth rates between males and females on the basis of morphological changes. Body mass and forearm length followed a linear pattern of growth until 28 days of age at mean growth rates of 0.38 g/day and 1.15 mm/day, respectively and thereafter increased slowly. The length of total epiphyseal gap of the fourth metacarpal–phalangeal joint initially showed a linear increase for up to 16 days, followed by a linear decrease until day 46 at a mean rate of 0.18 mm/day. When forearm length was used in combination with changes in total epiphyseal gap length, we derived reliable age estimation equations for the 1–46 day age range. Of the three nonlinear growth models (logistic, Gompertz, and von Bertalanffy), the von Bertalanffy and logistic equations provided the best fit to the empirical curves for body mass and forearm length, respectively. Studies of vocal development showed that infants could emit short calls as precursors of echolocation calls after birth. Isolation calls and precursors of echolocation calls were both characterized by multiple harmonics. We observed a systematic increase in the value of the starting frequency without a significant change in the terminal frequency over the 3 week period of development. In addition, the duration of isolation calls increased until day 4 and then decreased, whereas, the duration of precursors of echolocation calls decreased continuously to reach a stable level.     

Analysis of allozyme variability in three Plantago species and a comparison to morphological variability

Summary The level of electrophoretic variability in three Plantago species, P. major, P. coronopus, and P. lanceolata, was analyzed in relation to their breeding systems and compared with their morphological variability. From each species several populations were analyzed. The outcrossing P. lanceolata had the highest level of electrophoretic variability and the lowest population differentiation. The inbreeding P. major showed the opposite: a low level of electrophoretic variability and a high population differentiation. P. coronopus, with an intermediate breeding system, had an intermediate level of variability and differentiation. In comparing the species, it appeared that P. coronopus and P. major showed good concordance in the distribution of both kinds of variability, each having only a slightly higher morphological than electrophoretic differentiation between populations. P. lanceolata showed a higher morphological than electrophoretic differentiation between populations. A comparison of populations, within species, revealed good concordance of electrophoretic and morphological variability only within P. coronopus, while some populations of the other two species had relatively lower morphological variability compared with electrophoretic variability.Grassland Species Research Group Publication No. 182     

Postnatal growth patterns in eight species of herons and egrets (Ciconiiformes: Ardeidae)

Avian postnatal growth has received considerable attention and its ecological implications have been deeply analyzed. In this current paper, I describe the patterns of culmen and tarsus growth, as well as of weight gain patterns in eight species of herons and egrets (Aves: Ardeidae) found in the Birama Swamp in Eastern Cuba. Between 1998 and 2006,714 nestlings of the following species were measured every two days: Butorides virescens, Bubulcus ibis, Egretta thula, E. tricolor, E. caerulea, E. rufescens, Ardea alba and Nycticorax nycticorax. Logistic and Gompertz equations were adjusted to data using non-lineal regression models with adult values as the asymptote. For each species, the following were determined and recorded: growth rate, age at inflexion, instantaneous growth rates at each age interval, and time taken to reach 90% of adult size. Reported hatchling sizes were similar in other localities, with a variation coefficient ranging between 10-19%. At hatch, each species exhibited differing sizes relative to adult values. In all cases, Gompertz equations were best fitted to explain more variance and lesser residuals. Rates of weight change and tarsus growth were alometrically related to the log of adult weight. Two main growth processes were identified: a physical extension in dimensions of each measurement reflecting inter-specific morphometric differences, and a lineal increase of the growth period from Green Heron to Great Egret. The Black-crowned Night Heron, Cattle Egret and Reddish Egret exhibited some unique measurement characteristics in comparison to the remaining members of the family. All results support the hypothesis that hypermorphosis, as the main evolutionary process in the microevolution of Ardeidae, is caused by a delayed final moment of growth.     

Postnatal development of the cholecystokinin-gastrin family of peptides in the brain and gut of rat

The average levels of CCK-8- and CCK-like peptides present in aqueous and acidic extracts of the brain of the newborn rat were, respectively, 5.3 and 2.9 pmol/g wet weight. These low levels increased 20- and 10-fold, respectively, so as to attain, at 25–30 days post partum, values comparable to those found in adult brain. There was also a rapid deposition of CCK-gastrin-like peptides in the whole gut between day 20 post coitum and day 10 post partum, when maximal concentrations were attained. Later, less CCK-gastrin peptides than other gut components were accumulated during the progressive weaning of the young rats, so that the average concentrations of CCK-gastrin-like peptides were, at day 30, similar to those observed in adult gut.     

Postnatal development of aminopeptidase (arylamidase) activity in rat brain

Changes in the activities of Leu- and Arg-arylamidase in rat frontal and parietal cortices and the subcortical area (including thalamus, hypothalamus, and striatum) were examined in the 2nd, 4th, 8th, 12th, and 24th weeks of life. Average levels found in the subcortical region were greater than those in the cortical areas. The most marked changes in enzymatic activity in the course of brain development were found in the subcortical structure. Leu-arylamidase activity increased from the 2nd week up to the 8th week, returning to the 2nd week level at the 12th and 24th weeks. The maximum levels of Arg-arylamidase activity were found at the 4th and 8th weeks. These data suggest that proteolytic activity is involved in the postnatal development of rat brain.     

Postnatal development of the dentate gyrus: a karyometric and topographic study.

We have analysed the postnatal development of the nuclear sizes of the granular cells of the dentate gyrus in 5- to 190-day-old male mice. The study was performed in three topographic levels: rostral, intermediate and caudal. Three subdivisions were analysed in each level: suprapyramidal blade, infrapyramidal blade and the transition between them, the angular zone. Additionally, each of these subdivisions was measured in its external and internal layer, separately. Three gradients of postnatal karyometric development can be described: external-to-internal, suprapyramidal-to-infrapyramidal, and caudal-to-rostral, indicating that the external, suprapyramidal and caudal cells show higher karyometric sizes than the other subdivisions. These gradients are related to the ontogenetic gradients of these neurons.     

Postnatal growth and behavioral development of mice cloned from adult cumulus cells

Since the first successful cloning of mammals from adult somatic cells, there has been no examination of the learning or behavior of cloned offspring. The possibility of adverse effects on animals produced through adult somatic cell cloning is high because many natural biological processes are bypassed and DNA from adult cells, which presumably contain mutations, are used. In this study, we compared cloned mice produced by microinjection transfer of cumulus cell nuclei into enucleated oocytes, to control mice that were specifically generated to eliminate confounding factors that are unique to our cloning procedure. Postnatal weight gain of clones was significantly greater than that of controls. Preweaning development observations revealed that first appearance or performance of 3 out of 10 measures was delayed in cloned mice; however, results of subsequent tests of learning and memory, activity level, and motor skills were comparable for both groups. Together, these data suggest that nuclear transfer of adult somatic cell nuclei to produce cloned mice may delay the appearance of a few developmental milestones but it does not adversely affect the overall postnatal behavior of mice. In addition, this procedure may cause late onset of significantly increased body weight in cloned offspring, the cause or causes of which are being further examined.     

The influence of swimming demand on phenotypic plasticity and morphological integration: a comparison of two polymorphic charr species

In northern freshwater lakes, several fish species have populations composed of discrete morphs, usually involving a divergence between benthic and limnetic morphs. Although it has been suggested that swimming demand plays an important role in morphological differentiation, thus influencing habitat selection, it is unclear how it affects reaction norms, patterns in character correlation, and levels of morphological integration. We examined whether swimming demand could induce morphological plasticity in the directions expected under divergent habitat selection, and evaluated its influence on the morphological integration in Arctic charr (Salvelinus alpinus) and brook charr (S. fontinalis), two congeneric species exhibiting conspicuous and subtle resource polymorphism, respectively. We found that changes in morphology were induced by differential swimming demands in both species. The length of the pectoral fin was the character that responded most strongly according to the predicted morphological expectations under divergent habitat selection. High levels of morphological plasticity, relatively low levels of integration, and differences found in the morphological correlation structure among water velocity treatments suggest that constraints on morphological change are unlikely in either species, thus allowing great potential for phenotypic flexibility in both species. The magnitude of character integration, however, was larger for Arctic charr than for brook charr. This latter result is discussed in the light of the differences in the level of polymorphism between the two species in the wild. The results of the present study indicate that swimming demand alone may not be sufficient to generate the polymorphism encountered in nature. Given that both diet and swimming demands can induce morphological changes, it would be important to conduct experiments targeting the interaction between the morphological modules related to trophic and swimming demands.     

Structure trees and species trees: what they say about morphological development and evolution

The evolutionary history of morphological structures generally is equated with that of the taxa that carry them. It is argued here that, analogous to genes, developmental genetic pathways underlying morphological structures may be subject to developmental evolutionary changes that result, for instance, in duplication (serial homology analogous to gene duplication and paralogy). Entities that undergo evolution are expected to be related to each other as a tree. Just as with molecular evolution, "structure trees" and species trees sometimes may be incongruent, with implications for morphological homology concepts. Detection of structure trees through morphological evolutionary analyses may point to an entity that is maintained through evolution, possibly in part because it is a developmentally integrated structure ("individualized"). This idea is illustrated in a morphological evolutionary analysis of leaf primordia. These analyses suggest that leaf primordia in monocots and close relatives are related to each other as a tree and, therefore, are developmentally integrated, evolving entities. Among monocot primordia this tree structure breaks down, and it is concluded that there is no entity, the "monocot leaf primordium." However, one group of primordia is identified within monocots that have uniform characteristics and that are well represented by model species maize and rice. Such analyses of structure trees can facilitate the extrapolation and interpretation of results from molecular developmental and other comparative studies.     

Bovine fibroblast growth factor: comparison of brain and pituitary preparations

Bovine brain and pituitary fibroblast growth factors (FGF) have been compared with regard to their chemical and biological properties. Pituitary and one preparation of brain FGF (Prep A) contain a basic mitogenic activity, which migrates to the same position on electrophoresis in acid pH gels as detected by incorporation of [methyl- 3H]-thymidine into BALB/c 3T3 cells. In contrast, another preparation of brain FGF (Prep B) contains two mitogens, one (20-30%) indistinguishable from the basic components in pituitary and brain (Prep A) FGF preparations and an acidic activity (70-80%), pl 5-6, that migrates more slowly on acid gels, corresponding to the acidic component of brain FGF described previously (Thomas, K. A., M. C. Riley, S. K. Lemmon, N. C. Baglan, and R. A. Bradshaw. 1980. J. Biol. Chem. 255:5517-5520.) In agreement with that report, none of the mitogens comigrates with fragments of myelin basic protein. Pituitary FGF was virtually inactive, brain (Prep A) FGF had a small amount of activity, and brain (Prep B) FGF was highly potent (50% maximal stimulation at 15-30 ng/ml) in stimulating the growth of human umbilical vein endothelial (HUVE) cells. The acidic component of brain FGF, which is much more unstable at pH 8.5 than the basic one, can be protected by reducing agents, whereas the basic constituent of brain FGF as well as pituitary FGF is unaffected by reducing conditions. Thus, brain FGF preparations may contain two distinct mitogenic activities, one that is acidic and contains HUVE cell activity, and a basic mitogen that is similar to and may be identical with pituitary FGF.