Localization of axillary meristems of short day plantChenopodium rubrum L.

Axillary meristems of short day plantChenopodium rubrum are localized as caulinar, foliar or axillar. The localization of axillary meristems and axillary buds of 14 day old plants varied in similar pattern as in other plant species so far investigated: after several nodes with foliar axillary meristems the caulinar ones were produced. However, unlike in other species, in C.rubrum a very high percentage of caulinar meristem is produced also on the first node. In this case, like in the case of its later differentiation at higher nodes, the formation of caulinar meristem is confined also to the vegetative state. It was found that the caulinary position coincides with higher responsiveness to photoperiodic induction. The developmental significance of such behaviour is discussed.     

ATP concentration in thrombocytes at different stages of ontogenesis]

Intraplatelet ATP levels were measured in rabbits of different ages by the firefly technique. Adult and 7-8 day rabbits platelets proved to contain 8.9 +/- 0.9 muM ATP/10(11) cells and 5.8 +/- 0.7 muM ATP/10(11) cells, respectively. The decreased ATP level in the 7-day rabbits' platelets was not related to the platelet isolation procedure.     

Initiation of axillary and floral meristems in Arabidopsis

Shoot development is reiterative: shoot apical meristems (SAMs) give rise to branches made of repeating leaf and stem units with new SAMs in turn formed in the axils of the leaves. Thus, new axes of growth are established on preexisting axes. Here we describe the formation of axillary meristems and floral meristems in Arabidopsis by monitoring the expression of the SHOOT MERISTEMLESS and AINTEGUMENTA genes. Expression of these genes is associated with SAMs and organ primordia, respectively. Four stages of axillary meristem development and previously undefined substages of floral meristem development are described. We find parallels between the development of axillary meristems and the development of floral meristems. Although Arabidopsis flowers develop in the apparent absence of a subtending leaf, the expression patterns of AINTEGUMENTA and SHOOT MERISTEMLESS RNAs during flower development suggest the presence of a highly reduced, "cryptic" leaf subtending the flower in Arabidopsis. We hypothesize that the STM-negative region that develops on the flanks of the inflorescence meristem is a bract primordium and that the floral meristem proper develops in the "axil" of this bract primordium. The bract primordium, although initially specified, becomes repressed in its growth.     

MISSING FLOWERS gene controls axillary meristems initiation in sunflower

The initiation and growth of axillary meristems are fundamental components of plant architecture. Here, we describe the mutant missing flowers (mf) of Helianthus annuus characterized by the lack of axillary shoots. Decapitation experiments and histological analysis indicate that this phenotype is the result of a defect in axillary meristem initiation. In addition to shoot branching, mutation affects floral differentiation. The indeterminate inflorescence of sunflower (capitulum) is formed of a large flat meristem which produces floret primordia in multiple spirals. In wildtype plants a bisecting crease divides each primordium in two distinct bumps that adopt different fate. The peripheral (abaxial) part of the primordium becomes a small leaf-like bract and the adaxial part becomes a flower. In the mf mutant, the formation of flowers at the axil of bracts is precluded. Histological analyses show that in floret primordia of the mutant a clear subdivision in dyads is not established. The primordia progressively bend inside and only large involucral floral bracts are developed. The results suggest that the MISSING FLOWERS gene is essential to provide or perceive an appropriate signal to the initiation of axillary meristems during both vegetative and reproductive phases.     

Effect of alternating magnetic field on ontogenesis and morphophysiological characteristics of radish plants of different magnetic orientation

Effect of weak horizontal alternating magnetic field (AMF) with a frequency of 50 Hz and intensity of 400 A/m on seed formation and morphophysiological characteristics was investigated in radish (Raphanus sativus L.) plants of major types of magnetic orientation (TMO): North–South (NS) and West–East (WE). AMF retarded the passage through all the stages of ontogenesis; as compared with control material, the next leaves emerged slower, and the transition to formation of flower-bearing stems, budding, flowering, and production of pods and mature seeds was delayed. In plants of NS TMO exposed to AMP, the number of pods and seeds and the weight of seeds decreased, while these characteristics rose in WE TMO. AMF acted as an environmental factor differentiating plants’ response depending on their type of magnetic orientation. Dissimilar response to the magnetic field is associated with their physiological status.     

Correlations of convulsive and hypoxic resistance in rats at different stages of ontogenesis

Hypoxic and convulsive resistances were studied in 3, 7, 14, 21, 40-day-old rats and in adults. Susceptibility to hypoxia was determined in pressure chamber by "lifting" the animals to the altitude of 12,000 metres. Convulsions were caused by intraabdominal injections of corazol. A correlation between hypoxic and convulsive resistances was found from 3 day after the birth. Their indexes were maximum at this period. Similar decrease of hypoxic and convulsive resistances was observed with the growth of the animals. Moreover the reduction in hypoxic resistance was more dramatic and reached its minimum on the 40th day. In grown up animals, resistance to hypoxia was higher, than in 40-day-old rats. Minimum latency period for development of status epilepticus was detected in 21-day-old rats.     

Salinity adaptations in the gastropodsLittorina mandshurica andLittorina squalida at different stages of ontogenesis

Salinity adaptations of the gastropodsLittorina mandshurica andL. squalida were studied at different stages of their life cycles.L. mandshurica exhibited a higher degree of adaptation to variations in salinity thanL. squalida at all developmental stages. Egg masses did not protect embryos from desalination; the larvae inside the egg masses were capable of adapting to diluted seawater. As larvae developed in egg masses, their adaptive capabilities increased. At the time of hatching, the salinity tolerance of larvae differed little, if at all, from that of adults. It is assumed that pelagic egg capsules provide an advantage in the distribution of a species.     

Evaluation of genetic homeostasis in animals at different stages of ontogenesis in the environment

Modern methods of genetic homeostasis assessment in animals are described in the present article. The single gel-electrophoresis test (Comet Assay), micronuclei test, chromosome aberration frequency, and sister chromatid exchanges are reviewed in detail. The questions of test-sensitivity of given methods and principles or their application for genetic homeostasis assessment in wild populations of animals are considered.     

Elusive but not hypothetical: axillary meristems in Wollemia nobilis

BACKGROUND: The branches of Wollemia nobilis are unbranched; however, it has been noted that new branches can form from the distal end of damaged ones, and branches can grow from axillary structures once a terminal strobilus has fallen. Tomlinson and Huggett (2011, Annals of Botany 107: 909-916) have recently investigated the formation of these reiterative branches and stated in the title of their paper that 'Partial shoot reiteration in Wollemia nobilis (Araucariaceae) does not arise from "axillary meristems"'. They go on to state 'Further research may reveal the presence of these elusive, but still only hypothetical, axillary meristems'. RESPONSE: In this Viewpoint, I argue that Tomlinson and Huggett do not refer to previously published information that indicates that axillary meristems are present in Wollemia nobilis branch leaf axils, and that their anatomical methods were probably not optimal for locating and examining these minute structures. Thus, whilst I would agree that the axillary meristems in branch leaf axils of Wollemia nobilis are elusive, I contend that they are not hypothetical.     

Filamentous fungi's cell-wall extraction at different stages of ontogenesis and exploration of their carbohydrate composition

Methods of obtaining cell walls (CW) for specimens of mucoraceous molds and ascomycetic affined fungi are developed at the stage of mycelium and resting cells, or spores. CW purity was assessed by electron microscopy, specific staining methods, scourage control, presence of ribose and desoxyribose, and the comparison of chitin content in whole cells and CW of fungi (a new criteria). The authors discuss the significance of the proposed methods of obtaining pure fractions of CW and of the study of their carbohydrate content for the chemotaxonomy of filamentous fungi.     

Quantitative characteristics of heterochromatin regions in human metaphase chromosomes at different stages of ontogenesis]

The comparative study of C-heterochromatic regions has been provided for 1, 9, 16 and Y chromosomes of 30 human embryonal in vivo lymphocytes of 6-8 gestational weeks (obtained with medical abortions), on the one hand, and in vitro lymphocytes of 100 phenotypically normal newborns, on the other hand. According to the results the heterochromatic regions of 1, 9 and Y are significantly shorter in embryonal chromosomes as compared with lymphocytes of newborns.     

Localization of osteopontin in oviduct tissue and eggshell during different stages of the avian egg laying cycle

The avian eggshell is an acellular bioceramic containing organic and inorganic phases that are sequentially assembled during the time the egg moves along the oviduct. As it has been demonstrated in other mineralized tissues, mineralization of the eggshell is regulated by extracellular matrix proteins especially the anionic side chains of proteoglycans. Among them, osteopontin has been found in the avian eggshell and oviduct. However, its precise localization in the eggshell or in different oviduct regions during eggshell formation, nor its function have been established. By using anti-osteopontin antibody (OPN 1), we studied its immunolocalization in the isthmus, red isthmus and shell gland of the oviduct, and in the eggshell during formation. In the eggshell, osteopontin was localized in the core of the non-mineralized shell membrane fibers, in the base of the mammillae and in the outermost part of the palisade. In the oviduct, OPN 1 was localized in the ciliated epithelial but not in the tubular gland cells of the isthmus, in the ciliated epithelial cells of the red isthmus, and in the non-ciliated epithelial cells of the shell gland. The occurrence of osteopontin in each of the oviduct regions, coincided with the concomitant presence of the egg in such region. Considering the reported inhibitory function of osteopontin in other mineralized systems, together with its main occurrence in the non-mineralized parts of the eggshell and at the outermost part of the shell, suggests that this molecule could be part of the mechanism regulating the eggshell calcification.     

Effect of different environmental factors on the brain during animal ontogenesis

The aim of the work was to follow in rats, mice and dogs effects of different environmental factors in certain postnatal periods on the weight indices of the brain. The following factors influenced the brain development: light deprivation, excess of nutrition during suckling period, excess of information. Changes in weight indices are more pronouned if the time of the effect coincides with that of intensive growth and maturation of the brain structure (N. I. Dmitrieva, 1966). Duration of the effects proportionally increases their influence.     

The rolD oncogene promotes axillary bud and adventitious root meristems in Arabidopsis

The expression of the Agrobacterium rhizogenes rolD oncogene induces precocious floral transition and strong flowering potential in tobacco and tomato. Here, we describe specific developmental effects induced by expression of rolD in Arabidopsis. We show that floral transition, as histologically monitored, occurred in rolD- plants earlier than in wild type, and this was coupled with a premature and enhanced formation of vegetative and reproductive axillary bud meristems. Furthermore, CYP79F1/SUPERSHOOT/BUSHY (SPS), a gene that negatively controls shoot branching in Arabidopsis and involved in glucosinolate metabolism and in cytokinin and auxin homeostasis, was down-regulated in rolD plants. The multiplication of post-embryonic meristems was also observed in the root system, with enhanced adventitious root formation. This result was confirmed by thin cell layer response in vitro, both under hormone-free and standard rooting conditions. However, the formation of lateral root meristems was not affected by rolD expression. Our results show that rolD accelerates and enhances specific post-embryonic meristems in Arabidopsis.     

Different functional and structural properties of lactate dehydrogenase isozymes at different stages of Danio rerio ontogenesis

We studied properties of lactate dehydrogenase isozymes expressed at different stages of Danio rerio ontogenesis. H4-LDH and a minor fraction H3M1 are expressed during embryonic development. The muscle isozyme (M4) appears after the beginning of muscle contractions in the embryo. H4 and M4 isozymes isolated from the heart and skeletal muscle of the adult fish, respectively, show significant differences in terms of Km, activation energy (AE), and inactivation temperature. H4-LDH isozymes isolated from unfertilized eggs, the skeletal muscle of larvae, and the heart of the adult fish differ in Km and activation energy, as well as in inactivation temperature. We propose that these differences may be associated with a ligand interacting with the H4 isozyme at different steps of ontogenesis.