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PubMed2005

Dynamics of storage reserve deposition during Brassica rapa L. pollen and seed development in microgravity.

Pollen and seeds share a developmental sequence characterized by intense metabolic activity during reserve deposition before drying to a cryptobiotic form. Neither pollen nor seed development has been well studied in the absence of gravity, despite the importance of these structures in supporting future long-duration manned habitation away from Earth. Using immature seeds (3-15 d postpollination) of Brassica rapa L. cv. Astroplants produced on the STS-87 flight of the space shuttle Columbia, we compared the progress of storage reserve deposition in cotyledon cells during early stages of seed development. Brassica pollen development was studied in flowers produced on plants grown entirely in microgravity on the Mir space station and fixed while on orbit. Cytochemical localization of storage reserves showed differences in starch accumulation between spaceflight and ground control plants in interior layers of the developing seed coat as early as 9 d after pollination. At this age, the embryo is in the cotyledon elongation stage, and there are numerous starch grains in the cotyledon cells in both flight and ground control seeds. In the spaceflight seeds, starch was retained after this stage, while starch grains decreased in size in the ground control seeds. Large and well-developed protein bodies were observed in cotyledon cells of ground control seeds at 15 d postpollination, but their development was delayed in the seeds produced during spaceflight. Like the developing cotyledonary tissues, cells of the anther wall and filaments from the spaceflight plants contained numerous large starch grains, while these were rarely seen in the ground controls. The tapetum remained swollen and persisted to a later developmental stage in the spaceflight plants than in the ground controls, even though most pollen grains appeared normal. These developmental markers indicate that Brassica seeds and pollen produced in microgravity were physiologically younger than those produced in 1 g. We hypothesize that microgravity limits mixing of the gaseous microenvironments inside the closed tissues and that the resulting gas composition surrounding the seeds and pollen retards their development.

Brassica↗
PubMed2006

A comparative study on the anatomy and development of different shapes of domatia in Cinnamomum camphora (Lauraceae).

BACKGROUND AND AIMS: Domatia are small organs usually found in the axils of major veins on the underside of leaves and, although they have received wide attention from ecologists, few detailed reports exist on their anatomy or development. This study is focused on the domatia of Cinnamomum camphora (Lauraceae) and is the first comparative study on the anatomy and development of the different shapes of domatia within a single plant. METHODS: Four types of domatia in C. camphora leaves were observed on paraffin sections under a microscope. KEY RESULTS: The domatia consisted of six histological parts: the upper epidermis, the upper mesophyll tissue, spongy tissue, the lower mesophyll tissue, the tissue filling the rim opening, and the lower epidermis. They differed from the non-domatial lamina mainly in the cell structure of the upper and lower mesophyll tissue and the rim tissue. Differences in domatium shapes were mainly associated with differences in the structure of the upper mesophyll and in the number and size of the rim tissue cells. Differences in the development of domatium types were observed in terms of initiation timing, differentiation of the upper mesophyll cells and degree of rim tissue development. CONCLUSIONS: In domatia, active anticlinal division in the lower mesophyll cells, as compared with the upper mesophyll cells, was coordinated with dynamic growth of rim tissue cells and resulted in cavity formation. The anatomical or developmental differences among the four types of domatia were related to the positions of the domatia within a leaf. In terms of the ecological implications, the major anatomical difference between the domatia used by herbivorous and carnivorous mites was in the development of the rim tissue.

Animals↗
PubMed1994

Premature microtubule-dependent cytoplasmic streaming in cappuccino and spire mutant oocytes.

Embryonic axis specification in Drosophila melanogaster is achieved through the asymmetric subcellular localization of morphogenetic molecules within the oocyte. The cappuccino and spire loci are required for both posterior and dorsoventral patterning. Time-lapse confocal microscopic analyses of living egg chambers demonstrated that these mutations induce microtubule reorganization and the premature initiation of microtubule-dependent ooplasmic streaming. As a result, microtubule organization is altered and bulk ooplasm rapidly streams during the developmental stages in which morphogens are normally localized. These changes in oocyte cytoarchitecture and dynamics appear to disrupt axial patterning of the embryo.

Animals↗
PubMed2006

Distinct short-range ovule signals attract or repel Arabidopsis thaliana pollen tubes in vitro.

BACKGROUND: Pollen tubes deliver sperm after navigating through flower tissues in response to attractive and repulsive cues. Genetic analyses in maize and Arabidopsis thaliana and cell ablation studies in Torenia fournieri have shown that the female gametophyte (the 7-celled haploid embryo sac within an ovule) and surrounding diploid tissues are essential for guiding pollen tubes to ovules. The variety and inaccessibility of these cells and tissues has made it challenging to characterize the sources of guidance signals and the dynamic responses they elicit in the pollen tubes. RESULTS: Here we developed an in vitro assay to study pollen tube guidance to excised A. thaliana ovules. Using this assay we discerned the temporal and spatial regulation and species-specificity of late stage guidance signals and characterized the dynamics of pollen tube responses. We established that unfertilized A. thaliana ovules emit diffusible, developmentally regulated, species-specific attractants, and demonstrated that ovules penetrated by pollen tubes rapidly release diffusible pollen tube repellents. CONCLUSION: These results demonstrate that in vitro pollen tube guidance to excised A. thaliana ovules efficiently recapitulates much of in vivo pollen tube behaviour during the final stages of pollen tube growth. This assay will aid in confirming the roles of candidate guidance molecules, exploring the phenotypes of A. thaliana pollen tube guidance mutants and characterizing interspecies pollination interactions.

Arabidopsis↗
PubMed1984

[Current status of the problem of malignant lymphoma (on the centenary of the theory of malignant lymphoma)].

Malignant lymphomas (ML) differ from other neoplasms by an extreme variety of the morphological terms used for designation of different variants of these tumours and different terms are used to describe the same neoplasm. This resulted in the simultaneous use in different countries of not less than 6 ML classifications including the WHO histocytological classification (1976), which is not universally accepted. Kiel's classification of non-Hodgkin's ML (1974) is the most popular in the majority of the West and East European countries, in USA there is a similar classification by Lukes and Collins (1975). The "Working formulation of ML for the use in clinics" (USA, 1982) starts to be used, although it is simply a terminological compromise also containing certain faults. The historical review of the evolution of the ML concept is given starting from Th. Billroth' works (1883); the concrete examples are given illustrating the dynamics of the ML terms and evaluation of their nature. The singularity of the developmental steps of this concept is noted, in particular the "reticulosis era" (1923-1973). The dependence of ML estimate upon the existing, in a given period, schemes of hemopoiesis is pointed out. The data on the state of this problem in different countries are presented and the necessity of its joint discussion by pathologists and clinicians in order to work out the identical nomenclature for the designation of the same type of ML is outlined.

Animals↗
PubMedDate not supplied

[Characteristics of esterase expression in interspecific hybrids of Drosophila of the group virilis].

A spectrum of esterase isozymes was studied in the larvae, adults and isolated seminiferous bulbs of hybrids D. virilis X D. littoralis. Different esterase isozymes were shown to be expressed codominantly in all cases studied. The differences found in the activity of paternal fractions at certain developmental stages were due to the preservation of species specific differences in the temporal dynamics of expression of some esterase isozymes.

Animals↗
PubMed1998

Laws for the dynamics of regulatory networks.

We start our analysis from historical but too seldom quoted papers by Delbrück, Noveck & Weiner, Cohn & Horibata and Monod & Jacob. We try to show how it became possible to draw a line coupling cell differentiation to the physical concept of multistationarity, and the latter to the concept of positive feedback circuits. Two laws give the minimal logical ingredients required for differentiative and homeostatic regulations. It is briefly shown how they can be used to treat such complex dynamics as deterministaic chaos, which, admittedly, does not yet belong to the corpus of developmental biology. It was taken as a challenge to express our ideas here in purely verbal terms, avoiding any formal treatment.

Animals↗
PubMed1990

A clinical practice model for treatment of college-aged incest survivors.

Adult incest survivors frequently exhibit signs and symptoms of posttraumatic stress disorder. Many clinicians have geared their group treatment of incest survivors to address these manifestations. Given the nature of the sexual abuse, the early developmental periods in which some trauma occurs, the past and current relationship between the victim and the perpetrator, and the dynamics inherent in this violation and betrayal of trust, love, and power within the family unit, additional clinical concerns and safeguards must be considered. In addition, the struggles of college-aged incest survivors to come to terms with their history of sexual abuse often mirror the developmental tasks faced by their peers--autonomy, intimacy, sexuality, and formation of personal values and ethics. To focus solely on the incest without also considering these developmental issues may solidify a gridlock between inadequate resolution of the developmental issues and the continued victimization of the student incest survivor. The author discusses a time-limited group treatment for college-aged incest survivors that uses a modified posttraumatic stress disorder model as a conceptual framework and addresses both sets of concerns.

Adolescent↗
PubMed2006

Cell differentiation and organ initiation at the shoot apical meristem.

Plants continuously generate organs at the flanks of their shoot apical meristems (SAMs). The patterns in which these organs are initiated, also called patterns of phyllotaxis, are highly stereotypic and characteristic for a particular species or developmental stage. This stable, predictable behaviour of the meristem has led to the idea that organ initiation must be based on simple and robust mechanisms. This conclusion is less evident, however, if we consider the very dynamic behaviour of the individual cells. How dynamic cellular events are coordinated and how they are linked to the regular patterns of organ initiation is a major issue in plant developmental biology.

Cell Differentiation↗
PubMed2000

Plastid tubules of higher plants are tissue-specific and developmentally regulated.

Green fluorescent stroma filled tubules (stromules) emanating from the plastid surface were observed in transgenic plants containing plastid-localized green fluorescent protein (GFP). These transgenic tobacco plants were further investigated by epifluorescence and confocal laser scanning microscopy (CSLM) to identify developmental and/or cell type specific differences in the abundance and appearance of stromules and of plastids. Stromules are rarely seen on chlorophyll-containing plastids in cell types such as trichomes, guard cells or mesophyll cells of leaves. In contrast, they are abundant in tissues that contain chlorophyll-free plastids, such as petal and root. The morphology of plastids in roots and petals is highly dynamic, and plastids are often elongated and irregular. The shapes, size, and position of plastids vary in particular developmental zones of the root. Furthermore, suspension cells of tobacco exhibit stromules on virtually every plastid with two major forms of appearance. The majority of cells show a novel striking 'octopus- or millipede-like' structure with plastid bodies clustered around the nucleus and with long thin stromules of up to at least 40 (micro)m length stretching into distant areas of the cell. The remaining cells have plastid bodies distributed throughout the cell with short stromules. Photobleaching experiments indicated that GFP can flow through stromules and that the technique can be used to distinguish interconnected plastids from independent plastids.

Cell Differentiation↗
PubMed2002

Developmentally regulated expression of type XV collagen correlates with abnormalities in Col15a1(-/-) mice.

Lack of type XV collagen in mice results in mild skeletal myopathy and increases vulnerability to exercise-induced skeletal muscle and cardiac injury [Proc. Natl. Acad. Sci. USA 98 (2001), 1194]. The expression of type XV collagen was studied during murine fetal development from 10.5 to 18.5 dpc using immunofluorescence. The first sign of type expression was seen in the capillaries of many tissues at 10.5 dpc, some of them showing developmental transitions in the expression. Interestingly, capillaries forming the blood-brain barrier and those of the sinusoidal type were essentially lacking in this collagen. Early expression was also detected in the skeletal muscle and peripheral nerves, while expression in the heart, kidney and lung appeared to be developmentally regulated. In addition, distinct staining was found in the perichondrium of the cartilage. Collectively, the dynamics of its expression during development, its localization in the basement membrane--fibrillar matrix interface and the consequences of its absence in mice suggest a structural role in providing stability at least in skeletal muscle and capillaries. The early prominent expression of type XV collagen in newly forming blood vessels could also indicate a possible role in angiogenic processes.

Animals↗
PubMed2004

The role of family systems in severe and recurrent psychiatric disorders: a developmental psychopathology view.

Family systems theory has been highly influential in the study of recurrent psychiatric disorders. This review examines two interrelated domains: research on expressed emotion (EE) attitudes among relatives (criticism, hostility, or emotionally overinvolvement) and relapses of schizophrenia or bipolar disorder, and randomized trials of family intervention in these populations. The literature is discussed in terms of contemporary systems theory and concepts from developmental psychopathology research. Several conclusions are drawn: (a) levels of EE are correlated with caregivers' attributions regarding the controllability of patients' behaviors; (b) EE attitudes are associated with bidirectional, mutually influential cycles of interaction between relatives and patients; and (c) family psychoeducational therapy, when combined with pharmacotherapy, is associated with lower rates of relapse in schizophrenia and bipolar illness. Underlying disturbances in family systems may emerge in response to illness symptoms in a family member, but also have recursive effects on the developmental course of the illness once manifest. The nature and stability of these recursive effects will depend on dynamic processes in the patient, the relative, and their relationship. Future research should elucidate mediating and moderating variables in the pathways from EE to patients' outcomes, and the conditions under which family treatments bring about favorable outcomes of psychiatric disorder.

Adult↗
PubMed2006

Intersection of signal transduction pathways and development.

One of the challenges of modern biology is to understand how cells within a developing organism generate, integrate, and respond to dynamic informational cues. Based on over two decades of intensive research, many parts and subroutines of the responsible signal transduction networks have been identified and functionally characterized. From this work, it has become evident that a complicated interplay between signaling pathways, involving extensive feedback regulation and multiple levels of cross-talk, underlies even the "simplest" developmental decision. Thus a signaling pathway can no longer be thought of as a rigid linear process, but rather must be considered a dynamic, self-interacting, and self-adjusting network. The Epidermal Growth Factor Receptor tyrosine kinase signaling pathway provides a prime vantage point from which to explore emerging principles in developmental signal transduction.

Animals↗
PubMed2002

Dynamics of intracellular calcium induced by lactate and glucose in rat pachytene spermatocytes and round spermatids.

Glycolytic metabolism in meiotic and post-meiotic spermatogenic cells shows differentiation-related changes. The developmental and physiological significance of these metabolic changes is not known. The aim of the present study was to test the hypothesis that glucose and lactate metabolism can modulate intracellular calcium [Ca2+](i) in spermatogenic cells in an opposing and dynamic manner. Fluorescent probes were used to measure [Ca2+](i) and pH(i), and HPLC was used to measure intracellular adenine nucleotides and mitochondrial sensing of ATP turnover. [Ca2+](i) in pachytene spermatocytes and round spermatids was modulated by changes in lactate and glucose concentrations in the media. The kinetics and magnitude of the [Ca2+](i) changes induced by lactate and glucose were different in meiotic and post-meiotic spermatogenic cells. The presence of glucose in the medium induced a decrease in pH(i) in spermatogenic cells. This glucose-induced pH(i) decrease occurred later than the changes in [Ca2+](i), which were also observed when the pH(i) decrease was inhibited, indicating that the glucose-induced [Ca2+](i) increase was not a consequence of pH(i) changes. Hexose phosphorylation in glycolysis was part of the mechanism by which glucose metabolism induced a [Ca2+](i) increase in spermatogenic cells. The sensitivity of [Ca2+](i) to carbohydrate metabolism was higher in round spermatids than in pachytene spermatocytes. Thus, differentiation-related changes in carbohydrate metabolism in spermatogenic cells determine a dynamic and differential modulation of their [Ca2+](i) by glucose and lactate, two substrates secreted by the Sertoli cells.

Adenosine Triphosphate↗
PubMed2006

Developmental methylation of the regulatory region of HoxB5 gene in mouse correlates with its tissue-specific expression.

We have studied the dynamics of de novo CpG methylation in the regulatory region of one of the homeobox gene HoxB5 during mouse development by sodium bisulfite sequencing. Methylation pattern was examined at embryonic day 18.5 and adult in kidney and spleen while in the liver the same exercise has been done in 11.5 dpc, 18.5 dpc, 5 dpp and in adult. In the liver at 11.5 dpc, all the 47 contiguous sites (including a CpG island from 2035 to 2330 bp) at 5' regulatory region of HoxB5 were unmethylated. Random methylation commences from 18.5 dpc and continues in 5 dpp and in the adult. In the kidney at 18.5 dpc, 26 CpGs were examined (excluding the CpG island region) and all of them were unmethylated but the fetal spleen had at least a few sites considerably methylated. In the adult there was a low level methylation in the kidney, on the other hand, in the spleen, all the CpGs were methylated except a few sites and certain sites were totally methylated. Thus in the adult, the level of methylation was much higher than in the fetal stage. On the other hand semi-quantitative RT-PCR revealed that the extent of expression of HoxB5 was higher in embryonic stages than in the adult. Thus HoxB5 is a good paradigm to support that the developmental methylation of HoxB5 and its expression pattern show an inverse correlation.

Animals↗