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At least 1,261 records · Page 70Linked to original sources
PubMed1993

Structures and molecules involved in generation and regulation of biological rhythms in vertebrates and invertebrates.

Melatonin from the retina and the pineal gland functions in neuroendocrine hierarchies. Photoreceptors--eyes and extraretinal--detect light. Oscillators--pineal and suprachiasmatic nuclei--act as pacemakers. Driven neuroendocrine rhythms carry temporal hormone signals throughout the body. Light controls melatonin: light sets the phase of the melatonin rhythm and determines the duration of melatonin synthesis. By these means, circadian rhythms (e.g., in locomotor activity and body temperature) and seasonal rhythms (e.g., in reproduction) are controlled.

Animals↗
PubMed1988

Optical monitoring of activity of many neurons in invertebrate ganglia during behaviors.

Optical methods for monitoring neuron activity were developed because these methods lend themselves to simultaneous multiple-site measurements. With the use of new voltage-sensitive dyes, the dye-related pharmacology and photodynamic damage appear to be relatively unimportant. Using multiple-site measurements made with a 124-element photodiode array, we estimated that approximately 30 of the 200 neurons present in the Navanax buccal ganglion make action potentials during feeding and that approximately 300 of the 1100 neurons present in the Aplysia abdominal ganglion are active during the gill-withdrawal reflex. The fact that a light mechanical touch to the siphon skin activated such a large number of neurons in the abdominal ganglion suggests that understanding the neuronal basis of the gill-withdrawal reflex and its behavioral plasticity may be forbiddingly difficult.

Animals↗
PubMed1991

Replacement of vertebrate serum with lipids and other factors in the culture of invertebrate cells, tissues, parasites, and pathogens.

Culture medium supplementation with vertebrate serum results in the selection of fibroblastoid insect cell lines and a general decline during continuous subculturing of both morphologic and functional differentiation of the surviving cells. Essential lipid mixtures can substitute for vertebrate serum in the culture of insect and some vertebrate cells, tissues, parasites, and pathogens. The provision of sterols and essential (with nonessential) polyunsaturated fatty acids as phospholipids in oxidation-protected peptoliposomes or proteoliposomes allows cells in culture to duplicate in vivo specific membranes more accurately. Such lipid-corrected membranes allow cultured cells to communicate with neighboring cells through the extracellular matrix, effectively transmit hormonal signals directly and via receptor control, and respond with various tissue-specific functions and differentiation states as directed.

Animals↗
PubMed1991

Growth factors in invertebrate in vitro culture.

An increasing number of polypeptide growth factors have been identified that have proven essential in the development of defined cell culture media for mammalian cell culture. The development of defined mammalian cell culture media, in turn, has provided an environment for studying cell lines in an experimentally manageable unit for studying the action of cellular regulators and genes that determine the properties of cells. Evidence that vertebrate growth factors may be present in insects is based on DNA sequences that encode epidermal growth factor and transforming growth factor-beta. However, research on the influence of commercially available vertebrate growth factors is very limited. Although the majority of insect growth-promoting substances studied were isolated directly from insect hemolymph, few of these have been purified to the extent that they could be tested in insect cell, tissue, and endoparasite cultures. Research is needed in both of these areas to aid in developing defined insect culture systems, and to understand better the regulation of postembryonic growth and development in insects.

Animals↗
PubMed1993

FRAR course on laboratory approaches to aging. Genetic influences on aging in mammals and invertebrates.

A central theme underlies this review: "Genetics offers an important tool for identifying key molecular events that are involved in specifying biological functions." This approach has been used repeatedly to understand such diverse biological phenomena as oncogenesis, development, and the cell cycle, but has only recently been applied to the analysis of organismic aging and senescence. The power of the genetic approach lies in the ability to integrate phenomena that are displayed at multiple observational levels (i.e., from the molecular to the whole organism), and the power to reveal causal factors that are not dependent upon the prejudice of the investigator. I discuss several areas where genetics has been fruitfully applied to the study of the aging processes: human genes identified by "segmental progeroid" mutations; neurological diseases of the elderly; the limited proliferative life span of human somatic cells in tissue culture; studies on the life span of the mouse; and genetic analysis of life span in shorter-lived metazoans (Drosophila melanogaster and Caenorhabditis elegans), and the yeast Saccharomyces cerevisiae.

Aging↗
PubMed1999

Introduction: invertebrate axons find their way.

The mechanisms that generate the immense complexity of synaptic connections within the developing nervous system have fascinated biologists for decades. Analysis of nervous system development in simple systems, such as insects, has made a major contribution to our understanding of the cellular and molecular mechanisms that control the formation of axon pathways and precise connections. This enterprise has a long, interesting, and somewhat controversial history. This collection of reviews on axon guidance in insects provides a brief update to integrate current molecular and developmental insights in a number of areas from initial axon pathfinding to the recognition of synaptic partners.

Animals↗