Biochemical divergence between cavernicolous and marine Sphaeromidae and the Mediterranean salinity crisis

Summary Allozymic variation in proteins encoded by 14 loci was analyzed in 3 cavernicolousMonolistra and in 2 marineSphaeroma species. Genetic distance data, high levels of heterozygosity and the divergence time calculations support the hypothesis thatMonolistra diverged from its Sphaeroma-like marine ancestor during the Messinian, in connection with the Mediterranean salinity critis.This research was supported by the National Research Council, Italy, grant No. 77.01490.04, and by funds of the Faculty of Sciences, University of Rome.     

Germline development in vertebrates and invertebrates

In all animals information is passed from parent to offspring via the germline, which segregates from the soma early in development and undergoes a complex developmental program to give rise to the adult gametes. Many aspects of germline development have been conserved throughout the animal kingdom. Here we review the unique properties of germ cells, the initial determination of germ cell fates, the maintenance of germ cell identity, the migration of germ cells to the somatic gonadal primordia and the proliferation of germ cells during development in vertebrates and invertebrates. Similarities in germline development in such diverse organisms as Drosophila melanogaster, Caenorhabditis elegans, Xenopus laevis and Mus musculus will be highlighted. Received 11 December 1998; received after revision 25 January 1999; accepted 25 January 1999     

Chemical communication in invertebrates

Conclusions In conclusion, olfactory pheromones are widespread in nature and control many fundamental aspects of an insect's life. Detailed behavioral observations in the field and laboratory indicate the great complexity of most pheromone communication systems. The preliminary electrophysiological experiments on single olfactory receptor neurons that we have described here, point toward the possibility of unraveling the basic physiological mechanisms underlying these behavioral complexities. This information is directly applicable to many problem areas in chemoreception and could provide a base for the rational use of pheromones in the control of insect pests. *** DIRECT SUPPORT *** A2025171 00003     

Melatonin: presence and formation in invertebrates

In vertebrates, it is now clearly demonstrated that the pineal gland is implicated in conveying photoperiodic information via the daily pattern of melatonin secretion. Invertebrates, like vertebrates, use photoperiodic changes as a temporal cue to initiate physiological processes such as reproduction or diapause. How this information is integrated in invertebrates remains an unsolved question. Our review will be an attempt to evaluate the possible role of melatonin in conveying photoperiodic information in invertebrates. It is now well demonstrated in both vertebrates and invertebrates that melatonin as well as its precursors or synthesizing enzymes are present in various organs implicated in photoreceptive processes or in circadian pacemaking. Melatonin, serotonin or N-acetyltransferase have been found in the head, the eyes, the optic lobe and the brain of various invertebrate species. In some species it has also been shown that melatonin is produced rhythmically with high concentrations reached during the dark period. Moreover, the physiological effects of melatonin on various periodic processes such as rhythmic contractions in coelenterates, fissioning of asexual planarians or reproductive events in flies have been reported in the literature. All these results support the hypothesis (refs 36, 37) that melatonin is not solely a pineal hormone but that it may be an evolutionary conservative molecule principally involved in the transduction of photoperiodic information in all living organisms.     

Formation of cardiovascular tubes in invertebrates and vertebrates

The cardiovascular system developed early in evolution and is pivotal for the transport of oxygen, nutrients, and waste products within the organism. It is composed of hollow tubular structures and has a high level of complexity in vertebrates. This complexity is, at least in part, due to the endothelial cell lining of vertebrate blood vessels. However, vascular lumen formation by endothelial cells is still controversially discussed. For example, it has been suggested that the lumen mainly forms via coalescence of large intracellular vacuoles generated by pinocytosis. Alternatively, it was proposed that the vascular lumen initiates extracellularly between adjacent apical endothelial cell surfaces. Here we discuss invertebrate and vertebrate cardiovascular lumen formation and highlight the possible modes of blood vessel formation. Finally, we point to the importance of a better understanding of vascular lumen formation for treating human pathologies, including cancer and coronary heart disease.     

Peptides related to vasopressin in invertebrates

Summary Compounds chemically related to the vertebrate neurohypophysial peptides, vasopressin and neurophysin, have been detected in recent years in the brain and in ganglia of invertebrates. Most data acquired so far have been obtained in insects and in molluscs. Evidence suggesting that these compounds might exert neurohormonal and neurotransmitter functions in these species is reviewed.Work by the authors is supported in part by Swiss NSF grant 3.560.083.     

Hemolysins: Pore-forming proteins in invertebrates

Summary Invertebrates possess lytic molecules which lyse vertebrate erythrocytes. In all the species studied so far, hemolytic activity depends on proteins which possess a wide range of reactivity. It is generally calcium-dependent and heat-labile, although calcium-independent and heat-stable hemolysins have also been detected. The molecules interact with sugars or lipids which could represent the membrane receptors by which circular lesions on target membranes are produced.On the basis of some analogies with vertebrate lytic molecules it is conceivable that the hemolysins evolved from a common ancestral gene which also led to vertebrate pore-forming proteins.     

Hemolysins: pore-forming proteins in invertebrates

Invertebrates possess lytic molecules which lyse vertebrate erythrocytes. In all the species studied so far, hemolytic activity depends on proteins which possess a wide range of reactivity. It is generally calcium-dependent and heat-labile, although calcium-independent and heat-stable hemolysins have also been detected. The molecules interact with sugars or lipids which could represent the membrane receptors by which circular lesions on target membranes are produced. On the basis of some analogies with vertebrate lytic molecules it is conceivable that the hemolysins evolved from a common ancestral gene which also led to vertebrate pore-forming proteins.     

On the existence of cytokines in invertebrates

Based on the assumption that invertebrates, like vertebrates, possess factors regulating responses to infection or wounding, studies dealing with the evolution of immunity have focussed on the isolation and characterisation of putative cytokine-related molecules from invertebrates. Until recently, most of our knowledge of cytokine- and cytokine receptor-like molecules in invertebrates relies on functional assays and similarities at the physicochemical level. As such, a phylogenetic relationship between invertebrate cytokine-like molecules and vertebrate counterparts could not be convincingly demonstrated. Recent genomic sequence analyses of interleukin-1-receptor-related molecules, that is Toll-like receptors, and members of the transforming growth factor-β superfamily suggest that the innate immune system of invertebrates and vertebrates evolved independently. In addition, data from protochordates and annelids suggest that invertebrate cytokine-like molecules and vertebrate factors do not have the same evolutionary origin. We propose instead that the convergence of function of invertebrate cytokine-like molecules and vertebrate counterparts involved in innate immune defences may be based on similar lectin-like activities. Received 27 November 2000; received after revision 11 December 2000; accepted 13 December 2000     

Differential display analysis of gene expression in invertebrates

Screening for differentially expressed genes is a straightforward approach to study the molecular basis for changes in gene expression. Differential display analysis has been used by investigators in diverse fields of research since it was developed. Differential display has also been the approach of choice to investigate changes in gene expression in response to various biological challenges in invertebrates. We review the application of differential display analysis of gene expression in invertebrates, and provide a specific example using this technique for novel gene discovery in the nematode Caenorhabditis elegans.     

Chemical studies of marine invertebrates. XXVII. On the absolute configuration of aromadendrane sesquiterpenes from the soft coral Cespitularia aff. subviridis

Summary Allo-aromadendrene, (-) viridiflorol and (+) ledol have been identified as minor constituents of the soft coral Cespitularia aff. subviridis.For part XXVI, see Y. M. Sheikh, C. Djerassi, J. C. Braekman, D. Daloze, M. Kaisin, B. Tursch an R. Karlsson, Tetrahedron (in press).Acknowledgments. This work was supported by NATO Research Grant ES-003. We thank Dr J. Verseveldt for the identification of the animal.Chercheur Qualifité du Fonds National de la Recherche Scientifique Belge.Service de Chimie Organique E. P.     

The content of citrate in resting muscles from vertebrates and invertebrates

Summary There is a marked difference between the content of citrate of anaerobic and aerobic muscles. The variation of the citrate content in insect flight muscles is very small.     

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.