空间信息技术与深远海渔业资源开发

深远海渔业资源作为人类食用的优质蛋白来源,其开发受到各渔业国家的重视。以卫星遥感、地理信息系统等为代表的空间信息技术已经在海洋渔业中得到较为广泛的应用,主要包括卫星遥感渔场环境监测及渔情分析预报、鱼类洄游路径的监测、渔船作业位置的分布与监测等。针对深远海渔业资源的捕捞开发,重点综述了空间信息技术在深远海渔业资源开发中应用的现状以及应用前景分析。     

From nucleosome to chromosome: a dynamic organization of genetic information

Gene activity is controlled at different levels of chromatin organization, which involve genomic sequences, nucleosome structure, chromatin folding and chromosome arrangement. These levels are interconnected and influence each other. At the basic level nucleosomes generally occlude the DNA sequence from interacting with DNA-binding proteins. Evidently, nucleosome positioning is a major factor in gene control and chromatin organization. Understanding the biological rules that govern the deposition and removal of the nucleosomes to and from the chromatin fiber is the key to understanding gene regulation and chromatin organization. In this review we describe and discuss the relationship between the different levels of chromatin organization in plants and animals.     

The role of neuromediators and proteins in genetic and functional organization of animal brain

It was shown that animals that differ in behavioral characteristics (August and Wistar rats) also differ in neurotransmitter and protein metabolism, which can be considered as tests that adequately reflect the functional condition of the central nervous system. These differences are expressed at the level of both subcortical structures (hippocampus and caudate nucleus) and various morphofunctional types of the sensorimotor cortex neurons (layers III and V). Studies on genetically different animals strains have revealed metabolic features that allow determination of individual behavioral features and estimation of individual brain structures in these processes.     

Spatial genome organization

The linear sequence of genomes exists within the three-dimensional space of the cell nucleus. The spatial arrangement of genes and chromosomes within the interphase nucleus is nonrandom and gives rise to specific patterns. While recent work has begun to describe some of the positioning patterns of chromosomes and gene loci, the structural constraints that are responsible for nonrandom positioning and the relevance of spatial genome organization for genome expression are unclear. Here we discuss potential functional consequences of spatial genome organization and we speculate on the possible molecular mechanisms of how genomes are organized within the space of the mammalian cell nucleus.     

Spatial organization in bacterial chemotaxis

Spatial organization of signalling is not an exclusive property of eukaryotic cells. Despite the fact that bacterial signalling pathways are generally simpler than those in eukaryotes, there are several well‐documented examples of higher‐order intracellular signalling structures in bacteria. One of the most prominent and best‐characterized structures is formed by proteins that control bacterial chemotaxis. Signals in chemotaxis are processed by ordered arrays, or clusters, of receptors and associated proteins, which amplify and integrate chemotactic stimuli in a highly cooperative manner. Receptor clusters further serve to scaffold protein interactions, enhancing the efficiency and specificity of the pathway reactions and preventing the formation of signalling gradients through the cell body. Moreover, clustering can also ensure spatial separation of multiple chemotaxis systems in one bacterium. Assembly of receptor clusters appears to be a stochastic process, but bacteria evolved mechanisms to ensure optimal cluster distribution along the cell body for partitioning to daughter cells at division.     

Spatial and temporal organization in retinal units

Zusammenfassung Mittels Mikroelektroden wurde von den Ganglienzellen der Netzhaut decerebrierter bzw. pretigeminaler Katzen die Erregung registriert, die man bei zeitlich konstantem oder sinusförmig moduliertem Licht im stationären Zustand erhält. Eine Analyse der Spikeintervall-Verteilung zeigt, daß die Verteilungsfunktion invariant gegenüber den Reizbedingungen ist, wenn man sie über dem Zeitmaßstab der registrierten Zelle aufträgt. Die Analyse des Korrelationskoeffizienten zwischen den Erregungen verschiedener Einheiten der Netzhaut, die mit ein und derselben Mikroelektrode registriert wurden, führt zu dem Ergebnis, daß zwischen diesen Einheiten weder im Dunkeln noch unter Lichteinwirkung eine statistische Abhängigkeit besteht.

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This research was supported by the Office of Scientific Research, EOAR, through the European Office, Aerospace Research, United States Air Force, under Contract AF 61 (052)-830 and by Impresa di Cibernetica del C.M.R.     

Insights into the urbilaterian brain: conserved genetic patterning mechanisms in insect and vertebrate brain development

Recent molecular genetic analyses of Drosophila melanogaster and mouse central nervous system (CNS) development revealed strikingly similar genetic patterning mechanisms in the formation of the insect and vertebrate brain. Thus, in both insects and vertebrates, the correct regionalization and neuronal identity of the anterior brain anlage is controlled by the cephalic gap genes otd/Otx and ems/Emx, whereas members of the Hox genes are involved in patterning of the posterior brain. A third intermediate domain on the anteroposterior axis of the vertebrate and insect brain is characterized by the expression of the Pax2/5/8 orthologues, suggesting that the tripartite ground plans of the protostome and deuterostome brains share a common evolutionary origin. Furthermore, cross-phylum rescue experiments demonstrate that insect and mammalian members of the otd/Otx and ems/Emx gene families can functionally replace each other in embryonic brain patterning. Homologous genes involved in dorsoventral regionalization of the CNS in vertebrates and insects show remarkably similar patterning and orientation with respect to the neurogenic region (ventral in insects and dorsal in vertebrates). This supports the notion that a dorsoventral body axis inversion occurred after the separation of protostome and deuterostome lineages in evolution. Taken together, these findings demonstrate conserved genetic patterning mechanisms in insect and vertebrate brain development and suggest a monophyletic origin of the brain in protostome and deuterostome bilaterians.     

Spatial organization of axonal microtubules

Several workers have found that axonal microtubules have a uniform polarity orientation. It is the "+" end of the polymer that is distal to the cell body. The experiments reported here investigate whether this high degree of organization can be accounted for on the basis of structures or mechanisms within the axon. Substantial depolymerization of axonal microtubules was observed in isolated, postganglionic sympathetic nerve fibers of the cat subjected to cold treatment; generally less than 10% of the original number of microtubules/micron 2 remained in cross section. The number of cold stable MTs that remained was not correlated with axonal area and they were also found within Schwann cells. Microtubules were allowed to repolymerize and the polarity orientation of the reassembled microtubules was determined. In fibers from four cats, a majority of reassembled microtubules returned with the original polarity orientation. However, in no case was the polarity orientation as uniform as the original organization. The degree to which the original orientation returned in a fiber was correlated with the number of cold-stable microtubules in the fiber. We suggest that stable microtubule fragments serve as nucleating elements for microtubule assembly and play a role in the spatial organization of neuronal microtubules. The extremely rapid reassembly of microtubules that we observed, returning to near control levels within the first 5 min, supports microtubule elongation from a nucleus. However, in three of four fibers examined this initial assembly was followed by an equally rapid, but transient decline in microtubule number to a value that was significantly different than the initial peak. This observation is difficult to interpret; however, a similar transient peak has been reported upon repolymerization of spindle microtubules after pressure induced depolymerization.     

Spatial organization of catalase proteins

The three-dimensional structure of the heme-containing fungal catalase fromPenicillium vitale (m.m. 2,80,000) has been studied by X-ray analysis at 2.0 A resolution. The molecule is tetramer, each subunit contains 670 aminoacid residues identified to construct “X-ray” primary structure. The subunit is built of three compact domains and their connections. The first domain of about 350 residues contains aβ-barrel flanked by helices, the second domain of 70 residues is formed by four helices and the third one is composed of 150 residues and is topologically similar to flavodoxin. The active site including heme is deeply buried near theβ-barrel. A comparison of the structure of catalase fromPenicillium vitale with that of beef liver catalase revealed very close structural homology of the first and the second domain, but the third domain is entirely absent in beef liver catalase. A catalase from thermophillic bacteriaThermus thermophilus (m.m. 2,10,000) has been first isolated, crystallized and studied by X-ray analysis. Crystals are cubic, space group is P2₁3, a = 133.4 Å. The molecule is a hexamer with trigonal symmetry 32. The electron density map at 3 Å resolution made it possible to trace the polypeptide chain. The main structural motif is formed by four near parallel helices. There is no heme inThermus thermophilus catalase, the active site is between the four helices and contains two manganese ions.