Agnathans recent and fossil,and the origin of jawed vertebrates

Summary During the last 15 years we have gained considerably more knowledge about the anatomy, physiology and molecular sequences of the modern agnathans. This knowledge has been analysed with modern systematic techniques which provide clear, unambiguous statements of relationships. At present there is a conflict between the results obtained using morphological/physiological data and that using molecular data. During the next few years it is likely that more molecular sequences will become available for analysis. Whether this will fuel the conflict or resolve the issue remains to be seen.The great increase in our knowledge of the diversity of fossil agnathans is continuing to provide much new anatomical information and this allows more firmly based phylogenies to be constructed. From these we may be able to delimit more precisely the course of evolutionary changes of functional systems in the early history of vertebrates.Many of our decisions concerning primitiveness or degeneracy of the modern agnathans can be gained through study of the ontogenetic development and the variation between the ontogenies from species to species. Lampreys are relatively well known in this respect. However, we lack comparable detailed studies of the development of hagfishes. A major research field is here waiting to be reaped.     

The Sensory Canal Systems of the Living Coelacanth, Latimeria Chalumnae: A New Instalment

Entire sensory canal systems of the coelacanth, Latimeria chalumnae, are described: not only the course of principal canals with their primary and secondary collaterals, but also the course and branches of the pit-line and reticular canals. The number of pores on the left side of the head were found to be 296 in an early (yolksac) embryo, 321 in a late term fetus, 485 in a juvenile, and 2974 in adults. This means that in latimeria most of the lateral-line canal system develop after parturition. Pit lines of the living coelacanth are not rows of superficial neuromasts but canals covered by a thin epidermis like in other sensory canals of the lateral line. These pit-line canals, however, have a very specific structure and branching pattern: the medial dorsal pit-line canal is connected by fine branches on top of the head. The infra-dentary pit-line canal connects via these branches with canals deep inside the bones. Several fine and richly branched canaliculi of unknown function radiate from each quadratojugal pit-line canal. The gular plate pit-line canal has superficially branching arms as well as connections to numerous deeper canals inside the bone. These canals consist of fine branches that in turn lead to and open on the ventral surface of the gular plates as small pores. The system is reminiscent of the reticular (pore) canal system known only from some fossil agnathans and fishes. Thus latimeria combines the reticular system of ancient vertebrates with the lateral-line system of modern fishes. The significance of this gular (possibly electro-sensory) system for feeding by the coelacanth will be discussed.     

Cell transformation by chemical agents--a review and analysis of the literature. A report of the U.S. Environmental Protection Agency Gene-Tox Program

The literature on cell transformation by chemical carcinogens has been critically reviewed. This subject is highly relevant to carcinogenesis in vivo, because the phenotypic changes that are collectively referred to as cell transformation usually involve the acquisition of tumorigenicity on inoculation into suitable rodent hosts. The systems chosen for review fall into 3 categories: cell strains (cells with a limited lifespan); cell lines (cells with an unlimited lifespan); and oncogenic viral-chemical interactions involving cells (Fischer rat embryo cells expressing an endogenous retrovirus, mouse embryo cells expressing the AKR leukemia virus, chemical enhancement of a simian adenovirus, SA7 transformation of Syrian hamster or rat embryo cells). Of the entire literature reviewed, 117 papers have been accepted for data abstraction by pre-defined criteria; these include 41 references to cell strains, 40 in cell lines, and 38 in viral-chemical interactions including cells. Because different systems have been reviewed, it would be meaningless to group all the compounds. The overall summary of the systems is as follows (many compounds have been tested in more than one system and, hence, are duplicated in these totals). (Chart: see text) In general, there is a reasonably good correlation between the results of the cell transformation systems and in vivo carcinogenesis. However, the many deficiencies of the EPA Merged Carcinogen List preclude definitive comparisons. Moreover, a number of 'false negatives' were obtained in systems that did not employ external metabolic activation. Further validation of all systems is required, but it seems very probable that several cell transformation systems will become valuable in assaying (with reasonable time and cost) the carcinogenic potential of environmental chemicals.     

An ancient mechanism of hindbrain patterning has been conserved in vertebrate evolution

The hindbrain is a vertebrate-specific embryonic structure of the central nervous system formed by iterative transitory units called rhombomeres (r). Rhombomeric cells are segregated by interhombomeric boundaries which are prefigured by sharp gene expression borders. The positioning of the first molecular boundary within the hindbrain (the prospective r4/r5 boundary) responds to the expression of an Iroquois (Irx) gene in the anterior (r4) and the gene vHnf1 at the posterior (r5). However, while Irx3 is expressed anteriorly in amniotes, a novel Irx gene, iro7, acts in teleosts. To assess the evolutionary history of the genes responsible for the positioning of the r4/r5 boundary in vertebrates, we have stepped outside the gnathostomes to investigate these genes in the agnathans Lethenteron japonicum and Petromyzon marinus. We identified one representative of the Hnf1 family in agnathans. Its expression pattern recapitulates that of vHnf1 and Hnf1 in higher vertebrates. Our phylogenetic analysis places this gene basal to gnathostome Hnf1 and vHnf1 genes. We propose that the duplication of an ancestral hnf1 gene present in the common ancestor of agnathans and gnathostomes gave rise to the two genes found in gnathostomes. We have also amplified 3 Irx genes in L. japonicum: LjIrxA, LjIrxC, LjIrxD. The expression pattern of LjIrxA (the agnathan Irx1/3 ortholog) resembles those of Irx3 or iro7 in gnathostomes. We propose that an Irx/hnf1 pair already present in early vertebrates positioned the r4/r5 boundary and that gene duplications occurred in these gene families after the divergence of the agnathans.     

无颌类脊椎动物适应性免疫系统的进化

适应性免疫系统的起源与进化问题一直是人们研究的热点, 以七鳃鳗为代表的无颌类脊椎动物, 被普遍认为处在进化出适应性免疫系统的边缘。因此, 研究无颌类脊椎动物适应性免疫的机制, 对揭示适应性免疫系统的起源与进化具有重要意义。研究表明, 无颌类在一定范围内具有高等脊椎动物特有的适应性免疫特征, 并发现了一些在结构或功能上与高等脊椎动物免疫相关基因同源的免疫因子。文章就近年来对无颌类脊椎动物适应性免疫系统机制的研究进展作一概述, 为进一步深入研究脊椎动物适应性免疫系统的起源与进化提供有益的参考。     

Olfactory memory: the long and short of it

It has been proposed that memory for odors does not have a short-term (or working) memory system. The distinction between short- and long- term memory in other sensory modalities has been generally supported by three main lines of evidence: capacity differences between the proposed systems, evidence of differential coding, and differential memory losses in neuropsychological patients. The present paper examines these issues in an effort to establish a similar distinction for the memory of olfactory stimuli. Each of these lines of evidence is examined in relation to the literature on olfactory memory. Based on this examination, it seems that there is at least preliminary support from each of these lines of evidence to advocate a distinction between a long- and short-term memory for olfactory stimuli. Emphasis is placed upon the qualitative similarity of olfactory memory to other memory systems. This similarity is further highlighted through an examination of the literature pertinent to serial position effects in memory for olfactory stimuli.      

The tricarboxylic acid cycle in Dictyostelium discoideum. I. Formulation of alternative kinetic representations.

Enzyme systems within living cells have recently been shown to be highly ordered structures that violate classic assumptions of the Michaelis-Menten formalism, which originally was developed for the characterization of isolated reactions in vitro. This evidence suggests that a thorough examination of alternative kinetic formalisms for integrated biochemical systems is in order. The purpose of this series of papers is to assess the utility of an alternative power-law formalism by carrying out a detailed comparative analysis of a relatively large, representative system--the tricarboxylic acid cycle of Dictyostelium discoideum. This system was chosen because considerable experimental information already has been synthesized into a detailed kinetic model of the intact system. In this first paper, we set the stage for subsequent analysis within the framework of the power-law formalism: we review the underlying theory, emphasizing recent developments, formulate the model in terms that are convenient for the analysis to follow, and develop the system representation in both the Michaelis-Menten and power-law forms. In the second paper (Shiraishi, F., and Savageau, M. A. (1992) J. Biol. Chem. 267, 22919-22925), these alternative representations are shown to be internally consistent and locally equivalent. The third paper (Shiraishi, F., and Savageau, M. A. (1992) J. Biol. Chem. 267, 22926-22933) provides a complete analysis of the steady state behavior and also treats the dynamic behavior of the model.     

Effect of low-level alpha-radiation on bioluminescent assay systems of various complexity.

This study addresses the effects of low-level alpha-radiation on bioluminescent assay systems of different levels of organization: in vivo and in vitro. Three bioluminescent assay systems are used: intact bacteria, lyophilized bacteria, and bioluminescent system of coupled enzyme reactions. Solutions of 241Am(NO3)3 are used as a source of alpha-radiation. It has been shown that activation processes predominate in all the three bioluminescent assay systems subjected to short-term exposure (20-55 h) and inhibition processes in the systems subjected to longer-term exposure to radiation. It has been found that these effects are caused by the radiation component of 241Am3+ impact. The intensity of the 241Am3+ effect on the bioluminescent assay systems has been shown to depend on the 241Am3+ concentration, level of organization and integrity of the bioluminescent assay system. The bioluminescent assay systems in vivo have been found to be highly sensitive to 241Am3+ (up to 10(-17) M).     

Bimolecular systems: I. Linear systems of complexes

A vast number of biologically important processes are based upon bimolecular systems. In these systems intermediate complexes are formed. Bimolecular systems in which no complex-complex interactions occur are called linear systems of complexes. A definition and some characteristic properties of these systems are given here. There may exist a contradiction of Onsager's principle of detailed balancing in these systems; however, no principal differences are found between the steady state behavior of an open system and that of a closed system. It is shown that the steady state behavior of a linear system of complexes of arbitrary complexity has some similarities with the steady state behavior of a simple bimolecular system, e.g., Michaelis-Menten enzymatic reaction. Multiplicity of action of the substances participating in biomolecular processes may produce some qualitative differences in the steady state behavior of the system.     

Monoclonal antibody production in murine ascites. I. Clinical and pathologic features

BACKGROUND AND PURPOSE: Murine ascites production has been associated with appreciable morbidity and mortality, thus raising animal-welfare concerns. To address these concerns, the clinicopathologic changes associated with in vivo production of monoclonal antibodies in mice were characterized, and results were compared among cell lines. METHODS: Five hybridoma cell lines were grown in groups of 20 mice. Fourteen days prior to inoculation with 10(6) hybridoma cells, mice were primed with 0.5 ml of pristane given intraperitoneally; 12 mice were sham treated (controls). Ascites fluid was collected a maximum of three times by abdominal paracentesis. Clinical observations and pre- and postabdominal tap body weights were recorded. Necropsies were performed on all mice. RESULTS: For all groups combined, overall survival to tap 1 was 98%, to tap 2 was 96%, and to tap 3 was 79%; survival among groups ranged from 90 to 100% for tap 1, 85 to 100% for tap 2, and 35 to 100% for tap 3. Disseminated intra-abdominal seeding with irregular soft tissue and/or solid tumor masses was observed at necropsy. CONCLUSIONS: Significant clinicopathologic changes were associated with monoclonal antibody production in mice, and differences between various hybridoma cell lines were apparent.     

A comparison of variant theories of intact biochemical systems. I. Enzyme-enzyme interactions and biochemical systems theory

The need for a well-structured theory of intact biochemical systems becomes increasingly evident as one attempts to integrate the vast knowledge of individual molecular constituents, which has been expanding for several decades. In recent years, several apparently different approaches to the development of such a theory have been proposed. Unfortunately, the resulting theories have not been distinguished from each other, and this has led to considerable confusion with numerous duplications and rediscoveries. Detailed comparisons and critical tests of alternative theories are badly needed to reverse these unfortunate developments. In this paper we (1) characterize a specific system involving enzyme-enzyme interactions for reference in comparing alternative theories, and (2) analyze the reference system by applying the explicit S-system variant within biochemical systems theory (BST), which represents a fundamental framework based upon the power-law formalism and includes several variants. The results provide the first complete and rigorous numerical analysis within the power-law formalism of a specific biochemical system and further evidence for the accuracy of the explicit S-system variant within BST. This theory is shown to represent enzyme-enzyme interactions in a systematically structured fashion that facilitates analysis of complex biochemical systems in which these interactions play a prominent role. This representation also captures the essential character of the underlying nonlinear processes over a wide range of variation (on average 20-fold) in the independent variables of the system. In the companion paper in this issue the same reference system is analyzed by other variants within BST as well as by two additional theories within the same power-law formalism--flux-oriented and metabolic control theories. The results show how all these theories are related to one another.     

The glutathione system. I. Synthesis, transport, glutathione transferases, glutathione peroxidases

During the last 10–15 years significant progress has been achieved in all directions of studies of the glutathione system. A series of new enzymes involved into metabolism of glutathione has been discovered. Many of these enzymes are polyfunctional and their new activities have been recognized. The enzymes interact with hormones and signal transduction systems. Significant progress has been achieved in the studies of intracellular, intercellular and inter-organ transport. The important achievement is employment of not only selective compounds-analyzers but also gene engineering methods for identification of new functions.     

Quantitative Genetics of Postponed Aging in Drosophila Melanogaster. I. Analysis of Outbred Populations

Selection has been used to create replicated outbred stocks of Drosophila melanogaster with increased longevity, increased later fecundity, and increased levels of physiological performance at later ages. The present study analyzed the quantitative transmission patterns of such stocks, employing extensive replication in numbers of stocks, individuals, and assayed characters. The populations used derived from five lines with postponed aging and five control lines, all created in 1980 from the same founding base population. The following characters were studied: early 24-hr fecundity, early ovary weight, early female starvation resistance, early male starvation resistance, female longevity and male longevity. Numerous crosses were performed to test for non-Mendelian inheritance, average dominance, maternal effects, sex-linkage and between-line heterogeneity. There was only slight evidence for any of these phenomena arising reproducibly in the characters studied. These findings suggest the value of this set of stocks for studies of the physiological basis of postponed aging.     

Studies on immobilized Saccharomyces cerevisiae. I. Analysis of continuous rapid ethanol fermentation in immobilized cell reactor

Rapid fermentation of cane molasses into ethanol has been studied in batch, continuous (free-cell and cell-immobilized systems) by a strain of Saccharomyces cerevisiae at temperature 30 degrees C and pH 5.0. The maximum productivity of ethanol obtained in immobilized system was 28.6 g L(-1) h(-1). The cells were immobilized by natural mode on a carrier of natural origin and retention of 0.132 g cells/g carrier was achieved. The immobilized-cell column was operated continuously at steady state over a period of 35 days. Based on the parameter data monitored from the system, mathematical analysis has been made and rate equations proposed, and the values of specific productivity of ethanol and specific growth rate for immobilized cells computed. It has been established that immobilized cells exhibit higher specific rate of ethanol formation compared to free cells but the specific growth rate appears to be comparatively low. The yield of ethanol in the immobilized-cell system is also higher than in the free-cell system.     

Genetic diversity analysis of maize lines using AFLP and TE-based molecular marker systems

Maize has been domesticated in diverse environments ranging from low latitudes in tropical countries to high latitudes in Canada. Because maize breeding programs primarily focus on hybrid vigor by selectively crossing inbred lines to maximize recombination, we collected a diverse array of commercial hybrid and inbred lines from southern Asia, China, and Canada and analyzed them by amplified length fragment polymorphism (AFLP), sequence-specific amplified polymorphism (SSAP), and CACTA-transposon display (TD) analyses. Cluster analyses using these molecular marker systems clearly differentiated these maize lines into three groups: southern Asian lines, northern Asian lines, and Canadian lines. However, principal coordinate analysis (PCoA) based on Nei’s distances grouped them into two groups: Asian and Canadian lines. Thus, groupings by cluster dendrograms and PCoA showed that geographic origin was a more dominant factor than growing seasonal differences resulting from different latitudes. The overall genetic diversity (Ht) was found to be high (more than 80 % molecular variations) among the maize lines by all three of the marker systems.     

Conductance studies on the interaction of lactose with alkali-metal halides in water and in formamide

The interaction of lactose with alkali-metal halides in solution in water and in formamide has been studied by employing conductance measurements. Conductance data of sodium and potassium halides in water and in formamide saturated with lactose at 50.0 ±0.05° are reported at several temperatures within a range of 25 to 70°. Plots of —log- K against 1/T showed a break at the saturation temperature, where two straight lines intersect one another. Divergence of the pairs of straight lines in these ternary, homogeneous systems has been found to be highly influenced by the structural properties of the solutes. The transitional behavior in the conductance values is explained for the system in terms of solute-solvent interactions involved in the electrolyte-solvent-nonelectrolyte systems.     

Structural Organization of the Blood-sinus Systems in Lampreys and Hagfish: Functional and Evolutionary Interpretations

Abstract The head and branchial regions of larval and adult lampreys and hagfish were studied histologically in serial sections. The most remarkable feature in these extant agnathans was the occurrence of large blood-sinuses. In larval lampreys, blood-sinuses are well developed in the velum, an organ that functions to introduce water and accompanying food particles from the mouth into the gill and alimentary regions. The sinuses in the velum may act to transduce the force of contraction of velar muscles to the stroke-like movement of the velum; without these sinuses muscular contractions might simply cause the velum to collapse. In adult lampreys, blood-sinuses are well developed in the peribranchial space that surrounds the branchial (gill) sac and is surrounded by the branchial pouch. It is possible that the force of contractions of the branchial-pouch muscles is transduced effectively to the branchial sac via the peribranchial blood-sinus and facilitates the expiration of water through the external gill pores. If the peribranchial sinus were absent, the muscular contraction might deform the branchial sac in an inappropriate manner. In the hagfish, the blood-sinus system is also well developed in the velum and peribranchial space, although the peribranchial sinus lies outside the muscular branchial pouch. In agnathans, the blood-sinus system may function, at least in part, as a kind of hydrostatic skeleton that transduces the force generated by muscular contraction.     

Applications of immortalized cells in basic and clinical neurology

Immortalized cell lines can serve as model systems for studies of neuronal development and restoration of function in models of neurological disease. Cell lines which result from spontaneous or experimentally-induced tumors have been used for these purposes. More recently, the techniques of genetic engineering have resulted in the production of cell lines with specific desired characteristics. This has been accomplished by insertion of a desired gene into a pre-existing immortal cell or by immortalizing primary cells. The production of immortal cell lines using temperature-sensitive immortalizing genes offers an additional method of controlling gene expression, and thereby controlling cell proliferation and differentiation. In the nervous system, these techniques have produced immortal cell lines with neuronal and glial properties.     

Gypsy moth cell lines divergent in viral susceptibility. I. Culture and identification.

A series of cell lines unique in insect virus susceptibility pattern have been isolated from the ovaries of the gypsy moth (Lymantria dispar: Lepidoptera: Lymantriidae) on a synthetic medium with mammalian and avian serum supplementation. Growth curves showed the poorest growth occurring on peptone-based media with somewhat better growth on amino-acid-based media. The best growth was obtained with combined media. Serological study distinguished the present cell lines from one another and from cell lines derived from other insect species grown routinely in the same laboratory. Baculovirus susceptibility among the new lines varied from no response to a specific complete replication response upon challenge by the homologous (gypsy moth) nuclear polyhedrosis virus.     

The two-wavelength method of microspectrophotometry. I. A microspectrophotometer and tests on model systems

In spite of a number of examples of the apparently successful application of the two-wavelength method of microspectrophotometry to biological materials, a demonstration of the effective transition from the theoretical to the practical aspects of the method has never been given. The following tests were carried out on model systems in order to confirm the practical validity of the method: (1) Spherical droplets of Sudan blue or Sudan IV (varying in volume by as much as 400 times) were measured with the surrounding blank field included and were found to have amounts of chromophore which conformed to the estimated droplet volume to within 3 to 6 per cent. (2) Repeated determinations on the same isolated nucleus gave results which did not vary in spite of wide variations in the area of the photometric field. (3) The results of repeated determinations on the same droplet of dye were unaffected by gross changes in the focus of the objective. The microspectrophotometer on which these measurements were made has been briefly described; it was designed specifically for the two-wavelength method. Some of the details of instrumentation have been discussed, in particular, the effects of non-uniform illumination and the contrasting demands of the two integral parts of this type of photometry. Although it has certain limitations, the two-wavelength method conforms to its theoretical promise and is a practical method of measuring light absorption in complex objects.