The Histophysiology of the Prolactin Cell in Non-Mammalian Vertebrates

With the exception of the agnathan fishes, a prolactin cellhas been identified in all vertebrates in which it has beensought. This review examines the structure of the prolactin-producingpituitary cell in non-mammalian vertebrates, the manner in whichit responds to natural and artificial stimuli, and its controlby neural and humoral factors. Fundamental similarities anddifferences are described in an attempt to understand betterits method of operation. Given our present state of knowledge, there is, among all theapparent diversity, a similarity in the basic structure andmorphological response of this cell in teleosts, amphibians,reptiles, and birds. One can identify and speak with relativecertainty about a specific adenohypophysial cell called a "prolactincell." More profound differences may be found at the level ofcontrol mechanisms, chemistry of the hormone(s), and the natureof receptivity and response of target tissues. It appears that although there are basic similarities in thedesign of the prolactin cell, the systems that control its activitiesmay differ and the similar products produced by the cell maybe used toward different ends.     

新药发现与开发的技术展望

生命科学的高速发展改变了新药研究开发的传统模式。以基因组学为主导的多领域、多学科和多专业的交叉融合极大地提高了发现先导化合物的速率。体外药代和毒性快速检测手段的出现将突破新药临床前评估的技术瓶颈,中药现代化的内涵会以国际通用科学语言进行诠释,预见一系列治疗严重危害人类健康和生命的疾病的创新药物,将在今后20年内成功上市,广泛应用。     

Functional Evolution of Prolactin and Growth Hormone in Lower Vertebrates

Some aspects of prolactin and growth hormone biology in fishesand amphibians are considered, including the nature of the secretorycells, the regulation of their activity, the chemistry of thehormones, and their physiological activity in relation to hydromineralmetabolism and to growth and development. Inasmuch as most ofthe information is derived from only a small number of teleostand amphibian species, a broad evolutionary biology is difficultto derive without information from other fish groups especially,and a survey must be confined largely to a comparative biologyof some representative higher bony fishes with some representativeanurans and urodeles.     

Evolutionary Correlations Between Early Development and Life History in Plethodontid Salamanders and Teleost Fishes

SYNOPSIS. This study compares the relationships among earlydevelopment and life history characters between two monophyleticgroups, salamanders and teleost fishes. Plethodontid salamandershave large eggs and slow development. Large egg size in plethodontidsalamanders has been shown to influence several aspects of earlydevelopment, including: (1) time of holoblastic cleavage, (2)thickness of the blastocoel roof, (3) gastrulation (morphogeneticprocesses and timing), (4) early developmental rate, (5) formationof an embryonic disk, and (6) percentage of egg volume contributingto embryonic structures. Egg size is just one of several factorsthat influence the rate of development. While the slow developmentof plethodontids may have evolutionary implications for timingof oviposition, the lack of a clear correlation between thesevariables indicates that other life history characters needto be studied. Comparisons of the timing of oviposition in 28plethodontid species reveal that oviposition in the fall orwinter is the derived condition. On the basis of six early developmentaland six life history characters examined, there do not appearto be strong relationships between these two character sets.Evolutionary increases in egg size that delay when the egg cleavesholoblastically in some amphibian lineages (such as plethodontids)have been considered to be analogous to the changes that ledto the evolution of meroblastic cleavage in such lineages asamniotes. However, teleosts provide an interesting contrastto this standard scenario: The evolution of meroblastic cleavageis not correlated with an increase in egg size, but rather,with a decrease in egg size. Changes in early development ofteleosts that led to the evolution of meroblastic cleavage mayhave significant relationships with life history traits becauseof osmotic influences and could qualify as a key innovation.     

Growth Hormone and Prolactin Action in a Teleost Anabas testudineus (Bloch): Effect of the Time of Administration

Circadian rhythms play a very important role on metabolic process and have considerable effects on growth, especially in ectotherms. Like variation in hormone levels, the sensitivity of target cells may show diurnal or seasonal fluctuations. The aim of this study was to compare the effects of morning versus evening injections of growth hormone and prolactin on malic enzyme, glucose-6-phosphate dehydrogenase, isocitrate dehydrogenase, aspartate aminotransferase, alanine aminotransferase and Na⁺,K⁺-ATPase in a teleost Anabas testudineus. Activities of malic enzyme, glucose-6-phosphate dehydrogenase and isocitrate dehydrogenase of the two control groups themselves differ significantly at morning and evening. Early morning administration of growth hormone increases malic enzyme, glucose-6-phosphate dehydrogenase and isocitrate dehydrogenase activities while evening administration of growth hormone does not effect these enzymes. Transaminase activities were stimulated by morning and evening administration of GH and PRL. Na⁺,K⁺-ATPase activity was stimulated by morning administration and inhibited by evening treatment of both hormones. The results reveal that a given hormone may provide a different message to the target tissues at different periods of the day.     

Transducin Duplicates in the Zebrafish Retina and Pineal Complex: Differential Specialisation after the Teleost Tetraploidisation

Gene duplications provide raw materials that can be selected for functional adaptations by evolutionary mechanisms. We describe here the results of 350 million years of evolution of three functionally related gene families: the alpha, beta and gamma subunits of transducins, the G protein involved in vision. Early vertebrate tetraploidisations resulted in separate transducin heterotrimers: gnat1/gnb1/gngt1 for rods, and gnat2/gnb3/gngt2 for cones. The teleost-specific tetraploidisation generated additional duplicates for gnb1, gnb3 and gngt2. We report here that the duplicates have undergone several types of subfunctionalisation or neofunctionalisation in the zebrafish. We have found that gnb1a and gnb1b are co-expressed at different levels in rods; gnb3a and gnb3b have undergone compartmentalisation restricting gnb3b to the dorsal and medial retina, however, gnb3a expression was detected only at very low levels in both larvae and adult retina; gngt2b expression is restricted to the dorsal and medial retina, whereas gngt2a is expressed ventrally. This dorsoventral distinction could be an adaptation to protect the lower part of the retina from intense light damage. The ontogenetic analysis shows earlier onset of expression in the pineal complex than in the retina, in accordance with its earlier maturation. Additionally, gnb1a but not gnb1b is expressed in the pineal complex, and gnb3b and gngt2b are transiently expressed in the pineal during ontogeny, thus showing partial temporal subfunctionalisation. These retina-pineal distinctions presumably reflect their distinct functional roles in vision and circadian rhythmicity. In summary, this study describes several functional differences between transducin gene duplicates resulting from the teleost-specific tetraploidisation.     

De novo Biosynthesis of Purines in the Retina: Evolutionary Aspects

The author's own experimental findings and some literature data are summarized concerning the presence in the retina of the key enzymes of de novo biosynthesis of purines, (adenine and guanine), ones of the first organic compounds that appeared on the Earth and are the main components of DNA and RNA, nucleic acids providing protein synthesis. For the first time, highly purified preparations of these enzymes from the nerve tissue have been obtained, and their properties, activity control, and distribution in the photoreceptor cells have been studied. The data obtained are compared with the literature data on these enzymes in liver and on the systems regulating the enzyme activity in E. coli. The light-dependent, genetically determined changes in the key enzyme activities were found in the retina within the 24-h period: these activities significantly differed in the daytime and night periods (biorhythms), which indicates a direct relation of the photoreceptor to the retinal adaptation system. The data on diversity of retinal photoreceptors and their presence in cells of other tissues, as well as possible perspectives of this direction of research are briefly discussed. In each section, the evolutionary aspects of the obtained facts are considered.     

Olfactory Receptor Multigene Family in Vertebrates: From the Viewpoint of Evolutionary Genomics

Olfaction is essential for the survival of animals. Diverse odor molecules in the environment are detected by the olfactory receptors (ORs) in the olfactory epithelium of the nasal cavity. There are ~400 and ~1,000 OR genes in the human and mouse genomes, respectively, forming the largest multigene family in mammals. The relationships between ORs and odorants are multiple-to-multiple, which allows for discriminating almost unlimited number of different odorants by a combination of ORs. However, the OR-ligand relationships are still largely unknown, and predicting the quality of odor from its molecular structure is unsuccessful.Extensive bioinformatic analyses using the whole genomes of various organisms revealed a great variation in number of OR genes among species, reflecting the diversity of their living environments. For example, higher primates equipped with a well-developed vision system and dolphins that are secondarily adapted to the aquatic life have considerably smaller numbers of OR genes than most of other mammals do. OR genes are characterized by extremely frequent gene duplications and losses. The OR gene repertories are also diverse among human individuals, explaining the diversity of odor perception such as the specific anosmia.OR genes are present in all vertebrates. The number of OR genes is smaller in teleost fishes than in mammals, while the diversity is higher in the former than the latter. Because the genome of amphioxus, the most basal chordate species, harbors vertebrate-like OR genes, the origin of OR genes can be traced back to the common ancestor of the phylum Chordata.     

Identifying and Characterizing a Novel Protein Kinase STK35L1 and Deciphering Its Orthologs and Close-Homologs in Vertebrates

Background

The human kinome containing 478 eukaryotic protein kinases has over 100 uncharacterized kinases with unknown substrates and biological functions. The Ser/Thr kinase 35 (STK35, Clik1) is a member of the NKF 4 (New Kinase Family 4 ) in the kinome with unknown substrates and biological functions. Various high throughput studies indicate that STK35 could be involved in various human diseases such as colorectal cancer and malaria.

Methodology/Principal Findings

In this study, we found that the previously published coding sequence of the STK35 gene is incomplete. The newly identified sequence of the STK35 gene codes for a protein of 534 amino acids with a N-terminal elongation of 133 amino acids. It has been designated as STK35L (STK35 long). Since it is the first of further homologous kinases we termed it as STK35L1. The STK35L1 protein (58 kDa on SDS-PAGE), but not STK35 (44 kDa), was found to be expressed in all human cells studied (endothelial cells, HeLa, and HEK cells) and was down-regulated after silencing with specific siRNA. EGFP-STK35L1 was localized in the nucleus and the nucleolus. By combining syntenic and gene structure pattern data and homology searches, two further STK35L1 homologs, STK35L2 (previously known as PDIK1L) and STK35L3, were found. All these protein kinase homologs were conserved throughout the vertebrates. The STK35L3 gene was specifically lost during placental mammalian evolution. Using comparative genomics, we have identified orthologous sets of these three protein kinases genes and their possible ancestor gene in two sea squirt genomes.

Conclusions/Significance

We found the full-length coding sequence of the STK35 gene and termed it as STK35L1. We identified a new third STK35-like gene, STK35L3, in vertebrates and a possible ancestor gene in sea squirt genome. This study will provide a comprehensive platform to explore the role of STK35L kinases in cell functions and human diseases.     

Intracellular Organization: Evolutionary Origins and Possible Consequences to Metabolic Rate Control in Vertebrates

We adopt the position that metabolism originated at (or near)mineral surfaces prior to the origin of the first cells. Basedon current views of the organization of contemporary animalcells we speculate that the metabolism of the immediate ancestorsof eukaryotic cells required these non-biological surfaces,but that the latter were subsequently replaced by membranes,and nuclear and cytoplasmic matrix proteins which, we argue,remain as required participants in the intermediary metabolismof contemporary eukaryotic cells. The idea that such an lntracellularorganization could have provided a fundamental means by whichto control metabolic rate at the level of the intact animalis considered next. In the case of vertebrates we suggest thatthe organismic level of control might operate throughthe rateof capillary blood flow, as proposed in the Flow Theory of Coulson(1986): by controlling the rate at which the organized enzymearrays within the cells are perfused with substrate, cellularmetabolic rates could be set throughout the organism in an integratedfashion. Although there are problems with this linkage the interestingpossibility arises that the metabolic rate of individual cellsmay be subservient to the organism, being driven not so muchby the well known intracellular controls of concentration-based-biochemistryas by the flow of nutrients through the cells.     

Melatonin: A Discussion of Its Evolution and Actions in Vertebrates

SYNOPSIS. Melatonin has many actions in vertebrates, with someconsidered hormonal. But are some melatonin actions more ancientthan others? A survey of the tissues which synthesizemelatonindemonstrates that some are more recent vertebrate characterscompared to others, indicating that melatonin action in thesetissues also is more recent. The lateral eyes and pineal organsappear to be very ancient sources of melatonin and any actionthis molecule has within these tissues should be consideredprimordial. We hypothesize that melatonin's first actions (functions)were paracrine, that is, operating within these photoreceptivestructures to facilitate the process of photoreception. Suchactions have been documented. It is hypothesized that melatoninsynthesis occurred at nightwithin the pineal organs and retinasof ancient vertebrates, as is the case among extant vertebrates.Accompanying the nightly synthesis of melatonin for paracrinefunction, secretion of melatonin either incidental or for detoxificationby the liver occurred, providing a faithful template of theonset and/or duration of the scotophase. This nightly pulseof melatonin could provide important timing information to distanttissues capable of receiving the signal. The number of physiologicalsystems within vertebrates "using" thenightly circulating melatoninpulse, and the apparent increased importance of circulatingmelatonin in timing physiological events in mammals, like reproduction,is the result of recent cooptation.     

Concept,Discovery and Development of MMI Linkage: Story of a Novel Linkage: for Antisense Constructs

Abstract

Methylene(methylimino) or MMI linkage is a novel backbone modification that has enormous potential in the oligonucleotide-based antisense therapeutics as a replacement for the natural phosphodiester linkage. This presentation synopsis covers the rationale, detailed SAR on the optimization process of this linkage vs. others, various synthetic strategies to construct MMI linkage and a brief discussion on the biological properties of the modified oligonucleotides.     

Dynamics of the Rhomboid-like Protein RHBDD2 Expression in Mouse Retina and Involvement of Its Human Ortholog in Retinitis Pigmentosa

The novel rhomboid-like protein RHBDD2 is distantly related to rhomboid proteins, a group of highly specialized membrane-bound proteases that catalyze regulated intramembrane proteolysis. In retina, RHBDD2 is expressed from embryonic stages to adulthood, and its levels show age-dependent changes. RHBDD2 is distinctly abundant in the perinuclear region of cells, and it localizes to their Golgi. A glycine zipper motif present in one of the transmembrane domains of RHBDD2 is important for its packing into the Golgi membranes. Its deletion causes dislodgment of RHBDD2 from the Golgi. A specific antibody against RHBDD2 recognizes two forms of the protein, one with low (39 kDa; RHBDD2_L) and the other with high (117 kDa; RHBDD2_H) molecular masses in mouse retinal extracts. RHBDD2_L seems to be ubiquitously expressed in all retinal cells. In contrast, RHBDD2_H seems to be present only in the outer segments of cone photoreceptors and may correspond to a homotrimer of RHBDD2_L. This protein consistently co-localizes with S- and M-types of cone opsins. We identified a homozygous mutation in the human RHBDD2 gene, R85H, that co-segregates with disease in affected members of a family with autosomal recessive retinitis pigmentosa. Our findings suggest that the RHBDD2 protein plays important roles in the development and normal function of the retina.     

Discovery of a Novel Wolbachia Supergroup in Isoptera

Wolbachia are one of the most abundant groups of bacterial endosymbionts in the biosphere. Interest in these heritable microbes has expanded with the discovery of wider genetic diversity in undersampled host species. Here, we report on the putative discovery of a new genetic lineage, denoted supergroup H, which infects the Isopteran species Zootermopsis angusticollis and Z. nevadensis. Evidence for this novel supergroup is based on portions of new Wolbachia gene sequences from each species spanning 3.5 kilobases of DNA and the following genes: 16S rDNA, dnaA, gltA, groEL, and ftsZ. Single-gene and concatenated maximum likelihood phylogenies establish this new supergroup and validate the positioning of the other Wolbachia supergroups. This discovery is the first example of a termite Wolbachia that is highly divergent from the Isopteran Wolbachia previously described in supergroup F. This study highlights the importance of multilocus approaches to resolving Wolbachia supergroup relationships. It also suggests that surveys of Wolbachia in more earlier-originating (and undersampled) groups of arthropods are more apt to reveal novel genetic diversity.     

Evolutionary Patterns and Selective Pressures of Odorant/Pheromone Receptor Gene Families in Teleost Fishes

Background

Teleost fishes do not have a vomeronasal organ (VNO), and their vomeronasal receptors (V1Rs, V2Rs) are expressed in the main olfactory epithelium (MOE), as are odorant receptors (ORs) and trace amine-associated receptors (TAARs). In this study, to obtain insights into the functional distinction among the four chemosensory receptor families in teleost fishes, their evolutionary patterns were examined in zebrafish, medaka, stickleback, fugu, and spotted green pufferfish.

Methodology/Principal Findings

Phylogenetic analysis revealed that many lineage-specific gene gains and losses occurred in the teleost fish TAARs, whereas only a few gene gains and losses have taken place in the teleost fish vomeronasal receptors. In addition, synonymous and nonsynonymous nucleotide substitution rate ratios (K_A/K_S) in TAARs tended to be higher than those in ORs and V2Rs.

Conclusions/Significance

Frequent gene gains/losses and high K_A/K_S in teleost TAARs suggest that receptors in this family are used for detecting some species-specific chemicals such as pheromones. Conversely, conserved repertoires of V1R and V2R families in teleost fishes may imply that receptors in these families perceive common odorants for teleosts, such as amino acids. Teleost ORs showed intermediate evolutionary pattern between TAARs and vomeronasal receptors. Many teleost ORs seem to be used for common odorants, but some ORs may have evolved to recognize lineage-specific odors.     

Testing Methods: The Evaluation of Discovery Operations in Evolutionary Biology

Scientific discovery requires both abstract, theoretically defined concepts and discovery operations formed by sets of rules that permit the empirical detection of instances of those concepts. In this paper, I examine the ontological status of discovery operations and the tests employed to evaluate them in evolutionary biology. Attention is drawn to the distinction between nomothetic (universal, predictive) and ideographic (historical, retrodictive) discovery operations, and between complementary and exclusive discovery operations. Three types of tests of discovery operations are commonly employed in evolutionary biology. Theoretical tests aim to show that a discovery operation is inconsistent with accepted, well-corroborated, empirical theories. Empirical tests evaluate the performance of competing discovery operations in terms of their results when applied to the same empirical data sets. Philosophical tests aim to show that an operation is inconsistent with logical and epistemological principles. Appropriately designed theoretical and philosophical tests of ideographic discovery operations may be scientifically valid. Empirical tests, however, are incapable of evaluating the scientific merits of competing discovery operations. Nonetheless, empirical comparisons (not tests ) of competing discovery operations may provide insight into the ways discovery operations may be misleading and therefore may play an important role in stimulating critical debate and eventually establishing a scientifically optimal operation. In practice, theoretical and philosophical tests are often combined to test competing discovery operations as rigorously as possible.     

光学分子影像技术及其在药物研发领域的应用

光学分子影像技术是一种发展迅速的生物医学影像技术,能够利用生物发光技术或荧光蛋白等,对生物体内特定的生物过程进行无创的定性或定量研究。应用该技术可以对药物进行筛选,选取具有潜在治疗效果的药物进行后续研究,而终止对可能无效药物的研究,同时可以评价药物对肿瘤的代谢、增殖、血管形成、凋亡和组织乏氧等方面的影响。本文主要介绍光学分子影像技术及其在药物研发,尤其是抗肿瘤药物研发领域的应用。