Changes in thick filament length in Limulus striated muscle

Here we describe the change in thick filament length in striated muscle of Limulus, the horseshoe crab. Long thick filaments (4.0 microns) are isolated from living, unstimulated Limulus striated muscle while those isolated from either electrically or K+-stimulated fibers are significantly shorter (3.1 microns) (P less than 0.001). Filaments isolated from muscle glycerinated at long sarcomere lengths are long (4.4 microns) while those isolated from muscle glycerinated at short sarcomere lengths are short (2.9 microns) and the difference is significant (P less than 0.001). Thin filaments are 2.4 microns in length. The shortening of thick filaments is related to the wide range of sarcomere lengths exhibited by Limulus telson striated muscle.     

Behavior and spatial learning in birds in radial maze

Studies of spatial learning and memory of birds in radial maze are reviewed. The radial maze variants (standard, giant and open-field analog) are described; procedural problems of bird testing are discussed. Radial maze task performance of birds is compared with that of laboratory rats as a well-studied standard. Specific features of spatial learning in various taxonomic avian groups (pigeon, tits, corvids, chickens and others) are considered. The results of spatial memory studies in closely-related species with different ecology (food storing behavior, degree of caching specialization) and experiments with migrant birds and homing pigeons are discussed.     

S-Nitrosothiol measurements in biological systems

S-Nitrosothiol (SNO) cysteine modifications are regulated signaling reactions that dramatically affect, and are affected by, protein conformation. The lability of the SNO bond can make SNO-modified proteins cumbersome to measure accurately. Here, we review methodologies for detecting SNO modifications in biology. There are three caveats. (1) Many assays for biological SNOs are used near the limit of detection: standard curves must be in the biologically relevant concentration range. (2) The assays that are most reliable are those that modify SNO protein or peptide chemistry the least. (3) Each result should be quantitatively validated using more than one assay. Improved assays are needed and are in development.     

秦岭田峪河流域种子植物区系研究

田峪河流域是陕西秦岭植物园的核心区,有种子植物128科,605属,1231种（不含种下等级）。区系分析表明,该流域仍以温带成分为主,占总属的70.96%,热带成分占21.13%,地中海与中亚成分占4.41%,中国特有属占3.5%,稀有濒危植物、单种属和少种属、中国特有属及木本植物均占较大比重,说明了历史起源的古老性,地理成分复杂,联系广泛,分布交错,具有明显的温带特征。     

Pheromonal communication involved in courtship behavior in Diptera

Sex pheromones are known for many dipteran species and play an important role in courtship behavior, together with visual, tactile, acoustic and other factors. Pheromones for a number of dipterans have been recently identified. This survey covers a number of species in all the families that have been studied. The review discusses diverse courtship behaviors in Diptera, with a special focus on the sex pheromones involved. In the Nematocera suborder, pheromones are volatile components, which act at a distance. They are derived from short-chain alkanes with acetoxy groups (Cecidomyidae) or terpenes (Psychodidae). In the Cyclorrhapha, pheromones may be volatile, derived from alkanes (Tephritidae) or terpenes (Agromyzidae), or non-volatile, unsaturated or methyl-branched hydrocarbons, which act by contact (the other subgenera). The behavioral roles and regulation of these pheromones are described, and their importance in species recognition is discussed.     

湖北省爬行动物资源概况

摘要：为了搞清湖北省爬行动物资源概况,通过总结文献资料,并结合作者等最近20余年积累的调查资料,从区系特点、地理分布、评估等级、资源量及保护对策等方面总结了湖北省爬行动物的资源概况。结果显示,湖北省现有爬行动物2目12科44属78种,主要分布在鄂西南（57种,占73.1％）、鄂西北(47种,占60.3％)和鄂东南（43...     

Biliary excretion in foreign compounds. Sulphonamide drugs in the rat

1. The extent of biliary excretion in the rat of 15 sulphonamide compounds was studied. 2. Most of the sulphonamides studied, with molecular weights from 172 (sulphanilamide) to 352 (N⁴-acetylsulphadimethoxine) are poorly excreted in the bile (0–4% of the dose), except sulphapyridine, sulphamethoxypyridazine and sulphadimethoxine. The last three are partly metabolized to glucuronides, whose molecular weights and polarities are such as to allow them to be excreted in the bile in appreciable amounts. 3. Succinylsulphathiazole and phthalylsulphathiazole are polar and have molecular weights (355 and 403) of an appropriate order, and are excreted unchanged in the bile in appreciable amounts. 4. Sulphadimethoxine N¹-glucuronide (mol.wt. 487) is extensively excreted in the bile unchanged. 5. The results are examined in the light of the hypotheses put forward in the preceding paper (Millburn, Smith & Williams, 1967).     

Novel Ribonucleic Acid Species Accumulated in the Dark in the Blue-Green Alga Anacystis nidulans

In the dark, the obligately photoautotrophic blue-green alga Anacystis nidulans accumulates large relative amounts of two novel stable ribonucleic acid species (RNAs). These species are also made in illuminated cells but are unstable in them. When darkened cells are reilluminated, these RNAs are rapidly degraded; degradation is inhibited by chloramphenicol. Upon denaturation with heat or urea, one novel species (0.33 x 10(6) daltons) dissociates into two fragments that comigrate with the second novel species (0.16 x 10(6) daltons) on polyacrylamide gels. Both RNAs are associated with particles sedimenting between 30S and 50S through sucrose gradients and are removed from these particles at low magnesium concentration. The function(s) of these RNAs remains unknown.     

Methods of embryo scoring in in vitro fertilization

It has been 25 years since the introduction of in vitro fertilization (IVF) for treatment of infertility. During this time very dynamic advances have taken place in all aspects of assisted reproductive technology (ART). The rapid improvement in embryological methods, especially these related to preimplantation embryo evaluation are of great importance. This article is a review of embryo classification systems utilized in ART programs. The most widely used scoring systems of zygotes and embryos (including blastocysts) are described. Additionally, the advantages of advanced embryo classifications in relation to ART success rates are presented.     

Interpopulation variation in a fish predator drives evolutionary divergence in prey in lakes

Ecological factors are known to cause evolutionary diversification. Recent work has shown that evolution in strongly interacting predator species has reciprocal impacts on ecosystems. These divergent impacts of predators may alter the selective landscape and cause the evolution of prey. Yet, this link between intraspecific variation and evolution is unexplored. We compared the life history of a species of zooplankton (Daphnia ambigua) from lakes in New England in which the dominant planktivorous predator, the alewife (Alosa pseudoharengus), differs in feeding traits and migratory behaviour. Anadromous alewife (seasonal migrants) exhibit larger gapes, gill-raker spacing and target larger prey than landlocked alewife (year-round freshwater resident). In 'anadromous' lakes, Daphnia are abundant in the spring but extirpated by alewife predation in summer. Daphnia are rare year-round in 'landlocked' lakes. We show that Daphnia from lakes with anadromous alewife grew faster, matured earlier but at the same size and produced more offspring than Daphnia from lakes with landlocked or no alewife across multiple temperature and resource treatments. Our results are inconsistent with a response to size-selective predation but are better explained as an adaptation to colder temperatures and shorter periods of development (countergradient variation) mediated by seasonal alewife predation.     

Somatic gene mutations in vivo as indicated by the 6-thioguanine-resistant T-lymphocytes in human blood

The clonal and the autoradiographic assays for 6-thioguanine-resistant (TG^r) T-lymphocytes (T-Lys) in human blood are reviewed. Studies of TG^r colonies recovered from clonal assays show that the mutant T-Lys (i) are either helper (T4) or suppressor (T8) cells, (ii) poses stable TG^r phenotype, (iii) are deficient in hypoxanthine guanine phosphoribosyltransferase (HPRT), and (iv) have structural alterations in the hprt gene. TG^r T-Ly mutant frequencies (Mfs) determined by clonal assays are of the order of 10⁻⁶−10⁻⁵ for normal adults. Autoradiographically determined variant frequencies (Vfs) are also in this range for normal adults when lymphocytes are cryopreserved before study to remove ‘phenocopies’. Cancer exposed to potentially mutagenic treatments have elevated TG^r T-Ly Vfs. Comparative clonal and autoradiographic assays of the same blood samples give generally similar results when allowances are made for potential sources of error in each assay. The TG^r T-Ly system is presented for human specific-locus mutagenicity monitoring.     

Mosquito-Associated Viruses in China

Mosquitoes are classified into approximately 3500 species and further grouped into 41 genera. Epidemiologically, they are considered to be among the most important disease vectors in the world and they can harbor a wide variety of viruses. Several mosquito viruses are considered to be of significant medical importance and can cause serious public health issues throughout the world. Such viruses are Japanese encephalitis virus (JEV), dengue virus (DENV), chikungunya virus (CHIKV), and Zika virus (ZIKV). Others are the newly recognized mosquito viruses such as Banna virus (BAV) and Yunnan orbivirus (YNOV) with unclear medical significance. The remaining mosquito viruses are those that naturally infect mosquitoes but do not appear to infect humans or other vertebrates. With the continuous development and improvement of mosquito and mosquito-associated virus surveillance systems in China, many novel mosquito-associated viruses have been discovered in recent years. This review aims to systematically outline the history, characteristics, distribution, and/or current epidemic status of mosquito-associated viruses in China.     

Mosaicism in mammals

Summary Eighteen new cases of colour mosaics are described. Previous reports of mosaics are collocated and briefly discussed. Various mechanisms are described which may engender three types of mosaicism. These are the (1) somatic, (2) the soma-gonadic and (3) the gonadic. The first type is the most frequent but representatives of the other two types are not unknown. The analytical study of both spontaneous and induced mosaicism holds promise for the study of cell lineage and tissue dynamics. A possible tendency of white spotting to act as an organiser is noted. The usefulness of the study of mosaicism for analysis of complex loci is touched upon.     

Strong patterns in homooligomer tracts occurrences in non-coding and in potential regulatory sites in eukaryotic genomes

Previous studies of the dinucleotides flanking both the 5' and 3' ends of homooligomer tracts have shown that some flanks are consistently preferred over others (1,2). In the first preferred group, the homooligomer tracts are flanked by the same nucleotide and/or the complementary nucleotides, e.g.,ATAn,TTAn,CCGn, where n = 2-5. Runs flanked by nucleotides with which they cannot base pair are distinctly disfavored. (In this group An/Tn are flanked by C and/or G; Gn/Cn are flanked by A/T, e.g.,CGAn,TnGG,GnAT). The frequencies of runs flanked by A or T, and G or C ("mixed"group) are as expected. Here we seek the origin of this effect and its relevance to protein-DNA interactions. Surprisingly, within the first group, runs flanked by their complements with a pyrimidine-purine junction (e.g.,TTAn,CnGG) are greatly preferred. The frequencies of their purine-pyrimidine junction mirror-images is just as expected. This effect, as well as additional ones enumerated below, is seen universally in eukaryotes and in prokaryotes, although it is stronger in the former. Detailed analysis of regulatory regions shows these strong trends, particularly in GC sequences. The potential relationship to DNA conformation and DNA-protein interaction is discussed.     

Marine Ornamental Trade in Brazil

Brazil is one of the five leading exporting countries of tropical aquarium fishes in the world, and the interest in marine ornamental organisms has increased substantially there from the mid to the late 1990s. About 120 reef fish species are currently harvested in Brazil's ornamental trade. Among the 75 most harvested species, 26 (34.7%) are endemic, eight (10.7%) are rare, and six (8.2%) are estuarine-dependent species. Fifty-five species (75.3%) have complex reproductive strategies and/or parental care. In quantitative terms, the top 10 species comprises 62% of the species exported from Brazil to the USA and the European Community. The most harvested reef invertebrates include about 65 species. The most representative groups are crustaceans with 15 species (23%), and molluscs and stony corals with 10 species (15.4%) each. Among these, 15 (23%) are endemics, nine (13.8%) are rare species, and seven (10.8%) are important reef builders. A case of local extinction of the giant anemone Condylactis gigantea is reported. To alleviate ecological impacts a series of urgent measures is suggested, including the creation of specific laws for marine ornamental harvesting and improving law enforcement to prevent illegal trade in Brazil.     

Peptide-plane flipping in proteins

A peptide-plane flip is a large-scale rotation of the peptide plane that takes the phi,psi angles at residues i and i + 1 to different structural regions in the Ramachandran plot with a comparatively small effect on the relative orientation of their side chains. This phenomenon, which is expected to play an important role during the early stages of protein folding, has been investigated using 76 proteins for which two high-resolution X-ray conformations are available. Peptide-plane flips are identified by looking for those cases where changes in /psi(i)/ + /phi(i + 1)/ are large (>200 degrees), but changes in /psi(i) + phi(i + 1)/ are comparatively small (<50 degrees). Of a total of 23 cases, the most common peptide-plane flip was identified to be the type I to type II beta-turn interconversion. Although individually rarer, there are many other types of flips that are collectively more common. Given the four main accessible regions alpha(R), alpha(L), beta and epsilon, identified from the phi,psi distribution corresponding to non-hydrogen-bonded peptide planes, 32 main types of peptide-plane flip are identified. Only 8 of these are "passive," in that they require only relatively minor adjustments in the orientation of adjacent peptide planes. Of these, only the type I to type II beta-turn interconversion, denoted, beta(i) + alpha(L)(i + 1) <--> alpha(R)(i) + alpha(R)(i + 1), and the rarer alpha(R)(i) + alpha(L)(i + 1) <--> beta(i) + alpha(R)(i + 1), do not involve the epsilon region. "Active" peptide-plane flips affect the orientation of adjacent peptide planes. The flip, alpha(L)(i) + alpha(L)(i + 1) <--> beta(i) + beta(i + 1), of which one example was found, shows how concerted peptide-plane flips can convert the alpha(L) structure to the beta structure without affecting the relative orientations of the side chains.     

Subunits in zonulae adhaerentes and striations in the associated circumferential microfilament bundles in chicken retinal pigment epithelial cells in situ

This study shows that the zonula adhaerens in chicken retinal pigment epithelial (RPE) cells in situ consists of independent subunits which are composed of extracellular intermembrane discs sandwiched between cytoplasmic plaques. These zonula adhaerens complexes (ZACs) are hexagonally arranged within the junction. Previous immunocytochemical studies suggest that the zonula adhaerens region, composed of ZACs, contains the actin associated proteins vinculin and alpha-actinin. The intermembrane discs of ZACs likely mediate cell-to-cell adhesion whereas the cytoplasmic plaques are probably involved in binding the microfilaments of the relatively large circumferential microfilament bundles (CMBs), associated with the zonula adhaerens, to the cell membrane. The CMBs of chicken RPE cells in situ show striations similar to those found in stress fibers of other cell types and in CMBs of cultured epithelial cells. The observation that in the striated regions of CMBs the adjacent junctional membranes tend to follow an undulating path suggests that the CMBs are attached intermittently to the cell membrane and are contractile. The structural similarities between CMBs and stress fibers and the fact that they share similar actin associated proteins support the view that CMBs and stress fibers are related structures.     

Stress and adaptation in conservation genetics

Stress, adaptation and evolution are major concerns in conservation biology. Stresses from pollution, climatic changes, disease etc. may affect population persistence. Further, stress typically occurs when species are placed in captivity. Threatened species are usually managed to conserve their ability to adapt to environmental changes, whilst species in captivity undergo adaptations that are deleterious upon reintroduction into the wild. In model studies using Drosophila melanogaster, we have found that; (a) inbreeding and loss of genetic variation reduced resistance to the stress of disease, (b) extinction rates under inbreeding are elevated by stress, (c) adaptive evolutionary potential in an increasingly stressful environment is reduced in small population, (d) rates of inbreeding are elevated under stressful conditions, (e) genetic adaptation to captivity reduces fitness when populations are reintroduced into the 'wild', and (f) the deleterious effects of adaptation on reintroduction success can be reduced by population fragmentation.     

BMP antagonists: their roles in development and involvement in pathophysiology

Bone morphogenetic proteins (BMPs) are phylogenetically conserved signaling molecules that belong to the transforming growth factor (TGF)-beta superfamily, and are involved in the cascades of body patterning and morphogenesis. The activities of BMPs are precisely regulated by certain classes of molecules that are recently recognized as BMP antagonists. BMP antagonists function through direct association with BMPs, thus prohibiting BMPs from binding their cognate receptors. In this review, the classification and functions of BMP antagonists will be discussed, especially focusing on the new family of tissue-specific BMP antagonists composed of uterine sensitization-associated gene 1 (USAG-1) and sclerostin.