Vertebrate cranial evolution: Contributions and conflict from the fossil record

In modern vertebrates, the craniofacial skeleton is complex, comprising cartilage and bone of the neurocranium, dermatocranium and splanchnocranium (and their derivatives), housing a range of sensory structures such as eyes, nasal and vestibulo-acoustic capsules, with the splanchnocranium including branchial arches, used in respiration and feeding. It is well understood that the skeleton derives from neural crest and mesoderm, while the sensory elements derive from ectodermal thickenings known as placodes. Recent research demonstrates that neural crest and placodes have an evolutionary history outside of vertebrates, while the vertebrate fossil record allows the sequence of the evolution of these various features to be understood. Stem-group vertebrates such as Metaspriggina walcotti (Burgess Shale, Middle Cambrian) possess eyes, paired nasal capsules and well-developed branchial arches, the latter derived from cranial neural crest in extant vertebrates, indicating that placodes and neural crest evolved over 500 million years ago. Since that time the vertebrate craniofacial skeleton has evolved, including different types of bone, of potential neural crest or mesodermal origin. One problematic part of the craniofacial skeleton concerns the evolution of the nasal organs, with evidence for both paired and unpaired nasal sacs being the primitive state for vertebrates.     

Cranial cartilages: Players in the evolution of the cranium during evolution of the chordates in general and of the vertebrates in particular

The present contribution is chiefly a review, augmented by some new results on amphioxus and lamprey anatomy, that draws on paleontological and developmental data to suggest a scenario for cranial cartilage evolution in the phylum chordata. Consideration is given to the cartilage-related tissues of invertebrate chordates (amphioxus and some fossil groups like vetulicolians) as well as in the two major divisions of the subphylum Vertebrata (namely, agnathans, and gnathostomes). In the invertebrate chordates, which can be considered plausible proxy ancestors of the vertebrates, only a viscerocranium is present, whereas a neurocranium is absent. For this situation, we examine how cartilage-related tissues of this head region prefigure the cellular cartilage types in the vertebrates. We then focus on the vertebrate neurocranium, where cyclostomes evidently lack neural-crest derived trabecular cartilage (although this point needs to be established more firmly). In the more complex gnathostome, several neural-crest derived cartilage types are present: namely, the trabecular cartilages of the prechordal region and the parachordal cartilage the chordal region. In sum, we present an evolutionary framework for cranial cartilage evolution in chordates and suggest aspects of the subject that should profit from additional study.     

Evolutionary and developmental origins of the cardiac neural crest: Building a divided outflow tract

The cardiac neural crest cells (CNCCs) have played an important role in the evolution and development of the vertebrate cardiovascular system: from reinforcement of the developing aortic arch arteries early in vertebrate evolution, to later orchestration of aortic arch artery remodeling into the great arteries of the heart, and finally outflow tract septation in amniotes. A critical element necessary for the evolutionary advent of outflow tract septation was the co‐evolution of the cardiac neural crest cells with the second heart field. This review highlights the major transitions in vertebrate circulatory evolution, explores the evolutionary developmental origins of the CNCCs from the third stream cranial neural crest, and explores candidate signaling pathways in CNCC and outflow tract evolution drawn from our knowledge of DiGeorge Syndrome. Birth Defects Research (Part C) 102:309–323, 2014. © 2014 Wiley Periodicals, Inc.     

The mouse Dlx-2 (Tes-1) gene is expressed in spatially restricted domains of the forebrain, face and limbs in midgestation mouse embryos

The pattern of RNA expression of the murine Dlx-2 (Tes-1) homeobox gene is described in embryos ranging in age from E8.5 through E11.5. Dlx-2 is a vertebrate homologue of the Drosophila Distal-less (Dll) gene. Dll expression in the Drosophila embryo is principally limited to the primordia of the brain, head and limbs. Dlx-2 is also expressed principally in the primordia of the forebrain, head and limbs. Within these regions it is expressed in spatially restricted domains. These include two discontinuous regions of the forebrain (basal telencephalon and ventral diencephalon), the branchial arches, facial ectoderm, cranial ganglia and limb ectoderm. Several mouse and human disorders have phenotypes which potentially are the result of mutations in the Dlx genes.     

Expression of AmphiCoe, an amphioxus COE/EBF gene, in the developing central nervous system and epidermal sensory neurons

The COE/EBF gene family marks a subset of prospective neurons in the vertebrate central and peripheral nervous system, including neurons deriving from some ectodermal placodes. Since placodes are often considered unique to vertebrates, we have characterised an amphioxus COE/EBF gene with the aim of using it as a marker to examine the timing and location of peripheral neuron differentiation. A single COE/EBF family member, AmphiCoe, was isolated from the amphioxus Branchiostoma floridae. AmphiCoe lies basal to the vertebrate COE/EBF genes in molecular phylogenetic analysis, suggesting that the duplications that formed the vertebrate COE/EBF family were specific to the vertebrate lineage. AmphiCoe is expressed in the central nervous system and in a small number of scattered ectodermal cells on the flanks of neurulae stage embryos. These cells become at least largely recessed beneath the ectoderm. Scanning electron microscopy was used to examine embryos in which the ectoderm had been partially peeled away. This revealed that these cells have neuronal morphology, and we infer that they are the precursors of epidermal primary sensory neurons. These characters lead us to suggest that differentiation of some ectodermal cells into sensory neurons with a tendency to sink beneath the embryonic surface represents a primitive feature that has become incorporated into placodes during vertebrate evolution.     

河北3产地日本三角涡虫的染色体变异与核型多样性分析

利用空气干燥法,对采自河北省邯郸市漳河、朝阳湖和邢台市秦王湖3产地日本三角涡虫(Dugesiajaponica)染色体核型进行了研究,结果表明,日本三角涡虫漳河种群与秦王湖种群体细胞中染色体数目以16条为主(2n=2x=16=16m),分别占81.07%和68.47%,少数为24条(2n=3x=24=24m),分别占8.28%和11.71%,为二倍体和三倍体的混合倍体;日本三角涡虫朝阳湖种群体细胞中染色体数目以24条为主(2n=3x=24=24m),占64.60%,少数为16条(2n=2x=16=16m),占7.45%,为三倍体和二倍体的混合倍体。值得注意的是朝阳湖种群部分体细胞中染色体在结构上发生变异,使其核型呈现多型性。文中根据核型分析结果对上述3产地日本三角涡虫染色体及核型的多样性作了初步讨论。     

On the Head Morphology and Systematic Position of Helophorus (Coleoptera: Hydrophiloidea: Helophoridae)

External and internal features of the head of adults of Helophorus spp. were examined and described in detail. The 6 species under consideration show very little morphological variation. The only distinctive characters, which characterise groups of species, are the presence or absence of the mandibular retinaculum and the symmetric or asymmetric shape of the ultimate maxillary palpomere. Helophoridae is supported by several autapomorphies, e.g. a group of long hairs on the posterodorsal margin of galeomere II and the distinctly serrate hind margin of the right mola. Characters with a potential phylogenetic relevance are listed, presented as a data matrix and analysed cladistically. The monophyly of Hydrophiloidea + Histeroidea, Hydrophiloidea (excl. Hydraenidae), ((Helophoridae + Hydrochidae) + (Georissidae [+ Epimetopidae?])), Hydrophilidae and Sphaeridiinae was supported in all trees. The position of Spercheus remains ambiguous. It is either the sistergroup of the remaining Hydrophiloidea or of Hydrophilidae. Head structures of adults of Helophoridae and Hydrochidae show a remarkable similarity. The following apomorphic character states are shared by both taxa: dorsal side of labrum divided into 2 areas with different surface structure, mentum with 2 longitudinal ridges. A clade comprising these 2 families + Georissidae (and probably Epimetopidae) is supported by the metallic granulation of the dorsal side of the head capsule and a grooved frontoclypeal suture. The presence of tubular mandibular glands may be a derived groundplan feature of Hydrophiloidea + Histeroidea. The proposed interrelationships are partly in contrast to current hypothesis. The hypothesised character evolution may change, if a more extensive set of taxa (e.g. Horelophinae, Horelophopsinae) and characters, especially larval features are used (e.g. stigmatic atrium). Several derived characteristics of the clades listed above may have been secondarily lost in Hydrophilidae.     

Developmental and pathogen-induced activation of an msr gene, str246C, from tobacco involves multiple regulatory elements

A family of genes, the so-called msr genes (multiple stimulus response), has recently been identified on the basis of sequence homology in various plant species. Members of this gene family are thought to be regulated by a number of environmental or developmental stimuli, although it is not known whether any one member responds more specifically to one stimulus, or whether each gene member responds to various environmental stimuli. In this report, we address this question by studying the tobacco msr gene str246C. Using transgenic tobacco plants containing 2.1 kb of 5 flanking DNA sequence from the str246C gene fused to the -glucuronidase (GUS) coding region, the complex expression pattern of the str246C promoter has been characterized. Expression of the str246C promoter is strongly and rapidly induced by bacterial, fungal and viral infection and this induction is systemic. Elicitor preparations from phytopathogenic bacteria and fungi activate the str246C promoter to high levels, as do wounding, the application of auxin, auxin and cytokinin, salicylic acid or copper sulfate, indicating the absence of gene specialization within the msr gene family, at least for str246C. In addition, GUS activity was visualized. histochemically in root meristematic tissues of tobacco seedlings and is restricted to roots and sepals of mature plants. Finally, analysis of a series of 5 deletions of the str246C promoter-GUS gene fusion in transgenic tobacco plants confirms the involvement of multiple regulatory elements. A region of 83 by was found to be necessary for induction of promoter activity in response to Pseudomonas solanacearum, while auxin inducibility and root expression are apparently not controlled by this element, since its removal does not abolish either response. An element of the promoter with a negative effect on promoter activation by P. solanacearum was also identified.Joint first authors     

Life history of the ghost shrimp, Callianassa japonica Ortmann (Decapoda: Thalassinidea), on an intertidal sandflat in western Kyushu, Japan

Growth, density, survival, and reproduction were examined for the population of the ghost shrimp, Callianassa japonica Ortmann, inhabiting an intertidal sandflat in western Kyushu, Japan, based on samples collected from May, 1989 to April, 1991. During the breeding season (June–October) each year, there were two discrete periods of egg production by females. The post-larval settlement, with a time-lag of 1–1.5 months (brooding plus larval developmental periods), generated two major recruitment cohorts, occurring in July–August (1st cohort) and September–November (2nd cohort). The higher growth rate of individuals after recruitment in the 1st cohort enhanced the separation of the two cohorts. Between sexes, the subsequent life history patterns and population characteristics were, for the most part, similar. In females, the majority of individuals of each of the two cohorts matured after approximately one year, respectively, at around a 20-mm total body length, and a portion of these cohorts survived as a fused cohort until June of the second year, breeding again prior to dying off by the end of September. The pattern of growth was an indeterminate type. For each of the two cohorts, the growth rates changed at two transition points of their life history, at around the beginning of their two breeding seasons. The growth rate for the 1st cohort slowed down at the first transition point, while that for the 2nd cohort speeded up there. This led to the approach and fusion of the two cohorts near the second transition point, when growth stopped. During periods other than the breeding seasons, high survival rates were exhibited by the two cohorts. During the first breeding season, a significantly low survival rate was observed for the 1st cohort, but not for the 2nd cohort. The degree of participation in breeding activity may be responsible for the above differences between cohorts. In the two male cohorts, while the cost of reproduction did not reduce the growth rates during the first breeding season, it lowered their survival rates more severely compared to those of females. This may be responsible for the slightly female-biased sex ratio in the population (1.06:1). The density of the population as a whole was stable throughout the study period, with the mean ± SD being 901 ± 157/m² (n = 27); the adult population declines during the breeding seasons were effectively replenished by recruitment each year.     

Effect of salinity, temperature, organic and inorganic nutrients on growth of cultured Fibrocapsa japonica (Raphidophyceae) from the northern Adriatic Sea

The effects of temperature, salinity, inorganic and organic nutrients on the growth and physiological performance of Fibrocapsa japonica have been investigated in strains isolated from the northern Adriatic Sea, where intense and regular blooms have occurred since 1997 in coastal waters during summer. Strains isolated at different times and from different locations appeared homogeneous in terms of both physiological responses and molecular (ITS-5.8S rDNA) characteristics. Growth rates were higher at temperatures between 20 and 26 °C and in a salinity range of 30–35 (0.7 div day⁻¹). The temperature of 16 °C inhibited growth, more markedly at the lowest and highest salinity values, a result also confirmed by a lower photosynthetic efficiency and by an increase in cell volume due to impaired division. Higher cell concentrations were obtained with macronutrients at f/2 levels than in a fivefold diluted medium. Comparing the utilization of 200 μM nitrate to that of different N sources (inorganic and organic), F. japonica showed an efficient growth with equivalent amounts of ammonia, urea and amino acids, such as glycine and tryptophan; glutamate was less effective, while methionine had toxic effects. Organic phosphate, administered as glycerophosphate, could also sustain F. japonica growth, probably on account of an alkaline phosphatase whose activity was enhanced in the presence of the organic form. Vitamins were necessary for growth, though no further stimulation was observed when a surplus of vitamin B12 (3 nM) was added. The addition of 11.7 μM iron instead of 2.3 μM, as well as that of humic acid, with or without macronutrients, did not enhance algal growth either. These results led us to hypothesise that F. japonica blooms became more frequent due to a general seawater temperature increase and to the availability of organic forms which, in coastal anthropized areas, are especially abundant in summer periods.     

Morphology and number of Ommatidia in the compound eyes of Solenopsis invicta, Solenopsis richteri, and their hybrid (Hymenoptera: Formicidae)

The morphology and number of ommatidia of the compound eyes of Solenopsis invicta, Solenopsis richteri and their hybrid are investigated. Comparisons are made of the morphology and number of ommatidia in S. invicta, S. richteri and their hybrid. Major workers have significantly more facets than minor workers, male reproductive more than female reproductive, and the reproductives more than workers. Workers and reproductives have significantly more ommatidia in S. invicta than in S. richteri and significantly fewer in the hybrid than in either species. The major workers of each species have significantly wider facets than the minor workers, and workers have significantly wider facets than reproductives, which showed no difference in their facet diameter. There are no significant differences when the facet diameter is compared between the members of the castes of different species. These morphological and numerical dissimilarities are discussed in connection with known behavioral differences in the castes.     

编码腈水解酶的大豆疫霉基因PsNIA的克隆与转录分析

包括大豆在内的许多植物都可以产生氰化物,对侵染的病原菌产生毒害作用而阻碍其进一步扩展。采用抑制性差减杂交(suppression subtractive hybridization,SSH)的方法,筛选到一个在大豆疫霉侵染早期上调表达的、编码腈水解酶的cDNA片段;克隆了该基因的全长序列,命名为PsNIA。Southern杂交结果显示,PsNIA在大豆疫霉基因组中只有1个拷贝。系统发育分析表明,PsNIA与绿脓杆菌Pseudomonas aeruginosa的腈水解酶的序列同源性最高,且该基因编码的氨基酸序列具有腈水解酶的保守结构域。RT-PCR分析表明,该基因在大豆疫霉侵染大豆12h时可以检测到转录。     

编码腈水解酶的大豆疫霉基因PsNIA的克隆与转录分析

包括大豆在内的许多植物都可以产生氰化物,对侵染的病原菌产生毒害作用而阻碍其进一步扩展。采用抑制性差减杂交(suppression subtractive hybridization,SSH)的方法,筛选到一个在大豆疫霉侵染早期上调表达的、编码腈水解酶的cDNA片段;克隆了该基因的全长序列,命名为PsNIA。Southern杂交结果显示,PsNIA在大豆疫霉基因组中只有1个拷贝。系统发育分析表明,PsNIA与绿脓杆菌Pseudomonas aeruginosa的腈水解酶的序列同源性最高,且该基因编码的氨基酸序列具有腈水解酶的保守结构域。RT-PCR分析表明,该基因在大豆疫霉侵染大豆12h时可以检测到转录。     

Leptodiscaceans (Noctilucales, Dinophyceae) from the Pacific Ocean: First records of Petalodinium and Leptodiscus beyond the Mediterranean Sea

Records of dinoflagellates of the family Leptodiscaceae (Noctilucales) from the Kuroshio Current, Philippine, Celebes, Sulu, South China Seas and the western and central Equatorial Pacific Ocean are described. Scaphodinium mirabile was the most common leptodiscacean. Two specimens that differed from the type species of Scaphodinium were found: one specimen showed a highly bifurcate proximal extremity and another showed two dissimilar proboscides from the distal extremity. Another unidentified leptodiscacean showed an arrowhead-shaped contour with the margins folded. Six specimens of Petalodinium porcelio were found, being the first record beyond the Mediterranean-Black Seas. Six specimens were tentatively assigned to the genus Leptodiscus, being the first record beyond the western Mediterranean Sea. The folded specimens that ranged from 90 to 120 μm in diameter and with a prominent flagellum were tentatively considered to be young specimens of Leptodiscus. The abundance of the leptodiscaceans is underestimated in the world's oceans.     

Host range of an NPV and a GV isolated from the common cutworm, Agrotis segetum: pathogenicity within the cutworm complex

The term cutworm covers a range of species with a similar life history that can be very damaging pests on a wide range of crops. Attacks by cutworms are often made up of more than one species; thus, the most cost effective microbial control agent needs to be pathogenic for multiple species within this complex. In this study we investigate the host range of Agrotis segetum NPV and A. segetum GV for other cutworm species and closely related Noctuinae. Eight species, A. segetum, Agrotis ipsilon, Agrotis exclamationis, Agrotis puta, Noctua comes, Peridroma saucia, Xestia sexstrigata, and Xestia xanthographa, were clearly susceptible to AgseNPV, which was confirmed by DNA analysis. Aglais urticae, Diarsia rubi, Noctua pronuba, and Xestia c-nigrum were not susceptible to AgseNPV at the doses used. Noctua fimbriata, Noctua janthina, and Ochroplura plecta gave ambivalent results: larvae died of NPV infection when they were challenged with AgseNPV, but these individuals only produced weak positives in a squash blot analysis and there was insufficient DNA for confirmation by restriction endonuclease profiling. These ambivalent results could suggest either a weak infection by AgseNPV or partial homology between their own virus and AgseNPV. The untreated control insects of several species died of NPV infection, which indicates that these field-collected insects were probably carrying a vertically transmitted NPV. Fewer species were tested with AgseGV and only N. pronuba and N. comes were susceptible. N. fimbriata and Helicoverpa armigera were not susceptible to AgseGV.     

尖吻蝮蛇未知C类凝集素蛋白cDNA扩增、克隆与表达

蛇毒中C类凝集素(C-TLs)超家族蛋白,是具有抗凝血等功能的一族蛋白质.根据测得的蛇毒蛋白的N端氨基酸序列,设计PCR引物;从湖南尖吻蝮蛇毒腺中提取总RNA,经反转录,再通过温度降落锚式PCR,在只使用一个特异性引物和一个通用引物、进行一次循环数不超过30的非巢式反应的条件下,即获得两个较为清晰的扩增条带;其中之一带经克隆、测序、比较,证明其与已知的蛇毒中C类凝集素超家族蛋白质有较高的同源性.在大肠杆菌中获得高效融合表达,融合蛋白占细胞总蛋白的26%～30%.     

Morphology and toxicology of Prorocentrum arabianum sp. nov., (dinophyceae) a toxic planktonic dinoflagellate from the Gulf of Oman, Arabian Sea

A new species of planktonic dinoflagellate, Prorocentrum arabianum isolated from the Gulf of Oman, is described using both scanning electron microscopy (SEM) and light microscopy. This clonal isolate has the following morphological characteristics: (1) cell shape is asymmetric; (2) thecal surface is rugose, covered with small poroids; (3) periflagellar area is unornamented, and (4) intercalary band is horizontally striated. Analysis of P. arabianum confirms the production of one cytotoxic compound and one ichthyotoxic compound. P. arabianum is the second known toxic planktonic Prorocentroid dinoflagellate.     

Incidence of the introduced parasitoids Cotesia kazak and Microplitis croceipes (Hymenoptera: Braconidae) from Helicoverpa armigera (Lepidoptera: Noctuidae) in tomatoes, sweet corn, and lucerne in New Zealand

Morphological defense traits of plants such as trichomes potentially compromise biological control in agroecosystems because they may hinder predation by natural enemies. To investigate whether plant trichomes hinder red imported fire ants, Solenopsis invicta Buren (Hymenoptera: Formicidae), as biological control agents in soybean, field and greenhouse experiments were conducted in which we manipulated fire ant density in plots of three soybean isolines varying in trichome density. Resulting treatment effects on the abundance of herbivores, other natural enemies, plant herbivory, and yield were assessed. Trichomes did not inhibit fire ants from foraging on plants in the field or in the greenhouse, and fire ant predation of herbivores in the field was actually greater on pubescent plants relative to glabrous plants. Consequently, fire ants more strongly reduced plant damage by herbivores on pubescent plants. This effect, however, did not translate into greater yield from pubescent plants at high fire ant densities. Intraguild predation by fire ants, in contrast, was weak, inconsistent, and did not vary with trichome density. Rather than hindering fire ant predation, therefore, soybean trichomes instead increased fire ant predation of herbivores resulting in enhanced tritrophic effects of fire ants on pubescent plants. This effect was likely the result of a functional response by fire ants to the greater abundance of caterpillar prey on pubescent plants. Given the ubiquity of lepidopteran herbivores and the functional response to prey shown by many generalist arthropod predators, a positive indirect effect of trichomes on predation by natural enemies might be more far more common than is currently appreciated.     

A novel method for the cloning of chromosomal mutations in a single step: Isolation of two mutant alleles of envZ, an osmoregulatory gene from Escherichia coli

Summary We have developed a simple, rapid and powerful method for the cloning of chromosomal mutations from total cellular DNA in a single step using a plasmid carrying the clined wild-type locus of interest and a convenient selectable marker such as antibiotic resistance. This method relies upon the ability of the cloned wild-type gene to form a heteroduplex with the mutant chromosomal locus. The plasmid from primary transformants can be screened rapidly by size; more than 50% of plasmids of the correct size contained the mutant locus. When this method was used to clone two chromosomal mutations in the envZ gene of Escherichia coli, a locus which encodes a membrane-bound sensory protein involved in the osmoregulation of outer membrane porin biosynthesis, more than 50% of the retransformants from the plasmids selected by size were found to exhibit the mutant phenotype. Preliminary characterization of these mutant alleles is discussed. This novel and powerful method should be generally applicable in any system where the cloned locus is available.This work was presented at the 86th Annual Meeting of the American Society for Microbiology, March 1986, Washingnton, D.C.