Steering Between Scylla and Charybdis: The Northwest Passage as Territorial Sea

Heightened attention is being paid to the Northwest Passage, the waters that flow among the islands of northern Canada and that, in the next decades, may be amenable to commercial navigation. Most debates regarding the Passage's legal status focus on Canada's contention that it is its internal waters and the United States’ contention that it is an international strait. This article proposes that a designation of the Passage as Canada's territorial sea would be as legally robust as the internal waters or international strait designations while satisfying both Canada's and the United States’ political objectives.     

Between Scylla and Charybdis: renegotiating resolution of the ‘obstetric dilemma’ in response to ecological change

Hominin evolution saw the emergence of two traits—bipedality and encephalization—that are fundamentally linked because the fetal head must pass through the maternal pelvis at birth, a scenario termed the ‘obstetric dilemma’. While adaptive explanations for bipedality and large brains address adult phenotype, it is brain and pelvic growth that are subject to the obstetric dilemma. Many contemporary populations experience substantial maternal and perinatal morbidity/mortality from obstructed labour, yet there is increasing recognition that the obstetric dilemma is not fixed and is affected by ecological change. Ecological trends may affect growth of the pelvis and offspring brain to different extents, while the two traits also differ by a generation in the timing of their exposure. Two key questions arise: how can the fit between the maternal pelvis and the offspring brain be ‘renegotiated’ as the environment changes, and what nutritional signals regulate this process? I argue that the potential for maternal size to change across generations precludes birthweight being under strong genetic influence. Instead, fetal growth tracks maternal phenotype, which buffers short-term ecological perturbations. Nevertheless, rapid changes in nutritional supply between generations can generate antagonistic influences on maternal and offspring traits, increasing the risk of obstructed labour.     

Locomotor Dysfunction and Pain: The Scylla and Charybdis of Fiber Sprouting After Spinal Cord Injury

Injury to the spinal cord (SCI) can produce a constellation of problems including chronic pain, autonomic dysreflexia, and motor dysfunction. Neuroplasticity in the form of fiber sprouting or the lack thereof is an important phenomenon that can contribute to the deleterious effects of SCI. Aberrant sprouting of primary afferent fibers and synaptogenesis within incorrect dorsal horn laminae leads to the development and maintenance of chronic pain as well as autonomic dysreflexia. At the same time, interruption of connections between supraspinal motor control centers and spinal cord output cells, due to lack of successful regenerative sprouting of injured descending fiber tracts, contributes to motor deficits. Similarities in the molecular control of axonal growth of motor and sensory fibers have made the development of cogent therapies difficult. In this study, we discuss recent findings related to the degradation of inhibitory barriers and promotion of sprouting of motor fibers as a strategy for the restoration of motor function and note that this may induce primary afferent fiber sprouting that can contribute to chronic pain. We highlight the importance of careful attentiveness to off-target molecular- and circuit-level modulation of nociceptive processing while moving forward with the development of therapies that will restore motor function after SCI.     

Reference gene and tropomyosin expression in mud crab Scylla olivacea,Scylla paramamosain and Scylla tranquebarica

Molecular Biology Reports - Tropomyosin, a muscle tissue protein is a major allergen in most of shellfish including mud crab. Quantitative real time-PCR (qRT-PCR) using a stable reference gene is...     

Purification and characterization of phenoloxidase from crab Charybdis japonica

Phenoloxidase (PO) from hemolymph of Charybdis japonica was purified by gel-filtration and ion-exchange chromatography, and characterized in terms of its molecular mass and enzymatic properties by using L-dihydroxyphenylalanine (L-DOPA) as the specific substrate. It was found that prophenoloxidase (proPO), isolated as a monomeric protein, had a molecular mass of 69.5 kDa, and a 64.5 kDa PO molecule was often contained in preparations. The PO activity showed optimal pH of 6.0, optimal temperature of 40 degrees C, and an apparent Km value of 3.41 on L-DOPA, and 7.97 on catechol. PO activity was extremely sensitive to sodium sulfite and 1-phenyl-2-thiourea, and very sensitive to thiourea and benzoic acid. Based on its inhibition characteristics and the substrate affinity, this PO was classified as a kind of o-diphenoloxidase. The PO activity was also strongly inhibited by Zn(2+), Mg(2+), ethylenediaminetetraacetic acid (EDTA) and diethyldithiocarbamate (DETC). The results with EDTA, DETC, and some metal ions, combined with the perfect recovery effect of Cu(2+) on DETC-inhibited PO activity, indicate that Charybdis PO is most probably a copper-containing metalloenzyme.     

食物条件对日本蟳幼体存活与变态的影响

This paper studied the effects of different kind and density of baits and different starvation duration on Charybdis japonica larvae. The results showed that the preferable baits of zoaea-1 were Chaetoceros sp. and Isochysisgalbana, and their proper feeding density were 20 × 10^4 cell· ml^-1. The preferable bait of the larvae after zoaea-1 was Artemia salina nauplius, and its proper feeding density for zoaea-2 and zoaea-3 was 2 - 3 ind· ml^-1. The point of no-return for zoaea-1 of Charybdisjapoptica was about 66 hours. 18 hours starvation did not affect the growth of the larvae, but their livability would be decreased, and their metamorphism would be suspended along with the starvation duration.     

Identification and characterization of a hemocyanin-derived phenoloxidase from the crab Charybdis japonica

To determine effective activators of crab hemocyanin (Hc) and the properties of Hc-derived phenoloxidase (HdPO), Hc, for the first time, was purified from hemolymph of Charybdis japonica, and the properties of activated HdPO were studied by using L-DOPA as a substrate. Three distinct subunits were isolated, and each had a molecular mass of about 80, 75 and 70 kDa, respectively. SDS and HLS were much effective in conversion of Hc into HdPO whose PO activity was optimal at pH 7.0 and temperature of 40 °C. The Km value of the HdPO was 2.90 mM for L-DOPA and 7.33 mM for tyrosine. The PO activity of HdPO was most sensitive to 1-phenyl-2-thiourea, cysteine and ascorbic acid, and much sensitive to thio urea and sodium sulfite. Based on its inhibition characteristics and the substrate specificity, this HdPO could be classified as a kind of tyrosinase-type phenoloxidase. The PO activity of HdPO was also strongly inhibited by Cu²⁺, Zn²⁺, ethylenediaminetetraacetic acid (EDTA) and diethyldithiocarbamate (DETC). The results with EDTA, DETC, and some metal ions, combined with the perfect recovery effect of Cu²⁺ on DETC-inhibited PO activity, indicate that the HdPO is a kind of copper-containing metalloenzyme. All these imply that the Hc, as an oxygen carrier, can be activated to have PO activities by SDS or HLS, and the activated HdPO has the properties of a tyrosinase-type copper-containing phenoloxidase. This study makes us to understand more easily the multifunctions of crustacean Hc in oxygen carrier and melaninization at certain stresses in host defence as well.     

Micropropagation of squill (Charybdis numidica) through nodule culture

A micropropagation protocol for squill (Charybdis numidica, Hyacinthaceae) was developed using nodule culture. Nodule formation on leaf sections was induced in liquid Murashige and Skoog (MS) medium supplemented with 20 microM N6-benzylaminopurine (BA) under dark conditions. Nodules were cultured on semi-solid MS medium with factorial combinations of BA (0-40 microM) and alpha-naphthaleneacetic acid (NAA) (0-10 microM) under continuous light. Shoot regeneration from nodules occurred at varying degrees on all media. The highest number of shoots was formed on medium containing 2.5 microM NAA and 20 microM BA, while the maximum number of regenerated bulblets per gram nodule was induced on culture medium supplemented with 2.5 microM NAA alone. Regenerated shoots were successfully rooted at approximately 92% on semi-solid MS medium supplemented with 10 microM indole-3-acetic acid (IAA). Plantlets could be hardened and grew well after transfer to the greenhouse. Chemical analyses showed consistent bufadienolide patterns from cloned plantlets and the mother plant.     

青蟹线粒体COI假基因的分离和特征分析

线粒体DNA标记在遗传结构和系统进化研究中得到广泛应用,然而核假基因的存在对此有很大威胁。本文以中国东南沿海的青蟹(Scylla paramamosain)为研究对象,利用线粒体COI基因的通用引物和特异性引物进行扩增,分别得到34个假基因（nuclear mitochondrial pseudogenes, Numts）和5个线粒体COI基因序列。在所获得的34个假基因中共定义了29种单倍型,根据序列的相似度,这些假基因可以分为2类,每类假基因都有各自保守的核苷酸序列。第Ⅰ类假基因存在2处插入序列和1处8 bp的缺失序列,这些位点导致了整个阅读框的移位;在第Ⅱ类假基因和5个线粒体COI序列中只有碱基替换,未发现插入和缺失序列。实验结果分析表明,这两类假基因分别代表了2次核整合事件,即核转移事件的最低值。研究结果提示了     

From Scilla to Charybdis – is our voyage safer now?

The genus Charybdis Speta (previously Urginea maritima agg.) was investigated karyologically and genetically throughout its geographic range in the Mediterranean. The different ploidy levels show a strong geographic pattern. Diploid populations are mainly found along the northern coast of Africa with C. pancration extending northwards from Tunisia to southern Italy. Tetraploid populations are most densely distributed in the eastern Mediterranean but are also found in North Africa, on the Balearic and Canary Islands. Hexaploid populations are restricted to the Iberian Peninsula and adjacent Morocco and Algeria. Chloroplast microsatellite data suggest that determination of ploidy levels alone is insufficient to adequately describe the existing populations. Especially the tetraploid and hexaploid populations exhibit additional genetic differentiation and geographic structuring. AFLP data indicate that tetraploid populations from southern Italy are of hybrid origin. Phylogenetic analysis further revealed that the genera Urginea Steinh. and Charybdis are not directly related to each other but have strong ties to genera from southern Africa. A possible colonization scenario of the Mediterranean via NW Africa and Iberia is discussed.     

Ribosomal DNA Intergenic Spacer of the Swimming Crab, Charybdis japonica

We have determined the full sequence of the ribosomal DNA intergenic spacer (IGS) of the swimming crab, Charybdis japonica, by long PCR for the first time in crustacean decapods. The IGS is 5376 bp long and contains two nonrepetitive regions separated by one long repetitive region, which is composed mainly of four subrepeats (subrepeats I, II, III, and IV). Subrepeat I contains nine copies of a 60-bp repeat unit, in which two similar repeat types (60 bp-a and 60 bp-b) occur alternatively. Subrepeat II consists of nine successive repeat units with a consensus sequence length of 142 bp. Subrepeat III consists of seven copies of another 60-bp repeat unit (60 bp-c) whose sequence is complementary to that of subrepeat I. Immediately downstream of subrepeat III is subrepeat IV, consisting of three copies of a 391-bp repeat unit. Based on comparative analysis among the subrepeats and repeat units, a possible evolutionary process responsible for the formation of the repetitive region is inferred, which involves the duplication of a 60-bp subrepeat unit (60 bp-c) as a prototype. Received: 13 April 1999 / Accepted: 2 August 1999     

A spectroscopic study of rat liver and Scylla serrata crab metallothioneins

The absorption, circular dichroism (CD) and magnetic circular dichroism (MCD) spectra of native rat liver and crab (Scylla serrata) Cd,Zn-metallothionein have been measured and the data are compared. The MCD data indicate that there are close similarities in the geometries of the cadmium-binding sites in both of these proteins; however, the CD spectra are quite different for the rat liver and crab proteins. The CD spectrum for the crab metallothionein is unlike any previously reported for a cadmium-containing metallothionein. This suggests that the CD spectrum is sensitive to the different bridging pattern used in the binding sites in the crab compared with the rat-liver metallothionein. Cadmium binding to the metal-free metallothionein is demonstrated for both proteins and it is shown that there are only minor structural differences between the native and remetallated proteins. The structural changes that occur near to the cadmium-binding sites during cadmium loading to the native proteins have been followed using absorption and CD spectroscopy. Marked changes are observed in the CD spectrum which can be associated with a two-phase reaction: initially Zn2+ is displaced by the Cd2+, then at higher concentrations of Cd2+ the tetrahedral geometry of the Cd2+-binding sites is lost as more Cd2+ is bound using the same thiolate groups. While this latter reaction results in considerable change to the CD spectrum, only minor changes are observed in the absorption spectrum. A significant red shift is observed in the S leads to Cd charge transfer transition region of the MCD spectrum (230-270 nm) following both cadmium loading of native rat liver, Cd,Zn-metallothionein and the metallation of metal-free metallothionein with cadmium. There are two contributions to this effect in Cd,Zn-metallothionein: (i) there is a S leads to Zn band underlying the S leads to Cd band; and (ii) the occupation of zinc sites by cadmium changes the energy of the S leads to Cd transition.     

Molecular and allergenic characterization of recombinant tropomyosin from mud crab Scylla olivacea

Molecular Biology Reports - Tropomyosin is a major allergen in crustaceans, including mud crab species, but its molecular and allergenic properties in Scylla olivacea are not well known. Thus, this...     

拟穴青蟹线粒体COI基因序列克隆及SNPs位点分析

根据拟穴青蟹(Scylla paramamosain)线粒体全序列设计引物,采用PCR产物双向测序法,克隆了线粒体细胞色素C氧化酶亚基Ⅰ(COI)基因部分序列(761 bp),并筛选、分析了拟穴青蟹的SNPs位点.共分析了采自福建省宁德市的16只拟穴青蟹,另外,从GenBank数据库中下载了31条前人提交的拟穴青蟹COI基因序列(长度在425-522 bp之间).利用MEGA 4.0软件对所有序列进行比对分析,结果表明碱基T、C、A和G的平均含量分别为37.6％、17.8％、28.9％和15.7％,G+C的含量平均为33.5％.分析结果表明,在所克隆的761bp的COI基因序列中共发现29个SNPs位点,其出现频率为3.8％.在这29个SNPs位点中,13个为C/T转换(占44.8％),12个为A/G转换(占41.4％),2个为A/T颠换(占6.90％),1个为G/C颠换(占3.45％),另有一个位点(201 bp处)发生了A/C颠换和C/T转换两种类型的碱基替换.氨基酸分析表明,在29个SNPs位点中,有9个位点属于非同义突变,引起了氨基酸的变化;其他20个位点属于同义突变,未引起氨基酸的变化.这将为拟穴青蟹遗传背景和群体遗传多样性研究提供新的分子标记.     

锯缘青蟹(Scylla serrata)Hsp70基因cDNA的克隆及序列分析

采用RT-PCR及RACE技术克隆锯缘青蟹(Scylla serrata)的热休克蛋白Hsp70基因并进行序列分析。克隆测序后拼接得到一条长2482 bp的cDNA序列,该序列ORF(Open reading frame,开放阅读框)为1950 bp,编码649个氨基酸,分子量约为71.06 kD,理论等电点为5.24。3'UTR(untranslated region,非编码区)为158 bp,5'UTR为40 bp。通过antheprot分析发现2个Hsp70家族的签名序列:IFDLGGGTFDVSIL,IVLVGGSTRIPKIQK;Dnak特征基序DLGTT-S-V;非细胞器基序:RARFEEL;核定位信号标签:KKDPSESKRALRRL;胞质Hsp70特征基序EEVD。同源性分析表明,锯缘青蟹Hsp70编码区核苷酸序列与凡纳滨对虾(Litopenaeus vannamei)、斑节对虾(Penaeus monodon)、罗氏沼虾(Macrobrachium rosenbergii)的相似性分别为84.02%、83.87%和79.60%;核苷酸序列所推导出的Hsp70氨基酸序列,与凡纳滨对虾、斑节对虾和罗氏沼虾的相似性分别为92.79%、92.17%和96.47%。本研究克隆了锯缘青蟹Hsp70基因,为进一步深入研究锯缘青蟹的抗逆机理及其遗传改良奠定了基础。