Mating behavior of the squid Loligo opalescens

In the laboratory, the squid Loligo opalescens exhibits dominance behavior during spawning. A single dominant male keeps other male squid from coming near the egg mass he is guarding. Females are allowed to approach the egg mass. The dominant squid uses postural and color displays directed toward challenging males. Similar dominance behavior and displays have not been observed in natural spawns in the ocean.     

Highly Variable Microsatellites in the California Market Squid Loligo opalescens

Attempts to study the genetic population structure of cephalopods are impeded by the low levels of genetic variation in these species. We have developed polymerase chain reaction (PCR) primers for six hypervariable microsatellite markers in order to analyze the molecular population structure in the Californian market squid Loligo opalescens. Each of these genomic loci has been cloned and fully sequenced. Here we report the sequence and properties of the six PCR primer sets for the amplification of hypervariable microsatellites. Heterozygosity levels in six squid samples from different locations are high for all loci tested. Received February 17, 1999; Accepted March 10, 1999     

Molecular cloning and expression of a full-length cDNA encoding acetylcholinesterase in optic lobes of the squid Loligo opalescens: a new member of the cholinesterase family resistant to diisopropyl fluorophosphate

Acetylcholinesterase cDNA was cloned by screening a library from Loligo opalescens optic lobes; cDNA sequence analysis revealed an open reading frame coding for a protein of 610 amino acids that showed 20-41% amino acid identity with the acetylcholinesterases studied so far. The characteristic structure of cholinesterase (the choline binding site, the catalytic triad, and six cysteines that form three intrachain disulfide bonds) was conserved in the protein. The heterologous expression of acetylcholinesterase in COS cells gave a recovery of acetylcholinesterase activity 20-fold higher than in controls. The enzyme, partially purified by affinity chromatography, showed molecular and kinetic features indistinguishable from those of acetylcholinesterase expressed in vivo, which displays a high catalytic efficiency. Both enzymes are true acetylcholinesterase corresponding to phosphatidylinositol-anchored G2a dimers of class I, with a marked substrate specificity for acetylthiocholine. The deduced amino acid sequence may explain some particular kinetic characteristics of Loligo acetylcholinesterase, because the presence of a polar amino acid residue (S313) instead of a nonpolar one [F(288) in Torpedo] in the acyl pocket of the active site could justify the high substrate specificity of the enzyme, the absence of hydrolysis with butyrylthiocholine, and the poor inhibition by the organophosphate diisopropyl fluorophosphate.     

FaRP cell distribution in the developing CNS suggests the involvement of FaRPs in all parts of the chromatophore control pathway in Sepia officinalis (Cephalopoda)

The FMRFamide-related peptide (FaRP) family includes a wide range of neuropeptides that have a role in many biological functions. In cephalopods, these peptides intervene in the peculiar body patterning system used for communication and camouflage. This system is particularly well developed in the cuttlefish and is functional immediately after hatching (stage 30). In this study, we investigate when and how the neural structures involved in the control of body patterning emerge and combine during Sepia embryogenesis, by studying the expression or the production of FaRPs. We detected FaRP expression and production in the nervous system of embryos from the beginning of organogenesis (stage 16). The wider FaRP expression was observed concomitantly with brain differentiation (around stage 22). Until hatching, FaRP-positive cells were located in specific areas of the central and peripheral nervous system (CNS and PNS). Most of these areas were implicated in the control of body patterns, suggesting that FaRPs are involved in all parts of the neural body pattern control system, from the ‘receptive areas’ via the CNS to the chromatophore effectors.     

Skin color variation in eastern Nepal

The purpose of this paper is to provide skin color data on several endogamous groups of eastern Nepal and to demonstrate genetic microdifferentiation in skin color. Skin reflectance measures were taken at the upper inner arm and forehead sites, using the British DSL Model 99 Reflectance Spectrophotometer fitted with blue, green, and red filters. Measurements on 484 males representing six endogamous groups (Jirel, Sunwar, Sherpa, Tamang, Brahman, Chetri) were utilized. After adjusting for group-specific age effects, multivariate likelihood ratio permutation tests were used to assess ethnic differences in skin reflectance means and covariance matrices. Ethnic group membership had a highly significant effect on skin color at the upper inner arm site and at the forehead site. Differential tanning responses among groups were also detected and may represent the influence of genotype-environment interaction on reflectance traits. Mahalanobis distance analysis revealed patterns of microdifferentiation that are inconsistent with oral historical accounts. Little support was found for the ethnohistorical belief that Jirels are a hybrid group descended from Sunwars and Sherpas, even though this scenario is supported by linguistic, anthropometric, and dermatoglyphic data. We suggest that while reflectometric studies of skin pigmentation may be useful in assessing the macrodifferentiation of human populations, the use of skin color in differentiation studies at the local population level needs to be carefully evaluated.     

Ultrastructural changes in the dermal chromatophore unit of Hyla arborea during color change

Summary The structural changes in the chromatophores of Hyla arborea related to changes in skin color were studied by electron microscopy and reflectance microspectrophotometry. During a change from a light to a darker green color, the melanosomes of the melanophores disperse and finally surround the iridophores and partly the xanthophores. The iridophores change from cup-shape to a cylindrical or conical shape with a simultaneous change in the orientation of the platelets from being parallel to the upper surface of the iridophores to being more irregular. The xanthophores change from lens-shape to plate-shape. The color change from green to grey seems always to go through a transitional black-green or dark olive green to dark grey. During this change the xanthophores migrate down between the iridophores, and in grey skins they are sometimes found beneath them. The pterinosomes gather in the periphery of the cell, while the carotenoid vesicles aggregate around the nucleus. The iridophores in grey skin are almost ball-shaped with concentric layers of platelets. A lighter grey color arises from a darker grey by an aggregation of melanosomes. The chromatophore values previously defined for Hyla cinerea are applicable in Hyla arborea, and the ultrastructural studies support the assumptions previously made to explain these values.The author wishes to thank Drs. P. Budtz, J. Dyck and L.O. Larsen for valuable discussions and J. Dyck for kindly providing the spectrophotometer granted him by the Danish National Science Foundation. The skilled technical assistance of Mrs. E. Schiøtt Hansen is gratefully acknowledged. Permission was granted by the Springer-Verlag to republish the illustrations of W.J. Schmidt (1920)     

Morphology and electrical properties of Schwann cells around the giant axon of the squids Loligo forbesi and Loligo vulgaris.

The first successful dye-fills of Schwann cells around the split giant axon of Loligo show them to be spindle-shaped cells ca. 600 microns long and 20 microns wide lying parallel to the axonal axis. There are some 50,000 Schwann cells per cm2 of axonal membrane. Only a small part (ca. 6% of each Schwann cell membrane) is in contact with the periaxonal space, the remainder is overlain by adjacent Schwann cells, or applied to the basal lamina. The mean membrane potential of the Schwann cells in artificial seawater (ASW) varies from around -40 mV in fresh split-axon preparations to around -60 to -70 mV after 1-2 h; this hyperpolarization is not seen in preparations dissected and maintained in Ca2(+)-free ASW. Electrical- and dye-coupling (abolished by prior octanol treatment) is present between Schwann cells, but is weaker in cells with lower (less negative) membrane potentials. The implications for potassium homeostasis around the axon are briefly discussed.     

The distribution of nucleic acids in the giant axon of the squid (Loligo pealii)

Abstract— RNA and DNA were determined in the axoplasm and sheath of squid giant axons. If the RNA was related to axonal length, equivalent amounts of RNA were found in the axoplasm and sheath. However, when it was expressed as a function of dry wt. or residue protein, the concentration of RNA in the sheath was four times greater than in the axoplasm. A ratio of 1·1 was found for sheath RNA/sheath DNA. Less DNA was present in the axoplasm than the amount which could be accurately determined with the methods employed.     

A note on the ultrastructure of the Octopus olfactory organ

Summary The fine structure of the so-called olfactory organ of Octopus vulgaris has been investigated. Electron microscopy shows the superficial layer of the epithelium to consist mainly of cells bearing microvilli. Below this, often very deeply, lie very many large cells, which bear numerous cilia. These cells open to the surface via narrow processes running between the epithelial cells. Although details of their innervation have yet to be established the large cells are assumed to be receptors and these findings are interpreted as evidence that this organ is indeed chemosensory.We would like to thank the staff of the Stazione Zoologica di Napoli for their help and excellent facilities; and the S.R.C. for financial support (a studentship to P.L.W. and grant B/SR/5287 to J.B.M.)     

Binding sites for [3H]-acetylcholine and 125I-alpha-bungarotoxin in the optic ganglion of Loligo pealii

1. In the optic ganglion of Loligo pealii, binding sites for [3H]-acetylcholine (KD: 5.2 x 10(-7) M; Bmax: 1.7 x 10(-11) mol/g tissue) and 125I-alpha-bungarotoxin (KD: 3.3 x 10(-9) M; Bmax: 9.7 x 10(-11) mol/g tissue) were observed. 2. Both sites are blocked by nicotinic compounds, but differ significantly in their affinity for individual ligands, with the acetylcholine site preferentially binding agonists, and the toxin site, antagonists. 3.The acetylcholine site is substantially more thermolabile than the toxin site. 4. A partial separation of the two binding activities is accomplished by sucrose density centrifugation. 5. These observations and a comparison with other tissues (Torpedo californica electroplaque; chick optic lobe; rat brain) suggest the presence, in the squid, of more than one kind of neuronal nicotinic receptor.     

松江鲈鱼皮肤的显微和亚显微结构

采用光学显微镜、扫描电镜和透射电镜,对松江鲈鱼(Trachidermus fasciatus)成体皮肤的显微和亚显微结构进行了观察。结果表明,松江鲈鱼体表不同部位皮肤的厚薄不一,但基本结构相似。皮肤由表皮和真皮层构成。松江鲈鱼的皮肤裸露无鳞,表皮层较薄,由约4～8层细胞构成,主要由复层上皮细胞和黏液细胞及基底细胞组成。表层细胞呈扁平、多边形,细胞之间主要靠桥粒紧密连接,连接处形成增厚的边缘嵴状突起。表皮细胞游离面向内凹陷,表面形成指纹状微嵴。黏液细胞呈圆形或卵圆形,散布在上皮细胞之间。黏液细胞内的黏原颗粒具有椭圆颗粒状、均匀致密的块状和疏松丝状3种不同形态。真皮通过基膜与表皮相连,由稀疏层和致密层构成。真皮结缔组织在腹部较厚而在其他部位较薄。表皮与真皮连接处有色素层,头部、背部、尾柄和体侧皮肤色素细胞分布多,色素层明显,而腹部和颏部皮肤缺少色素。松江鲈鱼黄河群体真皮层中有角质棘状突起,而滦河群体则无。头部、体侧和尾柄处皮肤上还分布有侧线孔和表面神经丘等感觉器官。     

Microsatellites reveal high levels of gene flow among populations of the California squid Loligo opalescens

Information on the extent of genetic differentiation among populations of the squid Loligo opalescens is crucial for the conservation of this commercially utilized species. We analysed six highly variable microsatellite loci in 11 collections of L. opalescens from different locations and spawning seasons to estimate the relative influence of two major evolutionary forces, gene flow and genetic drift. Microsatellite allele frequency patterns suggest that gene flow prevents population differentiation in L. opalescens. Tests for genetic differentiation showed homogeneity of the samples with an overall FST/RST of 0.0028/-0.0013. Genetic uniformity among samples from different year classes indicates that allele frequency patterns in L. opalescens are relatively stable over time. However, a more complete and detailed picture of fine-scale allele frequency shifts in this species will require a systematic microsatellite analysis of local populations over consecutive spawning cycles.     

The branchial gland: A site of haemocyanin synthesis in Octopus

Summary The paired branchial glands in cephalopods are essential for life. The electron microscope reveals them to consist of cells containing masses of endoplasmic reticulum organised in parallel arrays together with pale areas between the reticulum that contain vacuoles. All three regions of the cells contain masses of haemocyanin particles and it is suggested that the gland is the site of haemocyanin synthesis, the particles being made amongst the endoplasmic reticulum at discharged into the pale areas and vacuoles before being released into the general circulation.It is a pleasure to thank the Director and Staff of the Stazione Zoologica of Naples, and the Marine Biological Association Laboratory, Plymouth for their excellent facilities so freely provided. Much of the material was collected at Naples where one of us (JBM) was generously supported by the S.R.C. We thank many colleagues, too numerous to mention individually, who helped in different ways and we are grateful, too, for encouragement, support, and discussion, to Professors I. Chester Jones and J. Z. Young.     

Melanophore death and disappearance produces color metamorphosis in the polychromatic Midas cichlid (Cichlasoma citrinellum)

Summary We describe the histological basis of color metamorphosis in the polychromatic Midas cichlid, Cichlasoma citrinellum. Eight percent of the individuals in a natural population transform from gray with black markings to orange, simultaneously losing their ability to adjust coloration in response to background and social context. This trait is inherited. Light- and electron microscopy revealed that this transformation is a two-step process. First, the melanophores die, then macrophage-like cells remove the debris. As a result of this initial process, the underlying xanthophores become visible, producing the orange coloration. A similar process may occur in individuals that further transform to white, or go directly from gray to white.     

The influence of hypoxia on the thermal sensitivity of skin colouration in the bearded dragon, Pogona vitticeps

One physiological mechanism used by reptiles to remain within thermal optima is their ability to reversibly alter skin colour, imparting changes in overall reflectance, and influencing the rate of heat gain from incident radiation. The ability to lighten or darken their skin is caused by the movement of pigment within the dermal chromatophore cells. Additionally, lizards, as ectotherms, significantly lower their preferred body temperatures when experiencing stressors such as hypoxia. This decrease in preferred temperature has been proposed to be the result of a downward adjustment of the thermal set-point, the temperature around which the body temperature is typically defended. We tested the hypothesis that lightening of the skin in lizards would be modified by hypoxia in a manner consistent with the known reduction in preferred temperatures. Skin colouration values of the dorsal skin of bearded dragons were analysed at three different levels of oxygen (20.8, 9.9 and 4.9 kPa) and at temperatures spanning the preferred temperature range (30, 32, 34, 36, 38 and 40 C). Hypoxic lizards lightened their skin at lower ambient temperatures more than normoxic ones, and in an oxygen-dependent fashion. The orchestrated adjustment of skin reflectance suggests that this physiological trait is being regulated at a new and lower set-point. Evidence from this study demonstrates that skin colouration plays a role in body temperature regulation and that the reduction in temperature set-point so prevalent in hypoxia is also manifested in this physiological trait.     

Electron-microscopic observations of the gravity receptor epithelia of normal and spinner juvenile Octopus maya

Summary Light and electron microscopy of the gravity receptor epithelia (maculae) of statocysts of normal and spinner juvenile Octopus maya showed differences between the structures of the hair cells, supporting cells, and afferent neurons of these cephalopods. The maculae of spinner animals were approximately 30% smaller in their surface area and had 40% fewer hair cells. Moreover, the average distance between randomly-chosen hair bundles in scanning electron micrographs of maculae of normal animals was significantly greater (4.33±6.47 m) than those of maculae of spinner animals (3.38±4.90 m; P<0.0001). The sectional area of the supporting cell's microvilli in spinners maculae was larger (0.16±0.18 m) than those of normal (0.10±0.10 m; P<0.0001) O. maya. The morphological differences observed between certain structural components of the maculae of normal and spinner O. maya may be related to the absence and/or malformation of the neuroepithelial suprastructures in spinners. This may have direct or indirect effects related to their inability to orient to gravity with these organs.     

负压封闭引流技术与传统打包技术治疗四肢软组织损伤及后期植皮的临床疗效比较

目的:观察和比较负压引流技术(vacuum sealing drainage,VSD)与传统打包技术治疗四肢软组织损伤及后期植皮的临床疗效。方法:选择2010年1月-2013年1月在我院分别接受负压引流技术(实验组)及常规打包技术(对照组)治疗的随访资料完整的四肢软组织损伤患者共127例。记录和比较两组患者的手术时间、住院时间、创面愈合时间、换药次数和并发症的发生情况等。结果:实验组的手术时间、住院时间、创面愈合时间、平均手术次数和换药次数均明显短于或少于对照组(P0.05)。两组术后创面感染的发生情况比较无统计学差异,经再次清创后感染控制,行植皮手术后恢复良好。结论:与传统的打包技术比较,VSD技术用于治疗软组织损伤及后期植皮,可以更有效地缩短手术和住院时间及减少手术次数,是一种治疗四肢软组织损伤的安全有效的方法。     

Skin color comparisons among ethnic groups of college men

Reflectance readings of skin color were taken on the medial aspect of the left upper arm. The subjects were United States college men between ages 18 and 27 years attending the University of South Carolina. Using the DSL 99 Reflectance Spectrophotometer, readings were obtained under controlled conditions at five settings (601, 603, 605, 607, 609). Ethnic groups studied included young men of 1) Northwest European White ancestry, 2) West African Black ancestry, and 3) Afro-Black/Amerind ancestry. Means and variability statistics serve to describe the skin color distributions. Means were near 12 and 32 for filters 601 and 609 on men of West African Black ancestry, with corresponding means near 36 and 64 on men of Northwest European White ancestry. There was no overlapping of comparable frequency distributions from these two ethnic groups. Significance tests at P = .01 allowed acceptance of the hypothesis that skin color on the medial arm surface was darker for young men of Afro-Black ancestry than for those of 75% Afro-Black ancestry and 25% Amerind ancestry. Means from original data were compared with means from earlier studies on black and white males in Africa, America, and Europe.