Morphological changes in development of pharyngeal teeth inMylopharyngodon piceus

Adult pharyngeal teeth inMylopharyngodon piceus are molariform. Based on SEM observations of the developing teeth, this paper describes the morphological diversification of pharyngeal teeth inM. piceus. The larval and juvenile teeth are changed from conical to adult molariform teeth through seven stages. Comparisons are made between each stage and corresponding types in some species of different subfamilies in Cyprinidae. It is considered that the ontogenetic resemblances of the pharyngeal teeth bear relationship to the phylogeny of cyprinids. This project was funded by the International Cooperation of Japan—China and the National Natural Science Foundation of China     

APPEARANCE PATTERN OF TOOTH GERMS WITH DEVELOPMENTAL PROCESS IN MYLOPHARYNGODON PICEUS

The pharyngeal dental formula of Mylopharyngodon piceus is 4-5 as a rule, and the dentition isasymmetrical. It is difficult to identify each tooth in the larval dentition. In this paper the appearancepattem of tooth germ with developmental process in this fish is described in detail. The formationpattern of the left dentition is contrasted with that of the right one. In the developmental process,the left pharyngeal dentition lacks teeth at position An3. Thus the left dentition is D-type as designatedby Nakajima(1984), while the right one is A-type.     

Appearance pattern of tooth germs with developmental process inMylopharyngodon piceus

The pharyngeal dental formula ofMylopharyngodon piceus is 4–5 as a rule, and the dentition is asymmetrical. It is difficult to identify each tooth in the larval dentition. In this paper the appearance pattern of tooth germ with development process in this fish is described in detail. The formation pattern of the left dentition is contrasted with that of the right one. In the developmental process, the left pharyngeal dentition lacks teeth at position An3. Thus the left dentition is D-type as designated by Nakajima (1984), while the right one is A-type. This project was funded by the International Cooperation of Japan-China and the National Natural Science Foundation of China.     

An integrative study of larval organogenesis of American shad <Emphasis Type="Italic">Alosa sapidissima</Emphasis> in histological aspects

We describe organogenesis at a histological level in American shad (Alosa sapidissima) larvae from 0 until 45 days after hatching (DAH). Larval development was divided into four stages based on the feeding mode, external morphological features, and structural changes in the organs: stage 1 (0–2 DAH), stage 2 (3–5 DAH), stage 3 (6–26 DAH) and stage 4 (27–45 DAH). At early stage 2 (3 DAH), American shad larvae developed the initial digestive and absorptive tissues, including the mouth and anal opening, buccopharyngeal cavity, oesophagus, incipient stomach, anterior and posterior intestine, differentiated hepatocytes, and exocrine pancreas. The digestive and absorptive capacity developed further in stages 2 to 3, at which time the pharyngeal teeth, taste buds, gut mucosa folds, differentiated stomach, and gastric glands could be observed. Four defined compartments were discernible in the heart at 4 DAH. From 3 to 13 DAH, the excretory systems started to develop, accompanied by urinary bladder opening, the appearance and development of primordial pronephros, and the proliferation and convolution of renal tubules. Primordial gills were detected at 2 DAH, the pseudobranch was visible at 6 DAH, and the filaments and lamellae proliferated rapidly during stage 3. The primordial swim bladder was first observed at 2 DAH and started to inflate at 9 DAH; from then on, it expanded constantly. The spleen was first observed at 8 DAH and the thymus was evident at 12 DAH. From stage 4 onwards, most organs essentially manifested an increase in size, number, and complexity of tissue structure.     

A NEW SPECIES OF RANINOIDES (CRUSTACEA: DECAPODA: RANINIDAE) FROM OFF THE SOUTHEASTERN COAST OF HAINAN ISLAND AND NANSHA ISLANDS

ＩＮＴＲＯＤＵＣＴＩＯＮＲａｎｉｎｏｉｄｅｓｆｏｕｎｄｂｙＨ .ＭｉｌｎｅＥｄｗａｒｄｓ,1 83 7,ｎｏｗｉｎｃｌｕｄｅｓｓｉｘｓｐｅｃｉｅｓｉｎＩｎｄｏ ＰａｃｉｆｉｃＯｃｅａｎｓ:Ｒ .ｐｅｒｓｏｎａｔｕｓＨｅｎｄｅｒｓｏｎ ,1 888,Ｒ .ｓｅｒａｔｉｆｒｏｎｓＨｅｎｄｅｒｓｏｎ,1 888,Ｒ .ｈｅｎｄｅｒｓｏｎｉＣｈｏｐｒａ,1 93 1 ,Ｒ .ｂａｒｎａｒｄｉｉＳａｋａｉ,1 974 ,Ｒ .ｃｒｏｓｎｉｅｒｉＲｉｂｅｓ,1 989ａｎｄＲ .ｉｎｔｅｒｍｅｄｉｕｓＤａｉｅｔＸｕ,1 993 .ＲｅｃｅｎｔｌｙｒｅｐｏｒｔｅｄＲ .ｐｅｒｓｏ…     

A new pterosaur (Pterosauria) from Middle Jurassic Tiaojishan Formation of western Liaoning,China

A new pterosaur Archaeoistiodactylus linglongtaensis gen.et sp.nov.is erected based on an incomplete skeleton with a partial skull and lower jaw.The new taxon is characterized by circular tooth sockets of anterior mandibular teeth,the anterior teeth of the upper jaw bearing posteriorly directed crowns,a relatively short metacarpus,and wing phalanges 2 and 3 and the tibia subequal in length.It possesses some plesiomorphic characters such as short metacarpals and circular tooth sockets.The pointed jaw tip present in the new taxon indicates that the expanded jaw tips of later istiodactylids are a derived character state,and the new taxon represents the first istiodactylus-like pterosaur found from the pre-Late Jurassic deposits,which provides a key role in our understanding the origin and evolution of the known istiodactylid pterosaurs.Archaeoistiodactylus is regarded as the ancestor form of the known istiodactylid pterosaur.     

Design principle for parameters and interferences of tungsten carbide insert interface on roller bits

The lifetime of roll-bits with inserted tooth will be obviously decreased while drilling in strata and the tungsten carbide can be integrally separated from the roll-cone,which will need more trip out time to replace the roller bit.This study provides an entire analysis on stress as well as strength for teeth and tooth holes in loaded conditions.Qualities of tooth drop from matrix within roller bit.The optimized interferences of teeth inserted into the bit can be reasonably obtained by the critical interference derived from some relevant influence factors on the tooth-fixing quality of roller bits.     

A new pterosaur (Pterosauria) from Middle Jurassic Tiaojishan Formation of western Liaoning,China

A new pterosaur Archaeoistiodactylus linglongtaensis gen. et sp. nov. is erected based on an incomplete skeleton with a partial skull and lower jaw. The new taxon is characterized by circular tooth sockets of anterior mandibular teeth,the anterior teeth of the upper jaw bearing posteriorly directed crowns,a relatively short metacarpus,and wing phalanges 2 and 3 and the tibia subequal in length. It possesses some plesiomorphic characters such as short metacarpals and circular tooth sockets. The pointed jaw tip present in the new taxon indicates that the expanded jaw tips of later istiodactylids are a derived character state,and the new taxon represents the first istiodactylus-like pterosaur found from the pre-Late Jurassic deposits,which provides a key role in our understanding the origin and evolution of the known istiodactylid pterosaurs. Archaeoistiodactylus is regarded as the ancestor form of the known istiodactylid pterosaur.     

A NEW SPECIES OF RANINOIDES （CRUSTACEA ： DECAPODA ： RANINIDAE） FROM OFF THE SOUTHEASTERN COAST OF HAINAN ISLAND AND NANSHA ISLANDS

Ranlnoides longifions new species, off SE coast of Hainan Island, dorsal surface of carapace with an arched granular edge across carapace between the anterolateral teeth, median frontal tooth longest, second frontal teeth subquadrate.     

A new genus and species of shrimp(Crustacea:Axiidea:Axiidae) from the Caroline Ridge,Northwest Pacific

A new genus and species of axiid shrimp,Carolinaxius kexuae gen.et sp.nov.is described and illustrated based on a single specimen collected from an unnamed seamount in the Caroline Ridge,Northwest Pacific.Although both chelipeds are mis sing,the specimen can be distinguished from other axiid genera by a combination of characteristics:narrowly triangular ro strum;median carina and lateral gastric carina each with one prominent tooth;submedian gastric carinae converging po steriorly,with teeth;cornea weakly pigmented,eyestalk with acute distome sial tooth on dorsal surface;male pleopod 1 two-articled;pleopod 2 with appendix interna and appendix masculina;pleopods 3-5 with appendix interna.The molecular phylogeny suggests the new genus is most closely related to another recently described genus living inside hexactinellid sponges on seamounts in the Indian Ocean,Montanaxius Dworschak,2016.However,it differs from Montanaxius in the shape of the rostrum,the arrangement of teeth on the carapace,and the shape of the eyestalk.Besides,the significant molecular differences support the two belonging to different genera.     

军曹鱼骨骼系统的研究

对军曹鱼骨骼系统进行了系统研究。结果表明军曹鱼有发达的额骨、鼻骨和上耳骨,犁 骨、腭骨具齿,左右顶骨被上枕骨分开,具背肋和腹肋,无眶蝶骨,头部有些骨骼左右不对称。     

基于单齿侵入理论的牙轮钻头钻速方程

考虑井底水平地应力、钻井流体压力及地层孔隙压力,基于单齿侵入理论推导单齿侵入井底岩石的侵深公式,建立纯滚动锥形齿、楔形齿和滚动、剪切复合运动锥形齿等牙轮钻头的钻速方程.通过实验分析刃尖角、井底液柱压力对单齿侵入深度的影响,以及转速、轴向载荷对微钻头、牙轮钻头机械钻速的影响.结果表明:随着牙齿刃尖角的增大,锥形齿和楔形齿的侵深呈指数递减趋势;随着井底液柱压力的增大,牙齿侵入深度呈指数递减趋势,其中锥形齿降低速率大.在软到中硬地层中,牙齿侵入深度大,冲击侵入、回转剪切复合破岩方式的破岩效率高;在硬度地层中,牙齿侵入深度小,纯滚动冲击侵入破岩效率高.为分析实钻时牙轮钻头的机械钻速提供计算方法.     

On paleoecology of carnivorous dinosaurs(Tyrannosauridae,Dromaeosauridae) from Late Cretaceous fossil deposits of Amur region,Russian Far East

Present article is on Russian Far East carnivorous dinosaur paleoecology.Described summary is based on detailed study and comparison of isolated shed teeth morphology.     

On paleoecology of carnivorous dinosaurs ( Tyrannosauridae，Dromaeosauridae) from Late Cretaceous fossil deposits of Amur region，Russian Far East

Present article is on Russian Far East carnivorous dinosaur paleoecology． Described summary is based on detailed study and comparison of isolated shed teeth morphology．     

Paramonohystera weihaiensis sp.nov.(Xyalidae,Nematoda) from the intertidal beach of the Yellow Sea,China

A new species of free-living marine nematode of the genus Paramonohystera was described from the intertidal beach,Weihai.Paramonohystera weihaiensis sp.nov.is characterized by cervical region with a circle of long setae;tail sexual dimorphism,male tail angled dorsally with sharp narrowed of the body at the cloaca,female tail ordinary conico-cylindrical; spicules slender,2.5 abd long; gubemaculum plate,enlarged distal end with two teeth,without apophysis; precloacal supplements absent;Four caudal gland cells obviously extended to tail.The new species differs from the other fourteen known valid congeners by the combination of its characteristics:a circle of long cervical setae,tail sexual dimorphism,spicules slender,2.5 abd long,gubernaculum plate with a distal pair of teeth.     

A new free-living marine nematode species of Rhinema from the South China Sea

A new free-living marine nematode species of the genus Rhinema belonging to the family Monoposthiidae was collected from marine sediments in the Qiongzhou Strait of the South China Sea,and it is described here as Rhinema longispicula sp.nov.The new species is characterized by coarsely annulated cuticle with 12 longitudinal ridges(alae) marked as reversed V-shaped.The first and second annuli broader and form a kind of a cephalic capsule.The amphideal fovea circular,situated in the middle of the broad second annulus,not surrounded by dense annulations.Buccal cavity cylindrical with a large dorsal tooth.Pharynx with a prominent anterior pharyngeal bulb and an elongated terminal bulb.Elongate spicules strongly curved,with cephalated proximal end and pointed distal end.Gubernaculum boat-shaped,without apophysis.A long and blunt precloacal seta present.Female with two opposed,outstretched ovaries.     

Pyropia haitanensis polysaccharide extends lifespan by inhibiting protein aggregation in Caenorhabditis elegans

Pyropia haitanensis poly saccharide(LP) have been found for having many excellent functions such as anti-aging.Using Caenorhabditis elegans models,we evaluated the anti-aging activity of LP by observing the lifespan,reproduction,pharyngeal pumping,stress response,quantitative fluorescence of poly glutamic acid,and nuclear localization of DAP-16 of worms.The results reveal that LP could extend the adult lifespan of wild-type and polyQ nematodes,indicating a connection of its anti-aging benefit with the toxicity-suppressing effect The number of polyglutamic acid aggregates in high concentration groups decreased by 24.39%(P0.05) to the control.The high-dose group strongly induced DAP-16 nuclear translocation over intermediate and cytosolic localizations compared with the control(P0.001).Therefore,we believe that LP could extend the lifespan and reduce the protein aggregation in C.elegans through nuclear DAF-16::GFP expression.     

干旱区树轮年代学研究中的交叉定年技术

交叉定年技术是树轮年代学的基础 ,定年的准确性直接关系到进一步研究的可靠性。而不同气候区的树轮年代学研究具有不同的特点 ,干旱地区树轮宽度序列的平均敏感度高、缺轮率高 ,给交叉定年工作带来了一定困难。笔者结合实际工作取得的数据和大量文献详细地介绍了干旱区树轮年代学研究的特点及一些特有的研究技术 ,并对交叉定年的方法、伪轮的判定、样品量的确定等一些关键问题进行了进一步的讨论 ,为以后的工作提供参考。     

Ontogeny of the immune system in rock bream Oplegnathus fasciatus

Histogenesis of the immune system and specific activity of superoxide dismutase(SOD) were studied in rock bream Oplegnathus fasciatus from fertilization to 50 days after hatching(DAH).The pronephric tubule primordium developed in the embryo,14 h 30 min post fertilization.The spleen anlage was observed between the swim bladder and the intestine at 5 DAH,and the thymus was formed as a paired structure under the pharyngeal epithelium above the gill arch at 10 DAH.The order of the immune organs becoming lymphoid was the pronephric kidney(10 DAH),thymus(15 DAH) and spleen(21 DAH).As the embryo developed,the specific activity of SOD gradually increased until hatching,but subsequently SOD activity continuously decreased to a minimum at 14 DAH.After the spleen became lymphoid,the specific activity of SOD was relatively stable.It is suggested that the immaturity of the lymphoid organs and low specific activity of SOD was the cause of the high mortality of fingerlings 12 to 16 DAH.