Epidemiological characteristics and related factors of crayfish associated rhabdomyolysis syndrome in Baiyun District, Guangzhou / 公共卫生与预防医学

Objective To investigate the clinical and epidemiological characteristics of crayfish associated rhabdomyolysis syndrome in Baiyun District, Guangzhou, and explore the related factors, and to provide evidence for the prevention of crayfish rhabdomyolysis syndrome. Methods The cases of crawfish associated rhabdomyolysis syndrome were found through the foodborne disease surveillance and reporting system, and a field epidemiological investigation was carried out to analyze the clinical and epidemiological characteristics of the cases. Results A total of 25 cases of crayfish associated rhabdomyolysis syndrome occurred in 2020. The intake of crayfish of the cases ranged from 5 to 25, the incubation period was 1 to 9.5h, and the interval from onset to medical treatment was 0.17 to 9h. All the cases had muscle pain, and the content of creatine kinase (CK) in the cases increased to varying degrees (128-17851 U/L). Retrospective cohort analysis of 10 crayfish events found no correlation between the consumption of different parts of crayfish and the incidence of crayfish-related rhabdomyolysis syndrome. Conclusion The incidence of rhabdomyolysis syndrome reported in Baiyun District of Guangzhou is related to the consumption of crayfish, but the pathogenic factors need to be further studied. It is suggested to strengthen the supervision of crayfish breeding, transportation, sales, and processing to ensure the health of consumers.

Áreas en riesgo de invasión por Procambarus clarkii (Decapoda: Cambaridae) un cangrejo de río introducido en Colombia / Areas at risk of invasion by Procambarus clarkii (Decapoda: Cambaridae) a crayfish introduced in Colombia

Introducción: El proceso de invasión biológica es una de las mayores amenazas a la biodiversidad y ecosistemas, con actuales y potenciales impactos en la salud pública y conservación. Procambarus clarkii es un crustáceo decápodo, originario del sur de Estados Unidos y noreste de México, que puede adaptarse a diferentes condiciones ambientales debido a su plasticidad ecológica. Objetivo: Se caracterizó el nicho ecológico fundamental existente de Procambarus clarkii con el fin de predecir las áreas con idoneidad ambiental para el potencial establecimiento de la especie en Suramérica y Colombia. Métodos: Usamos modelos de nichos ecológicos calibrados en el área nativa, elaborados con el algoritmo Maxent, basados en datos de presencia extraídos de GBIF y variables hidroclimáticas de ecosistemas acuáticos a una resolución de 1 km2. Resultados: En Suramérica el modelo indicó un potencial geográfico amplio de invasión mostrando áreas ambientalmente idóneas para la presencia y expansión hacia Colombia, Venezuela, Perú, Ecuador, Brasil, Guyana, Surinam, Bolivia, Uruguay, Argentina, Paraguay y Chile. En Colombia, el modelo predijo que las áreas idóneas se ubican principalmente en el norte y oriente, incluidos diversos ecosistemas, como: bosques tropicales, bosques basales, bosques riparios y sabanas. La especie tiene una alta posibilidad de expandirse hacia áreas de distribución de latitudes bajas, ocupando zonas hacia la parte norte de la región Caribe colombiana, en departamentos de Magdalena, Cesar, Córdoba y Atlántico. También se predijo áreas con idoneidad ambiental en el oriente de Colombia, hacia la extensión de la planicie oriental de la Orinoquia, una región de baja altitud en: Arauca, Casanare, Meta y Vichada. Conclusión: En este estudio se aplican modelos de nichos ecológicos, que puede ser de interés en la planeación de estrategias o la creación de planes de manejo, como sistemas de alerta temprana para evitar el establecimiento de esta especie.

Introduction: Biological invasions are a major threat to biodiversity and ecosystems, with current and potential impacts on public health and conservation. Procambarus clarkii is a decapod crustacean, native to the Southern United States and Northeastern Mexico, which may adapt to different environmental conditions due to its ecological plasticity. Objective: The existing fundamental ecological niche of Procambarus clarkii was characterized in order to predict areas with environmental suitability for the potential establishment of the species in South America and Colombia. Methods: We used models of calibrated ecological niches in the native area, elaborated with the Maxent algorithm, based on occurrence data extracted from GBIF and hydroclimatic variables of aquatic ecosystems at a resolution of 1 km2. Results: The model indicated a wide geographic area for invasion potential in South America, predicting environmentally suitable areas for the presence and expansion towards Colombia, Venezuela, Peru, Ecuador, Brazil, Guyana, Surinam, Bolivia, Uruguay, Argentina, Paraguay and Chile. In Colombia, suitable areas predicted by the model are located mainly in the North and East of the country, spanning a diversity of ecosystems, such as tropical forests, basal forests, riparian forests and savannas. The species has a high possibility of expanding into low latitude distribution areas, occupying areas towards the Northern part of the Colombian Caribbean region, in the departments of Magdalena, Cesar, Cordoba and Atlántico. Suitability areas environmental were also predicted in Eastern Colombia, towards the extension of the Eastern plain of the Orinoquia, a low altitude region in Arauca, Casanare, Meta and Vichada. Conclusion: This study applies ecological niche models, which may be of interest in the planning of strategies or the creation of management plans, such as early warning systems that prevent the establishment of this species.

Analysis of the population structure and genetic diversity of the red swamp crayfish (Procambarus clarkii) in China using SSR markers

BACKGROUND: Procambarus clarkii produces high-quality, delicious meat that is high in protein, low in fat, and rich in calcium and phosphorus. It has become an important aquatic resource in China. Our objectives are (i) to analyze the level of genetic diversity of P. clarkii populations; (ii) to explore the genetic differentiation (Gst); and (iii) to propose appropriate strategies for the conservation. RESULTS: In this study, Shannon's index (I) and Nei's gene diversity index (H) for P. clarkii were high (I = 0.3462 and H = 0.2325 on average and I = 0.6264, H = 0.4377 at the species level) based on the SSR markers. The expected heterozygosity value of 17 microsatellite loci in 25 crayfish populations was 0.9317, the observed heterozygosity value was 0.9121, and the observed number of alleles per locus was 2.000; and the effective number of alleles per locus was 1.8075. Among the P. clarkii populations, the inbreeding coefficient within populations (Fis) was 0.2315, overall inbreeding coefficient (Fit) was 0.4438, genetic differentiation coefficient among populations (Fst) was 0.3145 and gene differentiation (Gst) was 0.4785 based on SSR analyses. The cluster analysis results obtained by unweighted pair-group method with arithmetic mean (UPGMA) analysis, principal coordinate analysis (PCoA) and STRUCTURE analysis were similar. A mantel test showed that the isolation-by-distance pattern was not significant. CONCLUSIONS: The high Gst among P. clarkii populations is attributed to genetic drift and geographic isolation. The results indicated that more P. clarkii populations should be collected when formulating conservation and aquaculture strategies.

Decerebration induced by surgical transection of cerebral ganglion of crayfish

Background: Since the neural structures of the crayfish brain closely resemble their equivalent in the mammals. This can be suggested by observing the similarity that exists in the brain divided by the surgical transection of the crayfish brain in which the protocerebrum remains attached to the first two cranial nerves, findings also described by Frederic Bremer in 1935 in cats with cerebral transection.Methods: Total 11 Adult male crayfish were trained to respond with defense reflex, the animals were placed in water at 0°C, remained without any movement, and subsequently through a small incision of 3 mm in diameter in the medial antero region and dorsal cephalothorax region, a surgical section of the cerebral ganglion was performed. Immediately after surgery, metal microelectrodes were implanted to collect the activity of the photoreceptors and visual fibers.Results: Once the defense reflex begins to recover in previously decerebrated crayfish, it means that it shows signs of reconnection. The isolated protocerebrum with the deutocerebrum olfactory lobe remain alive for several days and the neuronal connections were reestablished, as measured throughout the bilateral defense activity. The defense reflex was observed in all animals and then recovered after surgery.Conclusions: The crayfish is an excellent model to work the visual activity, all coding of visual information was suppressed in de-cerebrated crayfish. The recovery of the neural disconnection is observed from 40 days, where the defence reflex appears again before visual stimuli.

Clinical characteristics of patients with Haff disease after eating crayfish / 世界急诊医学杂志（英文）

BACKGROUND@# The study aimed to explore the clinical presentations, laboratory findings, treatments and prognosis of patients with Haff disease after eating crayfish.@*METHODS@#Sixteen patients with Haff disease after eating crayfish were admitted to the Emergency Department of Beijing Chao-yang Hospital between June 2013 and August 2017. Clinical data was retrospectively analyzed.@*RESULTS@#Alcohol consumption and exercise were found to be most commonly associated with the onset of rhabdomyolysis after consuming crayfish. Most patients were young adults and the symptoms mostly occurred within 24 hours of consumption of crayfish. Clinical symptoms included myalgia (100%), fatigue (87.5%), nausea (43.8%), dizziness (62.5%), chest distress (37.5%) and fever (18.8%). Also found after laboratory testing was elevations in the levels of creatine kinase (11,376±5,535 U/L), myoglobin (350±158 ng/mL), lactate dehydrogenase (6,539±3,180 U/L), alanine transaminase (174±71 U/L) and aspartate aminase (348±100 U/L). The incidence of renal dysfunction was low (6.25%), and all 16 patients had a good prognosis.@*CONCLUSION@#Patients with Haff disease exhibited typical symptoms after consuming crayfish, and laboratory findings gave highly accurate diagnostic results. The development of rhabdomyolysis was considered to be associated with alcohol consumption and exercise, but further studies are needed to demonstrate its relationship with crayfish consumption. Compared with other causes of rhabdomyolysis, rhabdomyolysis after crayfish consumption has fewer complications and better prognosis.

Epidemiological and clinical characteristics of 109 patients with crayfish-related rhabdomyolysis / 中华内科杂志

A total of 109 in patients with crayfish-related rhabdomyolysis were enrolled in our hospital from July to August 2016,including 31.2％(34/109)males and 68.8％ (75/109)females.The number of home-cooked crayfish accounted for 60.6％ (66/109).Main symptom was back pain 96.3％ (105/109).The misdiagnosis rate was 15.6％ (17/109).On day 1,2,3 after admission and the day before discharge,serum creatine kinase were 1 175(446,2 258)IU/L,3 710(2 137,8 875)IU/L,1 899(1 063,4595)IU/L and 317 (152,532)IU/L,respectively(P＜0.001).Serum myoglobin were (603±484)μg/L,(313±284)μg/L,(104±74)μg/L and (55 ± 20)μg/L,respectively(F=39.1,P＜0.001).Females were more susceptible to cra.crayfish-related rhabdomyolysis.Home-cooked crayfish is prone to induce rhabdomyolysis and easily to be misdiagnosed.Creatine kinase and myoglobin showed characteristic dynamic changes.

Recent Incidence of Paragonimus westermani Metacercariae in Freshwater Crayfish, Cambaroides similis, from Two Enzootic Sites in Jeollanam-do, Korea

An epidemiological study was performed to know the recent infection status of Paragonimus westermani metacercariae (PwMc) in freshwater crayfish, Cambaroides similis, from 2 streams in Jeollanam-do, Republic of Korea. Crayfish were collected from creeks in Bogil-do (Island), Wando-gun, and in a creek near Daeheung Temple in Haenam-gun. The infection rate of crayfish with PwMc in Bogil-do was 89.8%, and the metacercarial burden was 37 PwMc per the infected crayfish. Crayfish in a creek near Daeheung Temple were larger and twice heavier than those in Bogil-do. Of them, 96.5% were infected with PwMc. An average of 140 metacercariae was found in the infected crayfish, almost quadruple to those of Bogil-do. There was a strong correlation between the number of PwMc and body weight of the crayfish. These results suggest that P. westermani metacercariae are still prevalent in crayfish of the 2 regions in Jeollanam-do, Korea.

Gill morphology in the red swamp freshwater crayfish procambarus clarkii (Crustacea: Decapoda: Cambarids) (Girard 1852) from the River Nile and its Branches in Egypt / Morfología de las branquias del cangrejo rojo de pantano de agua dulce procambarus clarkii (Crustacea: Decapoda: Cambarids) (Girard 1852) del Río Nilo y sus Ramas en Egipto

The aim of the present study was focused on and describes the gross morphological and scanning electron microscopical features of the gill of the red swamp freshwater crayfish. Our results noted that: all gills have the same general structure and appearance. The gill consists of axis with numerous finger-like filaments, having three morphological types; round, pointed and somewhat hooked shaped. There is a variation in the direction of filaments according to their position, in middle part were nearly perpendicular to gill axis while in the apex were nearly parallel to axis. There were characteristic system of gill spines on central axis, basal plate, setobranch and on the bilobed epipodal plate. There are four shape of spinated-like parts of setobranch seta, two pointed processes and two broad processes. The bilobed epipodal plate is devoid from any filaments and under SEM, its apical part has serrated free border and corrugated surface while the middle part has no serrated free border.

El objetivo del presente estudio fue describir las características morfológicas macroscópicas y mediante microscopio electrónico de barrido las branquias del cangrejo rojo de pantano de agua dulce. Nuestros resultados señalan que todas las branquias tienen la misma estructura y apariencia general. Las branquias se componen de ejes con numerosos filamentos similares a dedos, que tiene tres tipos morfológicos; redondo, punteado y con forma de gancho. Hay una variación en la dirección de los filamentos de acuerdo con su posición, en la parte media eran casi perpendicular al eje branquial, mientras que en el ápice fueron casi paralelas al eje. Hubo un sistema característico de espinas branquiales sobre el eje central, placa basal, espinas dorsales y sobre las placas epipodales bilobuladas. Se observaron cuatro formas de las ramas similares a espinas, dos procesos apuntados y dos procesos amplios. La placa epipodal bilobulada estaba desprovista de filamentos bajo microscopía electrónicas, su parte apical tiene una margen libre aserrado, con una superficie ondulada, mientras que la parte media no tiene margenes aserrados.

Clinical analysis of 197 cases of rhabdomyolysis induced by crayfish / 中华急诊医学杂志

Objective To summarize and evaluate the clinical features,therapeutic methods and prognosis of 197 cases with eating crayfish caused rhabdomyolysis in our hospital within July,2016 to August,2016.Methods Using retrospective method,197 rhabdomyolysis cases induced by eating crayfish were admitted into study.Data of epidemiological character,clinical features,therapy protocol and prognosis were collected and analyzed.Results All the patients had the experience of eating crayfish within 12h before the onset.Patients in this cohort had the common symptoms but varying degrees of myalgia,fatigue of the whole body muscles,and urine color change.Laboratory tests revealed:On day 1 of onset,serum myoglobin level had raised up to the peak with average level at (2 135 ± 1 547) μg/L (0-46 μg/L).Creatine kinase with average level at (4 657 ± 2 178) U/L (25-190 U/L);Aspartate transaminase with average level at 264 ± 83 U/L (10-45 U/L);Lactate dehydrogenase with average level at (1 457 ± 673) U/L (313-618 U/L),all these three markers reached peak on day 2,then gradually declined.All the patients recovered and discharged after relaxation,fluid infusion,alkalization of urine and dealing with the complications.Conclusion Timely diagnosis and treatment of the rhabdomyolysis syndrome induced by eating crayfish could indicate favorable prognosis in these patients from July,2016 to August,2016.

Molecular Description of Macroorchis spinulosus (Digenea: Nanophyetidae) Based on ITS1 Sequences

We performed a molecular genetic study on the sequences of 18S ribosomal RNA (ITS1 region) gene in 4-day-old adult worms of Macroorchis spinulosus recovered in mice experimentally infected with metacercariae from crayfish in Jeollanam-do Province, Korea. The metacercariae were round, 180 µm in average diameter, encysted with 2 layers of thick walls, but the stylet on the oral sucker was not clearly seen. The adult flukes were oval shape, and 760-820 µm long and 320-450 µm wide, with anterolateral location of 2 large testes. The phylogenetic tree based on ITS1 sequences of 6 M. spinulosus samples showed their distinguished position from other trematode species in GenBank. The most closely resembled group was Paragonimus spp. which also take crayfish or crabs as the second intermediate host. The present study is the first molecular characterization of M. spinulosus and provided a basis for further phylogenetic studies to compare with other trematode fauna in Korea.

Toxicity induced by dieldrin and chlorpyrifos in the freshwater crayfish Cambarellus montezumae (Cambaridae) / Toxicidad inducida por dieldrín y clorpirifós en Cambarellus montezumae (Cambaridae)

The toxicity induced by insecticides in aquatic organisms is of utmost relevance because it may give a clue about the degree of health or damage of the involved ecosystem. In the present report, we determined the effect of dieldrin (DD) and chlorpyrifos (CP) on the freshwater crayfish, Cambarellus montezumae. The organisms (4-6cm in diameter) were collected in the Ignacio Ramírez Reservoir, situated at 50km Northeast of Mexico City, in the Rio Lerma Basin. Initially, we determined the LC50 value with the Probit method, then the DNA damage with single cell gel electrophoresis (comet assay applied at 24, 48, and 72h of exposure) to the brain and hepatopancreas of animals exposed (in reconstituted water) to 0.05 and 0.5µg/L of each insecticide. In the hepatopancreas of the same organisms, we determined the lipid peroxidation by applying the TBARS test. DNA damage and lipid peroxidation were also evaluated with the same methods to organisms exposed in water from the reservoir. In regard to the LC50 at 72h of exposure, we found a value of 5.1µg/L and a value of 5.62µg/L for DD and CP, respectively. The comet assay applied at different exposure times showed significant DNA damage to both organs, with respect to the control level. In the case of DD, statistical significance was observed for the two doses in the whole evaluated schedule. CP was genotoxic in the brain with the high dose at 72h, and in the hepatopancreas with the two tested doses at all evaluated exposure times. Also, a significant lipid peroxidation increase was detected with the two doses of insecticides. In the study with water from the reservoir, a more pronounced DNA damage was detected. Our results showed strong DNA damage induced by both insecticides in the crayfish, as well as a correlation with the lipid peroxidation effect, suggesting that oxidative stress is involved in the genotoxic alteration. Our results also showed the usefulness of the studied organism as well as the applied tests for the evaluation of toxicological effects, and suggested the pertinence of applying the comet assay to other freshwater organisms to evaluate the bioaccumulation of insecticides. Rev. Biol. Trop. 63 (1): 83-96. Epub 2015 March 01.

La toxicidad inducida por insecticidas en organismos acuáticos es de gran relevancia porque puede orientar sobre el grado de salud o daño del ecosistema involucrado. En el presente estudio determinamos el efecto del dieldrín (DD) y del clorpirifós (CP) en el acocil de agua dulce Cambarellus montezumae. Los organismos (4-6cm de diámetro) se recolectaron en la Represa Ignacio Ramírez, situada a 50km al Noreste de la Ciudad de México, en la cuenca del Río Lerma. Inicialmente determinamos la LC50 con el método de Probit y después el daño al ADN mediante la electroforesis unicelular en gel (ensayo cometa, aplicado a las 24, 48 y 72 h de exposición) en el cerebro y el hepatopáncreas de animales expuestos (en agua reconstituida) a 0.05 y 0.5µg/L de cada insecticida. En el hepatopáncreas de los mismos organismos determinamos la peroxidación lipídica aplicando la prueba de TBARS. El daño al ADN y la peroxidación lipídica también se evaluaron con los mismos métodos en organismos expuestos a los insecticidas en agua de la represa. En relación a la LC50, a las 72h de exposición encontramos un valor de 5.1µg/L y un valor de 5.62µg/L para DD y CP, respectivamente. El ensayo cometa aplicado a diferentes tiempos de exposición mostró un significativo daño al ADN en ambos órganos con respecto al valor del testigo. En el caso del DD se observó significancia estadística para las dos dosis en todo el horario evaluado. CP fue genotóxico en el cerebro con la dosis más alta a las 72 h y en hepatopáncreas con las dos dosis, en todos los tiempos de exposición evaluados. También se detectó un significativo aumento de la peroxidación lipídica con las dos dosis de los insecticidas. En el estudio con el agua de la represa se detectó un daño más pronunciado en el ADN. Nuestros resultados mostraron un fuerte daño al ADN en Cambarellus montezumae por ambos insecticidas, así como una correlación con el efecto de la peroxidación lipídica, lo que sugiere que el estrés oxidativo está involucrado en la alteración genotóxica. Nuestros resultados también mostraron la utilidad del organismo estudiado y de las pruebas aplicadas para evaluar efectos tóxicos, y sugieren la pertinencia de aplicar el ensayo cometa en otros organismos de agua dulce para evaluar la bioacumulación de insecticidas.

DNA extraction from crayfish exoskeleton.

Crayfish exoskeleton (CE) samples are generally less invasive and easy to be collected. However, it is difficult to extract DNA from them. This study was intended to investigate CE as a DNA source and design an easy and efficient DNA extraction protocol for polymerase chain reactions. Specific primer pair (PPO-F, PPO-R) was used to amplify extracted DNA from CE, and compared to crayfish tail muscle DNA sample. Moreover, seven microsatellites markers were used to amplify the CE DNA samples set. Since the extracted DNA from CE is suitable for gene amplification, the results present usefulness of CE as an easy and convenient DNA source for PCR-based population genetic research.

Mitotic karyotype of the tropical freshwater crayfish Procambarus (Austrocambarus) llamasi (Decapoda: Cambaridae)

In Mexico, the biology of Procambarus has been more studied than the biology of other Cambarids because of its diversity and potential use in aquaculture. We determined the karyotype of the Mexican tropical freshwater crayfish Procambarus (Austrocambarus) llamasi from 189 metaphase spreads from gill tissues of 17 adults. They had 98-120 chromosomes (mode 2n=120 chromosomes). There are 60 pairs of monoarm, telocentric chromosomes. Sex chromosomes were not detected and we propose that the P. llamasi karyotype can be used to distinguish this species from other Mexican crayfish. Additionally, we suggest using karyological data in aquaculture and conservation biology. Rev. Biol. Trop. 58 (2): 655-662. Epub 2010 June 02.

El género Procambarus ha recibido mayor atención en los estudios de los principios fundamentales de su biología debido a su diversidad en el territorio mexicano y potencial uso en acuicultura. El cariotipo típico del acocil tropical mexicano Procambarus (Austrocambarus) llamasi, se estudió mediante 189 dispersiones cromosómicas en metafase del tejido branquial de 17 adultos tratados con la técnica citológica de inmersión. Encontramos un amplio número de cromosomas, que variaron entre 98-120 elementos cromosómicos, con número modal diploide de 2n=120 elementos cromosómicos. El cariotipo del acocil tropical esta constituido por 60 pares de cromosomas monorrámeos, todos los centrómero están en la región telocéntrica de los cromosomas. En las metafases mitóticas de hembras y machos no fueron identificados cromosomas sexuales. Sugerimos considerar la estructura cromosómica del cariotipo como una herramienta citotaxonómica así como el empleo de datos cariológicos para propósitos de acuicultura y conservación del acocil tropical.

Unexplained rhabdomyolysis: clinical analysis of twenty three cases / 中华急诊医学杂志

Objective To evaluate clinical features, therapeutic regimen and prognosis of unexplained rhabdomyolysis. Method Clinical manifestations, therapeutic regimen and prognosis were recorded in 23 patients,who were admitted to The First Affiliated Hospital of Nanjing Medical University 13 to 27 August,2010.The 23 patients were diagnozed as unexplained rhabdomyolysis. Results The patients all presented myalgia of upper body,like neck,waist and back,maybe with asthenia, nausea,dyspnea,abdominal pain, red urine or changed color of urine. Laboratory examination: obviously step-up of creatine kinase [CK: (4655 ± 2556) U/L( normal: 25 ～ 190U/L) AST:(141 ±78) U/L(normal:10～45 U/L),LDH:(348± 127) U/L(normal: 110～ 250 U/L)]and myoglobin[( Mb ＞ 1000 μg/L (normal: 0 ～ 50 μg/L)]. Therapeutic regimen included treatment of the underlying diseases, volume repletion, alkalization and dealing with the complications. No patients developed acute renal failure.All the patients recovered. Conclusions Rhabdomyolysis is a syndrome with different clinical manifestations.However, early diagnosis, proper treatment could prevent serious complications,and prognosis is good.

Infection Status of Freshwater Crabs and Crayfish with Metacercariae of Paragonimus westermani in Korea

The present study investigated the infection status of Paragonimus westermani metacercariae in freshwater crabs (n = 363) and crayfish (n = 31) from October 2007 to October 2008 using the crush method. All of the freshwater crabs, Eriocheir japonicus, were negative for P. westermani metacercariae while 10 (32.3%) of the 31 examined crayfish were positive. The 10 positive crayfish were caught in Haenam, Jeollanam-do, and there were 8-59 (mean 28.4) metacrcariae per infected crayfish. These results suggest that P. westermani metacerariae are still transmitted by crayfish enzootically in southern Korea, and that freshwater crabs may transmit metacercariae only on rare occasions.

A scanning electron microscopic study on the appendage morphology of Astacus leptodactylus (Eschscholtz, 1823) and Pacifastacus leniusculus (Daña, 1852) (Crustácea:Decapoda: Astacoidea)

This study compares the morphology of rostrum, pereipods 1,2,4 and mouthparts of juvenile Astacus leptodactylus with those oí Pacifastacus leniusculus. Differences in morphology were observed, in particular with regard to the mouthparts e.g. including setal armature and number of teeth on the mandible. In general, the shape of the rostra in the two species is similar in that both taper to a point with a pair of sharp spines distally. Laterally the rostrum of A. leptodactylus is bordered by a regular row of setae, which is not so well defined in P leniusculus. The observations also showed that in addition to an increase in size, changes in morphology in the feeding apparatus between the developmental stages of the two species were present. It was concluded that both species have similar rostra, but different setal patterns and there are differences between the two species in the armature of mouthparts as development progresses. Therefore, important differences in the morphology of mouthparts between P. leniusculus and A. leptodactylus and in the different stages of the species might cause a difference in the feeding behavior and food choice of the species.

Este estudio compara la morfología del rostro, pereiópodos 1,2,4 y piezas bucales de los Astacus leptodactylus jóvenes con los de Pacifastacus leniusculus. Se observaron las diferencias en la morfología, en particular, con respecto a las piezas bucales, por ejemplo incluyendo la armadura setal y el número de dientes en la mandíbula. En general, la forma del rostro en las dos especies es similar, tanto cónicas, como en punta, con un par de espinas distalmente. Lateralmente al rostro, A. leptodactylus está bordeada por un fila de setas, que no está tan bien definida en P leniusculus. Las observaciones también muestran que, además de un aumento en el tamaño, estaban presentes cambios en la morfología en el aparato masticatorio, entre las etapas de desarrollo de las dos especies. Se llegó a la conclusión que ambas especies tienen rostros similares, pero diferentes patrones setales y hay diferencias entre las dos especies en la armadura de piezas bucales como evolución del desarrollo. Por lo tanto, importantes diferencias en la morfología de piezas bucales entre P leniusculus y A. leptodactylus y en las distintas etapas de la especie podrían causar una diferencia en la conducta de alimentación y opciones de alimentación de la especie.

OBSERVATIONS OF INTRACELLULAR STIMULATING AND RECORDING BY TWO GLASS MICROELECTRODES ON THE CRAYFISH AXON / 西安交通大学学报(医学版)

Intracellular stimulating and recording method was used by two glass microelectrodes on crayfish small axon. Physiologic and physical parameters of small nerve fiber were measured. 4—aminopyridine (4-AP). a selective inhibitor of the potassium channel,made"b" (an irritability index,a constant in Weiss's formula) decreased(p