A first record of anchialine crab of the genus Orcovita Ng and Tomascik, 1994 (Decapoda: Brachyura: Varunidae) from Japan, with description of the species

Orcovita miruku, new species, is described from Ishigaki Island, southern Ryukyu Islands, Japan. Orcovita miruku is easily distinguished from the other congeners by the presence of three teeth (including external orbital angle) on the anterolateral margin of the carapace. Orcovita angulata may be allied to O. miruku, but there are a number of differences in the characters of the carapace and the ambulatory legs. The holotype, obtained from an anchiline pool in a limestone excavation, is the only specimen collected thus far, and this is the first record of an anchiline crab from Japan.     

Application of a microfluidic sperm sorter to the in-vitro fertilization of porcine oocytes reduced the incidence of polyspermic penetration

The objective of this study was to use a microfluidic sperm sorter (MFSS), designed to isolate motile human spermatozoa with laminar flows (no centrifugation), for porcine IVF. Boar spermatozoa were diluted at 1 × 10⁸ cells/mL with a diluent containing 20% seminal fluid and flowed with modified TCM-199 (mM199, with 5 mM caffeine) to introduce motile sperm into the exit chamber for IVF. In Experiment 1, after flowing for 5 min, sperm concentration varied significantly among specific sites within the MFSS collecting chamber (range, 0.8 ± 0.5 × 10⁴ to 575.0 ± 56.3 × 10⁴ cells/mL; mean ± SEM). In Experiment 2, when porcine IVM oocytes were placed at three locations in the MFSS exit chamber (where only motile spermatozoa accumulated) and subsequently cultured in caffeine-free mM199 for 8 h, sperm penetration rate was not significantly different among places (86.1 ± 10.5 to 100%), but the monospermic penetration rate was lower (P < 0.05) in oocytes 3.5 mm from the exit position (12.5 ± 4.8%) than those at 7.5 mm (53.1 ± 6.0%) or further (41.9 ± 2.8%) from the exit. In Experiment 3, the normal fertilization index (ratio of monospermic oocytes to number of oocytes examined) 8 h after insemination was higher (P < 0.05) in the MFSS-IVF system (0.375 ± 0.040) than both standard IVF and transient IVF (0.222 ± 0.028 and 0.189 ± 0.027, respectively, with co-culture for 8 h and for 5 min). Developmental competence of fertilized oocytes (blastocyst formation) was higher (P < 0.05) in the MFSS-IVF system (40.9 ± 2.3%) than in either standard or transient IVF (22.6 ± 1.4 and 33.7 ± 3.5%). In conclusion, brief co-culture of porcine oocytes with spermatozoa gradually accumulated in the MFSS chamber improved the efficiency of producing monospermic fertilized embryos and blastocysts. Furthermore, efficiencies were significantly affected by oocyte location within the chamber.     

胰管细胞HCO3-分泌:囊性纤维化跨膜电导调节体和SLC26转运体

胰管细胞以至少6倍浓度差逆向分泌HCO3^-（人体浓度约140mmol／L）。HCO3^-跨顶膜转运的可能机制包括SLC26阴离子转运体的Cl-HCO3^-交换和囊性纤维化跨膜电导调节体（cystic fibrosis transmembrane conductance regulator,cFrR）对HCO3^-的传导扩散。SLC26家族成员介导上皮顶膜Cl^--HCO3^-交换,胰管中检测到SLC26A6和SLC26A3。共表达研究揭示,鼠类slc26a6和slc26a3通过slc26的STAS结构域与CFTR的R结构域相互作用,导致活性互相增强。研究显示这些交换体是产电的：slc26a6介导1Cl^--2HCO3^-交换,slc26a3介导2Cl^--1HCO3^-交换。近期slc26a6^-／-小鼠离体胰管研究显示,slc26a6介导大部分Cl^-依赖的HCO3^-跨顶膜分泌,与slc26a6的产电性一致。然而,因为人体能分泌非常高浓度的HCO3^-,SLC26A6在胰管HCO3^-分泌中的作用并不十分清楚。SLC26A6的作用只能在与人类似能分泌约140mmol／LHCO3^-的物种,如豚鼠中研究。现有的豚鼠研究数据显示,像slc26a6介导的1Cl^--2HCO3^-交换不可能完成这种高浓度差的HCO3^-分泌。另一方面,CFTR的HCO3^-电导性可以在理论上支持HCO3^-逆向分泌。所以,在豚鼠和人胰腺HCO3^-的分泌中,CFTR可能比SLC26A6发挥更大作用。     

Experimental induction of two inner cell masses in mouse embryos by vinblastine treatment in vitro

Induction of artificial fission of the inner cell mass in an in vitro embryonal culture system was attempted. Mouse blastocysts were collected from uteri on day 3 of gestation and exposed to vinblastine sulfate after removal of zona pellucida. Embryos in the control group had a single inner cell mass on the trophectoderm and developed to the postblastocyst stage. On the other hand, the inner cell masses of the embryos in experimental groups subdivided into two or more. The present results, therefore, revealed that the vinblastine treatment at the blastocyst stage induced fission of the inner cell mass in mouse embryos. Further studies are planned in improved culture conditions to determine whether each inner cell mass subdivision develops into independent embryos.     

High-performance liquid chromatographic determination of α-keto acids in human urine and plasma

A high-performance liquid chromatographic method has been developed for the determination of α-keto acids in human urine and plasma. These acids were prepurified using a column of hydrazide gel and derivatized with o-phenylenediamine into 2-quinoxalinol derivatives, which were extracted into ethyl acetate. The 2-quinoxialinol derivatives were separated by reversed-phase paired-ion chromatography using a 250 × 4 mm-i.d. column packed with LiChrosorb RP-8 (5 μm). This method is sensitive, selective, and reproducible. The α-keto acids in urine and plasma from normal individuals were determined.     

High-performance liquid chromatographic determination of α-keto acids

A high-performance liquid chromatographic method has been developed for the determination of eight kinds of α-keto acids. These acids were derivatized with o-phenylenediamine into 2-quinoxalinol derivatives, which were extracted into chloroform. The quinoxalinol derivatives were separated by reversed-phase high-performance liquid chromatography using a 250 mm × 2.1 mm I.D. column packed with LiChrosorb RP-8 (5 μm). This method could be satisfactorily applied to urine samples without any prepurification.     

Possible involvement of the ampullary electroreceptor system in detection of frequency-modulated electrocommunication signals in Eigenmannia

Behavioral and electrophysiological experiments were conducted to examine whether frequency-modulated electrocommunication signals are detected by the ampullary electroreceptor system in Eigenmannia. First, frequency-modulated electric organ discharges were found to contain a low-frequency component that could be detected by the ampullary system. Second, fish were successfully trained to distinguish a frequency-modulated signal, which contained a low-frequency component as in natural signals, from an artificial signal in which the low-frequency component was eliminated but still modulated in frequency. Subsequently, the trained fish responded without reinforcement to a low-frequency sinusoidal signal which mimicked the low-frequency component in the frequency-modulated signal, suggesting that the fish used the ampullary system to detect frequency modulation. Finally, physiological recording from ampullary afferent fibers demonstrated that they respond to frequency-modulated signals as predicted from the signal's low-frequency component. Electrophysiological study also showed that detection of frequency modulation by the ampullary system is immune to the presence of other constant electric organ discharges. Accepted: 28 June 1998     

Annual and daily activity rhythms of loathes in an irrigation creek and ditches around paddy fields

Synopsis This study deals with the daily activity rhythm and its change in a loath,Misgurnus anguillicaudatus, by season and age. We set traps in an irrigation creek and ditches around the paddy fields near Nara city every month for 2 years. The fish appeared in spring, declined in early summer, and increased in mid-summer again, and disappeared in late autumn. The number of fish captured at night was greater than that during the daytime in summer. There were some differences in the daily rhythms by sex and age. Nocturnal activities of males and immatures were more prominent than those of females. Younger generation were more nocturnally active than elders in summer. Changes in the daily activity rhythms of the loath are possibly adaptive to unstable environments around paddy fields.