Peculiarities of early ontogenesis of the tubenose poacher, <Emphasis Type="Italic">Pallasina barbata</Emphasis> steindachner, 1876 (Pisces,Agonidae) from Peter the Great Bay (Sea of Japan)

Based on the analysis of original material (52 specimens of Pallasina barbata larvae and juveniles), sampled in the Peter the Great Bay (Sea of Japan) from 1992 to 2006, the ontogenetic stages of this species were described for the first time. It is shown that P. barbata has a planktonic larval stage in its development. The major morphologic features that are typical for larvae and juveniles during their development were revealed. It was shown that snout length, head length and pectoral fin size are increased with growth; at the same time body height and eye diameter are decreased, and the nature of larval pigmentation is changed. The main differences between P. barbata and close species are shown. Original illustrations of larvae and juvenile are provided.     

Mechanism of inhibition of purified leaping mullet (Liza saliens) NADPH-cytochrome P450 reductase by toxic metals: aluminum and thallium

Aluminum and thallium may reach life-threatening levels in aquatic systems in the near future because of their extensive use in various industrial fields. It is therefore important to study the mechanism of toxicity of aluminum and thallium on fish enzymes. To this aim, the effects of aluminum and thallium on the activity of purified leaping mullet (Liza saliens) cytochrome P450 reductase, an essential component of the important cytochrome P450 system, have been studied. Results indicated that both metal ions strongly inhibited the NADPH-cytochrome P450 reductase. The IC50 values of AlCl3 and TlCl3 were estimated to be 34 microM and 3 microM, respectively. The Lineweaver-Burk plot and Dixon plot revealed that both metal ions noncompetitively inhibited the purified mullet cytochrome P450 reductase. The K(i) values of Al3+ and Tl3+ were calculated from Dixon plots as 8.9 and 5.6 microM, respectively. The inhibitory effects of Al3+ and Tl3+ on purified cytochrome P450 reductase were partially recovered by 1 mM EDTA. Additionally, tin and magnesium were shown to have no apparent effect on purified mullet cytochrome P450 reductase.     

Detecting immigrants in a highly genetically homogeneous spiny lobster population (Palinurus elephas) in the northwest Mediterranean Sea

We investigated the genetic structure of early benthic juveniles of the spiny lobster Palinurus elephas in the northwest Mediterranean Sea by means of ten polymorphic microsatellite markers. Non‐metric Multidimensional Scaling coupled with assignment tests were used as a new approach to further delimit a reference population inside a genetically homogeneous pool of individuals and test for the presence of long distance immigrants. From this approach, we found that most early benthic juveniles collected while settling in the northwest Mediterranean Sea originated from a common larval pool. However, 4.2% of the individuals were classified as immigrants from other genetically differentiated populations, with more immigrants in the south than in the north of the sampled basin. Given currents in the northwest Mediterranean Sea and the long pelagic larval phase of P. elephas that lasts several months, this result suggest a restricted homogenized zone in the studied basin with some individuals probably coming from more differentiated populations through the Almeria‐Oran Front or the Strait of Sicily.     

Age-dependent patterns of intensive observation on elders by free-ranging juvenile Japanese macaques (Macaca fuscata yakui) within foraging context on Yakushima

Early learning about edible food in the environment is a critical survival task for young nonhuman primates. Social learning and social facilitation are often cited to explain how youngsters learn to select and find their food. In this framework, we observed eight mother-youngster pairs of free-ranging Japanese macaques divided into two sets according to the age of the young (infants aged between 7 and 12 months and juveniles aged between 1.5 and 2 years) during three winter months. We systematically investigated the intensive observation directed by the youngsters toward elders by recording the target's identity (e.g. mother, subadult), the items manipulated by the elder and those items closely observed by the youngster, along with the behavior of the youngster preceding and immediately following an intensive observation period. The diet of the mothers and juveniles was estimated from time records of each feeding occurrence for each food item (identified to species level) and from the quantity of fresh matter ingested. The results show that intensive observation by both infants and juveniles were directed toward those elders engaged in plant and invertebrate foraging. Such behavior was age-dependent, being more frequent in infants than in juveniles. The majority of the intensive observations were directed toward the mother. Intensive observations also shaped a change in the behavior of infants by significantly stimulating the investigation of food items and locations otherwise not investigated by juveniles. Moreover, infants showed a particular interest in rare food items and especially invertebrates. Age differences between the two sets of young and their interest in rare foods are discussed with reference to the occurrence of intensive observation within the framework of kin relationships, social organization, and social transmission of information about food type and food location and its survival values.     

Natal emigration by both sexes in the La Pacifica population of mantled howlers: when do some stay?

We have reported previously that all male and female mantled howlers emigrate from natal groups at Hacienda La Pacifica, Costa Rica. In the years since that report, a small number of juveniles have stayed in the natal group without experiencing a solitary phase. Here, we present a post hoc analysis on juvenile emigration in six groups of howlers under observation for varying amounts of time between 1972 and 2005. Our records revealed 139 juveniles for whom emigration status was certain, and 125 of these did emigrate. There was a significant association between presence of mother and emigration: juveniles without mothers were more likely to remain in their natal group (chi(1)(2) = 53.1, P<.0001). The mean age of emigration for all juveniles (n = 125) was 2.47 years (SD = 0.9, range = 1.5-6.5). There was no difference in age of emigration by adult male composition (one-male, multi-male, both), but juveniles of unknown sex emigrated younger than either known males or females (F(2,116) = 4.4, P<.02). For emigrating juveniles of known sex (n = 99), both males and females without mothers left at a later age than those with mothers (F(1,95) = 6.5, P<.02). Although philopatry or delayed emigration occurs in a few motherless animals, most males and females do emigrate from their natal groups at ages consistent with those reported for other species of howlers.     

鲻和鲮鳃丝的扫描电镜比较观察

对鲻（Mugil cephalus）和鲮（Cirrhina molitorella）的鳃丝表面结构进行了扫描电镜比较观察,结果表明,鲻鳃丝杆状部比鲮粗．鲻鳃小片高度比鲮低;两者鳃丝表面分泌孔洞口径和密度不同;鲻和鲮细胞外被不同,鲻细胞外被稀疏,鲮的则致密复杂;鳃小片细胞和鳃丝表皮细胞的表面形态存在差异,文章还描述了鳃丝表皮形态特异的细胞。     

Evaluation of a sweep net electrofishing method for the collection of small fish and shrimp in lotic freshwater environments

A major limitation of methods for collecting small fish and shrimp is that no single method is equally effective for all species or all life history stages. We compared the efficacy of the sweep net electrofishing (SNE) method with two other commonly used sampling methods for the collection of small fish and shrimp, the standard sweep net (SW) and the point abundance electrofishing (PAE) method developed by Copp & Penaz (1988). The effectiveness of the three methods was compared under three different current speeds in an Australian lowland river. The SNE method collected an order of magnitude more shrimp and a greater size range than the other two methods, irrespective of the current speed. The SNE method captured a similar number of fish to the SW method, but significantly more individuals than the PAE method. However, the two electrofishing methods caught a greater size range of both fish and shrimp than did the SW method. The effectiveness of the SNE method appears to be due to its ability to immediately capture shocked individuals, thereby lessening the likelihood of escape. Whilst the SNE method is not quantitative, its high level of effectiveness is likely to be particularly useful in systems with low densities of fish and shrimp.     

Ontogenetic behavior of Siberian sturgeon, Acipenser baerii: A synthesis between laboratory tests and field data

We have reviewed field data and studies on the behavior and development of Siberian sturgeon at early-life intervals and related them to different ecologically relevant environmental factors that may play a role in the distribution, recruitment, and survival of young fish. Four behavioral phases (swimming-up, rheotactism, shoaling, and foraging) are observed from hatching to the juvenile phase. Each behavior is associated with an early-life interval and might allow fish to occupy different river habitats, directly influencing their distribution, survival, and recruitment. River current intensity, substrate typology, food resources, and predation pressure seem to be the most important factors affecting the distribution of Siberian sturgeon free embryos and larvae, while juveniles and adult fish disperse and migrate according to food abundance and reproduction. Mechanisms involved in regulating downstream migration during Siberian sturgeon early life stages are different than those observed in anadromous sturgeon species. In all large Siberian rivers, with the exception of the Lake Baikal, the Siberian sturgeon is represented by population continuums, and in many cases the foraging range also includes the spawning areas. Ontogenetic changes in Siberian sturgeon behavior could be interpreted as a species-specific mechanism to maintain the population continuums described in this species without significant mixture of local populations within the river.     

The mixed dentition and associated skull fragments of a juvenile fossil hominid from Sterkfontein,South Africa

In April–May 1983, the late A.R. Hughes and his field team recovered more than 40 bone fragments and teeth from a single solution pocket of the Sterkfontein Formation. After preparation and reconstruction by JMC, it was recognised that these fragments represent a single juvenile individual (Stw 151), consisting of more than 40 cranial and dental parts, with mixed dentition. It constitutes the most complete set of jaws and teeth of an early hominid child since the Taung child was recovered in 1924. In this paper, the morphological and metrical features of the individual teeth are described. The other associated skull fragments (right ramus of the mandible, left petrous bone, right glenoid region) are also described. Comparisons are made with other South (and East) African fossil hominids. The beautiful preservation simultaneously of most of the deciduous teeth and of the permanent teeth exposed in their crypts allows an accurate analysis of the developmental sequence. A report on the dental developmental status of this juvenile is presented. On the basis of the microanatomical study of the developing permanent teeth, the estimated age at death is 5.2–5.3 years. Reconstructions of the maxillary and mandibular arcades are also offered. The morphological and metrical features of Stw 151 raise the possibility that it may represent a hominid more derived towards an early Homo condition than the rest of the A. africanus sample from Member 4. Am J Phys Anthropol 106:425–465, 1998. © 1998 Wiley-Liss, Inc.     

Purification and Characterization of Cytochrome P450 Reductase from Liver Microsomes of Feral Leaping Mullet (Liza saliens)

NADPH-cytochrome P450 reductase was purified to electrophoretic homogeneity from detergent-solubilized liver microsomes from the leaping mullet (Liza saliens). The purified reductase was characterized with respect to spectral, electrophoretic, and biocatalytic properties. In addition, effects of pH, ionic strength, and the substrate concentration on the NADPH-dependent cytochrome c reductase activity of the purified fish liver cytochrome P450 reductase were studied. Cytochrome P450 reductase was purified 438-fold with a yield of 17.5% with respect to the initial amount present in the fish liver microsomes. The specific activity of the enzyme was found to be 52.6 μmol cytochrome c reduced per minute per mg protein. The monomer molecular weight of the purified enzyme was calculated to be 77,000 ± 1000 when electrophoresed on polyacrylamide gels under the denaturing conditions in the presence of SDS. The absorption spectrum of fish reductase showed two peaks at 378 and 455 nm. NADPH-dependent cytochrome c reductase activity of the purified Liza saliens liver cytochrome P450 reductase was found to be maximal when pH was between 7.4 and 7.8. The apparent K_m of the purified enzyme was found to be 7.69 μM for cytochrome c when the enzyme activity was measured in 0.3 M potassium phosphate buffer, pH 7.7, at room temperature, and the enzyme was fully saturated by its substrate, cytochrome c, when the substrate concentration was at or above the 70 μM. Furthermore, the purified enzyme was biocatalytically active in reconstituting the 7-ethoxyresorufin O-deethylase activity in the reconstituted system containing purified mullet liver cytochrome P4501A1 and lipid. These results suggested that the purified fish liver cytochrome P450 reductase is similar to its mammalian counterparts with respect to spectral, electrophoretic, and biocatalytic properties. © 1997 John Wiley & Sons, Inc. J Biochem Toxicol 12: 103–113, 1998