Effects of domestication and captive breeding on reaction to moving objects: implications for avoidance behaviours of masu salmon Oncorhynchus masou.

Domestication and captive breeding can compromise the obstacle- and predator-avoidance capabilities of animals in the wild. Whereas previous studies only examined these effects in combination, here we examine them individually by comparing the abilities of wild, F1 (offspring of wild parents) and captive-bred (approx. F15) masu salmon Oncorhynchus masou to avoid a falling object under experimental conditions. Rates of avoidance failure were low (wild, 12.5%; F1, 10.7%; captive-bred, 8%) under light conditions, but increased under dark conditions (wild, 11.1%; F1, 32.1%; captive-bred, 60.0%). We attribute the elevated avoidance failure rate among F1 fish to the lack of learning opportunities in hatchery environments (i.e. domestication), and the further elevation of avoidance failure rate among captive-bred fish to the degradation of sensory organ function (i.e. captive breeding). These results imply reduced survival rates for F1 and captive-bred fish in the wild and are consistent with the low stocking efficiencies reported for captive-bred masu salmon.

High-accuracy determination of trace elements by total reflection X-ray fluorescence spectrometry using freeze-dried specimens.

Total reflection X-ray fluorescence (TXRF) analysis is conducted to determine trace elements in a sample solution, which is dropped onto a substrate and dried. Therefore, the form of the residue affects the quantitative results. The absorption of X-ray fluorescence (XRF) follows the Lambert-Beer law; the absorption effect of XRF in a thick residue (dotted-type residue) is stronger than that in a thin residue (film-type residue). The absorption effect is particularly remarkable during the determination of low-Z elements in a high-elemental concentration solution. In this study, we propose a new film-like-residue preparation process based on the freeze-drying method to obtain accurate TXRF results. The sample solution is dropped onto the substrate and inserted into a chamber. The chamber is cooled using liquid nitrogen; resultantly, an aliquot of the sample is frozen. The chamber is depressurized using a vacuum pump, and the freeze-dried residue is prepared by maintaining the chamber at room temperature. To evaluate the efficiency of the freeze-drying-based method for sample preparation for TXRF analysis, we prepare a multi-element solution containing high-elemental concentration components. For the residue prepared using the freeze-drying method, the relative standard deviations of the quantitative values and the minimum detection limits are improved because the absorption effect is weakened. The sample preparation process based on the freeze-drying method facilitates accurate TXRF analysis of high-elemental concentration solutions and can be applied for the analysis of trace elements in different types of solutions such as environmental water and wastewater.

Domestication of captive-bred masu salmon Oncorhynchus masou masou (Salmonidae) leads to a significant decrease in numbers of lateral line organs.

Because captive-bred animals gradually adapt to artificial rearing environments due to evolving life history traits, such individuals sometimes show lessened performance in natural environments. The lateral line system, one of the principal sensory organs of fishes, varies according to habitat environments, sometimes differing even within the same species. A reduction in lateral line elements may also occur in successive generations of captive-bred fish. Such a reduction, involving neuromasts over the entire body, was examined for the first time in captive-bred masu salmon Oncorhynchus masou masou. The total number of neuromasts in captive-bred fish was ca. 10% lower than in wild-caught and F1 fishes, suggesting that the system in captive-bred fish had reduced in number due to domestication. Furthermore, differences in total neuromast numbers between captive-bred and wild fish were greater than between anadromous and fluvial populations of the species. The lower number of neuromasts could be one of the reasons behind the lower survival of captive-bred fish in natural environments.

The lateral line system and its innervation in the Japanese eel Anguilla japonica (Teleostei: Elopomorpha: Anguillidae).

The lateral line system and its innervation were examined in the Japanese eel Anguilla japonica. Although the species has seven lateral line canals and 13 superficial neuromast groups, the components are generally similar to those in many other teleosts. The lateral line system of A. japonica is distinctive in having a rostral commissure connecting the left and right supraorbital canals, pouches in the cephalic lateral line canals and superficial neuromasts along the lower lip, and lacking a postotic canal. Four tube-like elements, two along the supratemporal canal and the other two along the temporal portion of the trunk canal, respectively, are also reported. The functional significance of cephalic lateral line pouches, homologies of the four tube-like elements, and other distinctive characters are discussed.

The paedomorphic lateral line system in Pseudamiops and Gymnapogon (Percomorpha, Apogonidae), with morphological and molecular-based phylogenetic considerations.

The lateral line system and its innervation were examined in two paedomorphic species of Apogonidae, Gymnapogon japonicus and Pseudamiops cf. springeri, both of which have been included in Gymnapogonini (Apogoninae) characterized by a small translucent body lacking canalized lateral line scales, but with many superficial neuromasts (total SNs: 2,691 and 2,197 in G. japonicus and Pseudamiops cf. springeri, respectively). Although scales are entirely absent in G. japonicus, the innervation pattern of the trunk lateral line system is basically similar to that in other apogonids having a single lateral line scale series. In comparison, Pseudamiops cf. springeri (and P. gracilicauda) have three series of inconspicuous lateral line scales with a distinct innervation pattern, implying a phylogenetic affinity with Pseudamia (Pseudamiinae). The monophyly of Pseudamiops and Pseudamia was also supported strongly by a molecular phylogenetic analysis, thus the paedomorphic nature is considered homoplasy between Pseudamiops and Gymnapogon. The innervation of head lateral line system in G. japonicus and Pseudamiops cf. springeri is basically the same with that of other apogonids, supporting homology of the presence of many head SNs among the species. The SN pattern and head canals of adult Pseudamiops cf. springeri are similar to those in juvenile Pseudamia gelatinosa, implying a paedomorphic truncation of lateral line system development in Pseudamiops cf. springeri.

Non-destructive DNA extraction from herbarium specimens: a method particularly suitable for plants with small and fragile leaves.

Protocols for DNA extraction from plants generally involve physical and chemical destruction of tissues. Use of these conventional methods precludes preservation of morphological information from herbarium specimens, especially for small plants with few leaves, and reduces the voucher value of specimens. Here, we developed a new, non-destructive DNA extraction protocol (Protocol 1) that only needs a small piece of leaf (< 25 mm2) to obtain DNA suitable for DNA sequencing from fragile herbarium specimens. The protocol was very simple and rapid; an extraction buffer was placed on the leaf surface of an intact specimen for 30 min at room temperature (20 °C). The quality of extracted DNA was checked by PCR amplification of two standard plant DNA barcode regions, the maturase K gene (matK, ca. 850 bp) and the ribulose-1,5-bisphosphatecarboxylase/oxygenase gene (rbcL, ca. 550 bp), for 14 vascular plant species encompassing various taxonomic groups. The protocol retrieved sequences from 80.0% of specimens for matK and 46.2% of specimens for rbcL. Placing of the extraction buffer onto specimens did not cause any tears or deformation, but caused discoloration in some plants. To improve DNA yield for specimens incompatible with Protocol 1, we developed an alternative protocol for DNA extraction with minimally invasive destruction of specimens (Protocol 2). In this protocol, a cut leaf was immersed in the extraction buffer for 30 min and stored subsequently in a fragment pocket on the specimen sheet. This alternative method retrieved matK sequences from 80.0% of specimens and rbcL sequences from 92.8% of specimens. The combination of Protocols 1 and 2 enabled us to obtain matK sequences from 90.0% of specimens and rbcL sequences form 92.8% of specimens. The new protocols facilitate the use of museum specimens for use of DNA of museum specimens while still preserving morphological information.

Convergent evolution of the lateral line system in Apogonidae (Teleostei: Percomorpha) determined from innervation.

The lateral line system and its innervation were examined in two species of the family Apogonidae (Cercamia eremia [Apogoninae] and Pseudamia gelatinosa [Pseudamiinae]). Both species were characterized by numerous superficial neuromasts (SNs; total 2,717 in C. eremia; 9,650 in P. gelatinosa), including rows on the dorsal and ventral halves of the trunk, associated with one (in C. eremia) and three (in P. gelatinosa) reduced trunk canals. The pattern of SN innervation clearly demonstrated that the overall pattern of SN distribution had evolved convergently in the two species. In C. eremia, SN rows over the entire trunk were innervated by elongated branches of the dorsal longitudinal collector nerve (DLCN) anteriorly and lateral ramus posteriorly. In P. gelatinosa, the innervation pattern of the DLCN was mirrored on the ventral half of the trunk (ventral longitudinal collector nerve: VLCN). Elongated branches of the DLCN and VLCN innervated SN rows on the dorsal and ventral halves of the trunk, respectively. The reduced trunk canal(s) apparently had no direct relationship with the increase of SNs, because these branches originated deep to the lateral line scales, none innervating canal neuromast (CN) homologues on the surface of the scales. In P. gelatinosa, a CN (or an SN row: CN homologue) occurred on every other one of their small lateral line scales, while congeners (P. hayashii and P. zonata) had an SN row (CN homologue) on every one of their large lateral line scales.

Simultaneous production of two kinds of sounds in relation with sonic mechanism in the boxfish Ostracion meleagris and O. cubicus.

In fishes, sonic abilities for communication purpose usually involve a single mechanism. We describe here the sonic mechanism and sounds in two species of boxfish, the spotted trunkfish Ostracion meleagris and the yellow boxfish Ostracion cubicus. The sonic mechanism utilizes a T-shaped swimbladder with a swimbladder fenestra and two separate sonic muscle pairs. Extrinsic vertical muscles attach to the vertebral column and the swimbladder. Perpendicularly and below these muscles, longitudinal intrinsic muscles cover the swimbladder fenestra. Sounds are exceptional since they are made of two distinct types produced in a sequence. In both species, humming sounds consist of long series (up to 45 s) of hundreds of regular low-amplitude pulses. Hums are often interspersed with irregular click sounds with an amplitude that is ten times greater in O. meleagris and forty times greater in O. cubicus. There is no relationship between fish size and many acoustic characteristics because muscle contraction rate dictates the fundamental frequency. We suggest that hums and clicks are produced by either separate muscles or by a combination of the two. The mechanism complexity supports an investment of boxfish in this communication channel and underline sounds as having important functions in their way of life.

Laterality is Universal Among Fishes but Increasingly Cryptic Among Derived Groups.

Laterality has been studied in several vertebrates, mainly in terms of brain lateralization and behavioral laterality, but morphological asymmetry has not been extensively investigated. Asymmetry in fishes was first described in scale-eating cichlids from Lake Tanganyika, in the form of bilateral dimorphism in which some individuals, when opening their mouths, twist them to the right and others to the left. This asymmetry has a genetic basis, and is correlated with lateralized attack behaviors. This has subsequently been found in fishes from numerous taxa with various feeding habits. The generality of such morphological laterality should thus be investigated in as wide a range of fishes as possible. Using specific indicators of lateral differences in mandibles and head inclination, we find that representative species from all 60 orders of extant gnathostome fishes (both bony and cartilaginous) possess morphological laterality. Furthermore, we identify the same laterality in agnathans (hagfish and lamprey), suggesting that this trait appeared early in fish evolution and has been maintained across fish lineages. However, a comparison of asymmetry among groups of bony fishes reveals, unexpectedly, that phylogenetically more recent-groups possess less asymmetry in body structures. The universality of laterality in fishes indicates a monophyletic origin, and may have been present in the ancestors of vertebrates. Ecological factors, predator-prey interactions in particular, may be key drivers in the evolution and maintenance of dimorphism, and may also be responsible for the cryptic trend of asymmetry in derived groups. Because lungfish and coelacanths share this trait, it is likely that tetrapods also inherited it. We believe that study of this morphological laterality will provide insights into the behavioral and sensory lateralization of vertebrates.

Ichthyofauna of the Kubo, Tochikura, and Ichinono river systems (Kitakami River drainage, northern Japan), with a comparison of predicted and surveyed species richness.

The potential fish species pool of the Kubo, Tochikura, and Ichinono river systems (tributaries of the Iwai River, Kitakami River drainage), Iwate Prefecture, northern Japan, was compared with the observed ichthyofauna by using historical records and new field surveys. Based on the literature survey, the potential species pool comprised 24 species/subspecies but only 20, including 7 non-native taxa, were recorded during the fieldwork. The absence during the survey of 11 species/subspecies from the potential species pool suggested either that sampling effort was insufficient, or that accurate determination of the potential species pool was hindered by lack of biogeographic data and ecological data related to the habitat use of the species. With respect to freshwater fish conservation in the area, Lethenteronreissneri, Carassiusauratusbuergeri, Pseudorasborapumila, Tachysurustokiensis, Oryziaslatipes, and Cottusnozawae are regarded as priority species, and Cyprinusrubrofuscus, Pseudorasboraparva, and Micropterussalmoides as targets for removal.

Muscular system in the pacific bluefin tuna Thunnus orientalis (Teleostei: Scombridae).

The muscular system in the Pacific bluefin tuna Thunnus orientalis is studied in detail. For the first time, a complete description of the muscular anatomy of a thunnid is provided here. Eighty-two elements including subdivisions of components of the muscular system are identified. This is less than found in a basal perciform and two other investigated scombrid species, owing mainly to the absence or fusion of pectoral, pelvic and caudal fin muscles. The absence of elements of the basal perciform pattern was most prominent in the caudal fin, which includes only the flexor dorsalis, flexor ventralis, hypochordal longitudinalis, and interradialis. In the caudal fin, the medial fan-shaped ray was identified as the first dorsal ray, judging from myological and neuroanatomical characters. The highly developed gill filament muscles in Thunnus orientalis and sheet-like rectus communis control gill ventilation. Long body muscle tendons reduce the metabolic energy needed during rapid and continuous swimming. These characters are interpreted as adaptations in the context of the oceanic life style of the species.

Homologies of the branchial arch muscles in Zacco platypus (Teleostei: Cypriniformes: Cyprinidae): evidence from innervation pattern.

Homologies of the branchial arch muscles in the cyprinid Zacco platypus are assessed based on their innervation. Muscles serving the first gill arch are innervated by branches of the glossopharyngeal (IX) nerve and those serving other arches by the vagal (X) nerve. Absence of the levator posterior is confirmed. Five pairs of muscles originating from the cranium and inserted onto the specialized 5th ceratobranchial, all unique to cyprinids, are innervated by the 4th branchial trunks of X, indicating that all pairs are derivatives of the sphincter oesophagi, involving reorganization from intrinsic to extrinsic elements. Homologies of some ventral branchial muscles are also discussed and the criteria for homology improved by clarifying the innervation pattern.

Lateral line system and its innervation in Tetraodontiformes with outgroup comparisons: descriptions and phylogenetic implications.

The lateral line system and its innervation in ten tetraodontiform families and five outgroup taxa were examined. Although some homology issues remained unresolved, tetraodontiforms were characterized by having two types (at least) of superficial neuromasts (defined by the presence or absence of supporting structures) and accessory lateral lines and neuromasts (except Molidae in which "accessory" elements were absent). The preopercular line in Tetraodontiformes was not homologous with that of typical teleosts, because the line was innervated by the opercular ramule that was newly derived from the mandibular ramus, the condition being identical to that in Lophiidae. Within Tetraodontiformes, the number of neuromasts varied between 70 and 277 in the main lines and between 0 and 52 in accessory elements. Variations were also recognized in the presence or absence of the supraorbital commissure, mandibular line, otic line, postotic line, ventral trunk line, and some lateral line nerve rami, most notably the dorsal branch of the opercular ramule, being absent in Aracanidae, Ostraciidae, Tetraodontidae, Diodontidae, and Molidae. Morphological characteristics derived from the lateral line system and its innervation provided some support for a sister relationship of tetraodontiforms with lophiiforms.

Branchial arch muscle innervation by the glossopharyngeal (IX) and vagal (X) nerves in tetraodontiformes, with special reference to muscle homologies.

Branchial arch muscle innervation by the glossopharyngeal (IX) and vagal (X) nerves in 10 tetraodontiform families and five outgroup taxa was examined, with special reference to muscle homologies. Basic innervation patterns and their variations were described for all muscle elements (except gill filament muscles). In the tetraodontids Takifugu poecilonotus and Canthigaster rivulata, diodontid Diodon holocanthus, and molid Mola mola, levator externus 4 was innervated by the 3rd vagal branchial trunk (BX3) in addition to BX2, owing to strong posterior expansion of the muscle. Based on nerve innervation, migrations of the muscle attachment sites (i.e., origins and insertions) were recognized in levator internus 2 (in Mola mola), obliquus dorsalis 3 (in Ostracion immaculatus and Canthigaster rivulata), and obliquus ventralis 2 (in Stephanolepis cirrhifer), muscle topologies not necessarily being indicative of homologies. Embryonic origin of the retractor dorsalis and parallel attainment of the swimbladder muscle within the order were also discussed.

Functional analysis of recombinant pancreatic secretory trypsin inhibitor protein with amino-acid substitution.

BACKGROUND: We hypothesized that mutation of the pancreatic secretory trypsin inhibitor ( PSTI) gene may promote a predisposition to pancreatitis, possibly by reducing the inhibition of trypsin activity. Based on this hypothesis, we performed a biochemical analysis of recombinant PSTI protein. METHODS: The trypsin inhibitory activity of the recombinant protein was analyzed. The activity of PSTI protein with a point mutation of the most common type: (34)Asn (AAT)-to-Ser (AGT)(101A>G N34S: N34S) in exon 3, was compared with that of the wild type. RESULTS: The function of N34S PSTI remained unchanged under both the usual alkaline and acidic conditions compared with the wild-type PSTI. The calcium concentration did not affect the activity of recombinant PSTI. The trypsin susceptibility of the N34S protein was not increased either. CONCLUSIONS: Mechanisms other than the conformational change of PSTI associated with amino-acid substitution, such as abnormal splicing, may underlie the predisposition to pancreatitis in patients with the N34S mutation.