Ontogenetic change in the relationship between metabolic rate and body mass in a sea bream Pagrus major (Temminck & Schlegel)

Ontogenetic changes in the relationship between resting rate of oxygen consumption and wet body mass were examined at 20° C with the sea bream Pagrus major ranging from 0.00020 g (weight just after hatching) to 270 g (weight at 530 days old). There was a triphasic relationship between oxygen consumption of an individual fish M (μl min⁻¹) and body mass W (g). During a very early stage (weight 0.00020–0.00025 g), corresponding to the pre-larval stage and with the transitional period to the post-larval stage, there was no substantial change in body mass. The mass–specific metabolic rate M/W (μl g⁻¹ min ¹) showed no clear relationship to body mass as expressed by the equation M/ W =4.86 + 1.47 D , where D is age in days. During the post-larval stage (weight 0.00031–0.005 g), M/W remained almost constant independent of body mass following the expression M = 12.5 W0 .949. During the juvenile and later stages (weight 0.005–270 g), M/ W decreased with increasing body mass following the expression M = 6.3 W ^0.821 which is significantly different from the expression for the post-larval stage ( P < 0.001). Ontogenetic changes in the metabolism-body mass relationship are discussed from the viewpoint of relative growth of organs with different metabolic activities.     

Functional morphology of gills and respiratory area of two active rheophilic fish species, Plagioscion squamosissimus and Prochilodus scrofa

Measurements of gill dimensions were carried out on two ecologically distinct active rheophilic teleost species, the curvina Plagioscion squamosissimus and the curimbatá Prochilodus scrofa , and were analysed in relation to body mass according to the equation Y=aW^b . The gill respiratory areas of P. squamosissimus and P. scrofa were large as expected for active fish and increased with increasing body mass ( b =0.70 and 0.72, respectively) showing no significant difference between them. However, the large respiratory area of both species was realized in a different way revealing an adaptation to the plasticity of head components related to feeding habits. Consequently, significant differences were found between the number and average length of gill filaments and the bilateral area of secondary lamellae. The respiratory area of P. scrofa was due mainly to larger bilateral surface area of the secondary lamellae and its growth coefficient ( b =0.51) that was significantly higher ( P <0.05) than that found for P. squamosissimus ( b = 0.36). The frequency of secondary lamellae mm⁻¹ of filament was similar in both species (22 ± 2 on one side of gill filament). The dimensions of gill components and the respiratory area of these species suggest a complex interaction between head form, and feeding habits related to the functional morphology of the gills to meet the oxygen requirements of each species.     

Relative growth of organs and parts of a marine teleost,the porgy,Pagrus major,with special reference to metabolism-size relationships

Organ-body mass relationships were examined for 36 different organs and parts in porgies,Pagrus major, ranging in body mass from 0.0033 to 1200 g. Organs with high metabolic activity, e.g. brain, intestine, pyloric caeca and heart showed negative allometry except during very early stages in the life history. On the other hand, the trunk, which comprised mainly musculature with low metabolic activity, showed positive allometry. These results support our idea that the decline in mass-specific metabolic rate in animals with increasing body mass can be explained, partly at least, by tissues with low metabolic rates becoming heavier in proportion to the whole body with growth.     

Evidence of daily spawning in natural populations of the New Zealand snapper Pagrus auratus (Sparidae)

Synopsis New Zealand snapper, Pagrus auratus, were captured by trawling from NE New Zealand over two successive spawning seasons, and examined for acute temporal changes in gonad condition. Fish with oocytes completing final oocyte maturation predominated during the morning, with a peak in ovulated fish occurring just after midday. Afternoon catches were dominated by fish in which the most advanced oocytes had yet to begin final maturation. This suggests that ovulation is synchronised to occur soon after midday, and the high proportion (up to 100% of the catch) of fish with particular gonad stages captured at any one time indicates that daily spawning involves most of the population. Diurnal changes in oocyte diameter support a daily spawning rhythm, with numbers of large hydrated oocytes peaking in the late morning, followed by the disappearance of these oocyte stages in the afternoon. Snapper captured alive by longlining were returned to the laboratory to examine the relationship between ovulation and probable time of spawning. Unovulated fish generally ovulated close to midday on the day of capture (morning captures), or the following day (afternoon captures). The viability of ovulated eggs (proportion undergoing division after fertilization) decreased markedly after oviduct residence times of over 8 hours. This suggests that natural spawning occurs before the late evening. The results of this study are consistent with anecdotal evidence suggesting that spawning occurs every day during the late afternoon or early evening, and is similar to the reproductive patterns displayed by a number of closely related sparids. Department of Zoology, University of Otago, PO Box 56, Dunedin, New Zealand     

Isolation and detection of Leishmania species among naturally infected Rhombomis opimus, a reservoir host of zoonotic cutaneous leishmaniasis in Turkemen Sahara, North East of Iran

In Iran, three species of Leishmania have been incriminated as the causative agents of human leishmaniasis, Leishmania (L.) major, Leishmania tropica, and Leishmania infantum.Rhombomis opimus have been incriminated as a principal reservoirs of the parasitic protozoan Leishmania major, the causative agent of rural zoonotic cutaneous leishmaniasis (ZCL) in Iran. Rodents captured and examined to find Leishmania species using conventional methods including direct impression smear and microscopic observation inoculation samples to Balb/c and culture in NNN medium. Also molecular method was employed to detect Leishmania in rodents by amplifying a region of the ribosomal RNA amplicon of Leishmania (ITS1-5.8S rRNA–ITS2) using Nested PCR. Leshmania species were specified by DNA sequences. 36 (38.3%) of R. opimus were Leishmania positive using at least one conventional methods. Many more ITS-rDNA fragments were amplified from R. opimus but only 65 out of 74 PCR products contained enough DNA for direct sequencing or readable sequences. The PCR assays detected in Iranian R. opimus not only Leishmania major in 59 (79.7%) rodents but also Leishmania turanica in 6 (8.1%) rodents, another parasite of the great gerbil. These parasites were found in Turkemen Sahara, North East of Iran, in a focus of rural (ZCL). L. major and L. turanica in R. opimus firmly identified from Turkemen Sahara. Nine rodents with Leishmania infections unidentified which some were unreadable sequences, these could be mixed infections of L. major, L. turanica, Leishmania gerbillisensu lato and Leishmania close to L. gerbilli or a related species reported in sandflies previously from this location. The haplotypes of L. major and L. turanica were found to be identical to that of isolates of L. major and L. turanica from Iran and in GenBank elsewhere. R. opimus is probably the key reservoir in this ZCL focus because of its abundance and its infection rates with both L. major and L. turanica.     

Multilocus microsatellite typing shows three different genetic clusters of Leishmania major in Iran

Ten polymorphic microsatellite markers were used to analyse 25 strains of Leishmania major collected from cutaneous leishmaniasis cases in different endemic areas in Iran. Nine of the markers were polymorphic, revealing 21 different genotypes. The data displayed significant microsatellite polymorphism with rare allelic heterozygosity. Bayesian statistic and distance based analyses identified three genetic clusters among the 25 strains analysed. Cluster I represented mainly strains isolated in the west and south-west of Iran, with the exception of four strains originating from central Iran. Cluster II comprised strains from the central part of Iran, and cluster III included only strains from north Iran. The geographical distribution of L. major in Iran was supported by comparing the microsatellite profiles of the 25 Iranian strains to those of 105 strains collected in 19 Asian and African countries. The Iranian clusters I and II were separated from three previously described populations comprising strains from Africa, the Middle East and Central Asia whereas cluster III grouped together with the Central Asian population. The considerable genetic variability of L. major might be related to the existence of different populations of Phlebotomus papatasi and/or to differences in reservoir host abundance in different parts of Iran.     

Leishmania major: activity of tamoxifen against experimental cutaneous leishmaniasis

Leishmaniasis is a family of diseases caused by protozoan parasites of the genus Leishmania. Various Leishmania species can cause human infection, producing a spectrum of clinical manifestations. The current treatments are unsatisfactory, and in absence of a vaccine, there is an urgent need for effective drugs to replace/supplement those currently in use. Recent studies have shown that the antineoplastic drug, tamoxifen, had direct leishmanicidal effect on several Leishmania species in vitro. Moreover, in vivo testing was carried out on some of the species and showed promising results. The authors have carried out the present work to complement previous published studies by investigating in vivo activity of tamoxifen in an experimental model of cutaneous leishmaniasis (CL) caused by Leishmania major. Groups of infected mice were given tamoxifen, orally, at a dose of 20 mg/kg/day for 15 days. Efficacy was assessed clinically, parasitologically, histopathologically by light and transmission electron microscope (TEM). Results showed that untreated infected mice suffered from autoamputation of the inoculated foot pad. However, those which received tamoxifen showed marked improvement of the cutaneous lesions and reduction of parasite burden. TEM of the cutaneous lesions from infected mice revealed the fine structure of normal Leishmania amastigotes, whereas those from infected mice treated with tamoxifen showed considerable changes. All male mice that received tamoxifen showed scrotal swelling with evident histopathological changes in the testes that could seriously compromise fertility of male mice. In conclusion, although tamoxifen causes significant side effects to the male reproductive system in the mouse model, it could provide an alternative to current agents. Results of this study demonstrated in vivo activity of tamoxifen against Leishmania major, thus, suggesting that tamoxifen is a suitable lead for the synthesis of more effective and less toxic antileishmanial derivatives.     

Organization of the lipoprotein lipase gene of red sea bream Pagrus major

Lipoprotein lipase (LPL) is a key enzyme of lipid deposition and metabolism. To investigate the mechanism of lipid deposition in fish, as a first step, we have characterized the LPL gene of a marine teleost red sea bream Pagrus major by cDNA and genomic structure analysis. The red sea bream LPL gene encodes 511 amino acids and spans approximately 6.3 kb of the genome. The coding region is organized into ten exons and nine introns. In comparison with the LPL of other animals, the deduced amino acid sequence shows a high degree of similarity with a conservation of functional domains, e.g. catalytic triad, N-glycosylation sites, lipid and heparin binding regions. The 1.1 kb of 5′ flanking region contains two CCAAT, sequences homologous to Oct-I site and response elements for hormones including glucocorticoid, insulin and thyroid hormone. The results of the present study will facilitate further study of the function and regulation of the LPL in non-mammalian vertebrates.     

昌邑海洋保护区柽柳灌丛枝干生物量估算方法

柽柳属植物(Tamarix spp.)是我国沙漠干旱地区和滨海盐渍化地区的重要树种,具有较高的生态价值。在滨海地区,柽柳是一种典型灌木,分枝多、可塑性高,以往对柽柳生物量模型的研究,多以直立枝基径和长度作为自变量,此方法虽有较高精度,但工作繁琐。因此,研究以昌邑海洋生态保护区的柽柳林为对象,分别以株高冠幅组合、冠幅为自变量,以一元线性、幂函数、二次多项式等形式建立柽柳枝干鲜重的回归方程,并进行验证比较,目的是建立准确高效且适合滨海地区的柽柳生物量估测方法。结果表明:(1)对滨海地区柽柳林,冠幅和株高是较好的测树因子,以此建立回归方程,简便易行、准确可靠,应用前景较好;(2)综合方程的准确性和稳定性,无论以冠幅株高组合,还是单以冠幅作为自变量,均确定幂函数形式的回归方程为最优,经验证与实测值的偏差分别为-2.22%和2.92%;(3)基于冠幅的方程虽预测精度稍差,但由于冠幅面积可从高分辨遥感影像上直接提取,因而有极好应用前景;(4)R2~是评价模型优劣的重要标准,但仅以此为标准并不严谨,还需结合其他验证方法;(5)测区柽柳的株高、冠幅、鲜重的均值分别为(215.2±41.4)cm,(2.49±2.21)m~2,(4.15±5.80)kg,建议通过人工管理的方式提高林分质量。     

The efficacy of a commercial β-glucan preparation, EcoActiva™, on stimulating respiratory burst activity of head-kidney macrophages from pink snapper (Pagrus auratus), Sparidae

This study investigated the in vitro effects of a commercial β-glucan preparation, EcoActiva™, on the respiratory burst activity of head-kidney macrophages isolated from pink snapper (Pagrus auratus), a marine fish cultured in Australia. Macrophages incubated with EcoActiva™ displayed morphological characteristics of activation, and were stimulated to produce superoxide. Pre-incubation with low levels of EcoActiva™ significantly increased the response to phorbol myristate acetate (PMA) and lipopolysaccharide (LPS), indicating that EcoActiva™ could prime these macrophages. Co-culturing macrophages with both LPS and PMA, or EcoActiva™ and PMA, increased burst activity compared with the response to PMA alone, however, this increase was additive and not synergistic. These results suggest that EcoActiva™ is able to stimulate non-specific immunity in snapper through increased respiratory burst activity of macrophages, an important component of the host defence network.     

Ontogeny,function and evolution of extreme floral construction inMonimiaceae

In at least 4 genera of theMonimiaceae (Tambourissa, Wilkiea, Kibara, Hennecartia) extremely specialized flowers with a hyperstigma occur, i.e. a secretory zone in the narrow entrance of the floral cup. The mucilaginous secretion of the hyperstigma and of the carpels produces a transmitting medium for pollen tubes continuous from the mouth of the floral cup to the ovules. As to their floral morphology, the two extreme types,Hortonia andTambourissa, are connected gradually by various other genera. Possible evolutionary trends and systematic problems are outlined.     

Genetic structure of Halotydeus destructor and Penthaleus major populations in Victoria (Acari: Penthaleidae)

The redlegged earth mite (Halotydeus destructor) and the blue oat mite (Penthaleus major) are major pests of pastures and crops in southern Australia. Reproductive modes, migration rates and levels of differentiation between populations were investigated using allozyme electrophoresis. Collections were made throughout Victoria and a sample was also obtained from Western Australia. Three enzyme loci were polymorphic in H. destructor (Mdh-1, Mdh-2 and Idh). Genotype frequencies of these loci did not differ between phenotypic males and females, providing no evidence for haplodiploidy. Allele frequencies were in Hardy-Weinberg equilibrium, indicating that H. destructor is diploid and sexual. This was confirmed via crosses between males and females. Allele frequencies differed between Victorian sites, although F statistics indicated little differentiation over all loci. A sample from Western Australia did not differ in allele frequencies from the Victorian sites. Four polymorphic loci were found in P. major (Mdh-1, Mdh-2, Idh and Gpi). Only a few multilocus genotypes occurred in a sample, indicating that P. major is parthenogenic. No male P. major were found in this study. A number of colour morphs were also identified and a genetic association between genital plate colour and clonal type was found in one population of P. major. Two different body colour morphs were associated with different clonal types.     

Effects of rhizosphere soil,vesicular-arbuscular mycorrhizal fungi and phosphate onPlantago major L. ssp.pleiosperma Pilger

Biotic factors in the rhizosphere and their effect on the growth ofPlantago major L. ssp.pleiosperma Pilger (Great plantain) were studied. In a pot experiment the effect on shoot growth of the addition of 2.5% rhizosphere soil at four levels of phosphate was highly dependent on the availability of phosphate: a promoting effect at low phosphate levels was observed while a reducing effect occurred at higher phosphate levels. As the roots were infected with vesicular-arbuscular mycorrhizal (VAM) fungi in the treatment with rhizosphere soil, two other experiments were set up to separate effects of the indigenous VAM fungi from effects of the total rhizosphere population. The uptake of phosphate and shoot growth was not decreased at higher phosphate availability when VAM inoculum was added alone or in combination with rhizosphere soil. The growth reducing effect of the rhizosphere soil could therefore not be ascribed only to mycorrhizal infection. The results suggest that biotic factors in the rhizosphere soil affect the phosphate uptake ofPlantago major ssp.pleiosperma. This may, under conditions of phosphate limitation, lead to an increase of phosphate stress and, subsequently, a growth reduction. Futhermore, it is concluded that VAM fungi, as part of the rhizosphere population, may compensate this phosphate stress by enhancing the phosphate uptake.Grassland Species Research Group Publication No. 148.     

A new species of Hemicyclops (Copepoda, Poecilostomatoida) from burrows of the mud shrimp Upogebia major in an estuarine mud-flat in Tokyo Bay, Japan

A new species of poecilostomatoid copepod, Hemicyclops tanakai n. sp. was collected from burrows of the mud shrimp Upogebia major in an estuarine mud-flat in Tokyo Bay. The new species can be distinguished from its congeners by combination of the following characteristics: setation of the antennule, the segmentation of the antennule, the length–width ratio of the caudal ramus, the ornamentation on the third segment of antenna and the shape of the genital double somite.     

Ammonium and nitrate nutrition inPlantago lanceolata L. andPlantago major L. ssp.major

With the aims (1) to test whether the different natural occurrence of twoPlantago species in grasslands is explained by a different preference of the species for nitrate or ammonium; (2) to test whether the different occurrence is explained by differences in the flexibility of the species towards changes in the nitrogen form; (3) to find suitable parameters as a tool to study ammonium and nitrate utilization of these species at the natural sites in grasslands, plants ofPlantago lanceolata andP. major ssp.major were grown with an abundant supply of nitrate, ammonium or nitrate+ammonium as the nitrogen source (0.5 mM). The combination of ammonium and nitrate gave a slightly higher final plant weight than nitrate or ammonium alone. Ammonium lowered the shoot to root ratio inP. major. Uptake of nitrate per g root was faster than that of ammonium, but from the mixed source ammonium and nitrate were taken up at the same rate. In vivo nitrate reductase activity (NRA) was present in both shoot and roots of plants receiving nitrate. When ammonium was applied in addition to nitrate, NRA of the shoot was not affected, but in the root the activity decreased. Thus, a larger proportion of total NRA was present in the shoot than with nitrate alone. In vitro glutamate dehydrogenase activity (GDHA) was enhanced by ammonium, both in the shoot and in the roots.In vitro glutamine synthetase activity (GSA) was highest in roots of plants receiving ammonium. Both GDHA and GSA were higher inP. lanceolata than inP. major. The concentration of ammonium in the roots increased with ammonium, but it did not accumulate in the shoot. The concentration of amino acids in the roots was also enhanced by ammonium. Protein concentration was not affected by the form of nitrogen. Nitrate accumulated in both the shoot and the roots of nitrate grown plants. When nitrate in the solution was replaced by ammonium, the nitrate concentration in the roots decreased rapidly. It also decreased in the shoot, but slowly. It is concluded that the nitrogen metabolism of the twoPlantago species shows a similar response to a change in the form of the nitrogen source, and that differences in natural occurrence of these species are not related to a differential adaptation of nitrogen metabolism towards the nitrogen form. Suitable parameters for establishing the nitrogen source in the field are thein vivo NRA, nitrate concentrations in tissues and xylem exudate, and the fraction of total reduced nitrogen in the roots that is in the soluble form, and to some extent thein vitro GDHA and GSA of the roots. Grassland Species Research Group. Publ. no 118.     

Light and electron microscopic study on the endocrine cells of the pancreas in a marine teleost,Fugu rubripes rubripes

Summary The pancreatic endocrine tissue of Fugu rubripes rubripes consists of numerous round principal islets (Brockmann bodies) of various sizes scattered around the gall-bladder. The endocrine cells are divided into A-, B-, D-, and F_f-cells. Each cell type was identified by comparing thick and thin sections in both light and electron microscopy. Aldehyde-fuchsin positive B-cells contain numerous round secretory granules (average diameter 300 nm) each of which has a round compact core of moderate density; a narrow space exists between this core and the limiting membrane. Grimelius' silver positive A cells contain round secretory granules (average diameter 360 nm) with a hexagonal or tetragonal crystalline core (average diameter 170 nm) of high density; the silver grains preferentially appear in the space between the limiting membrane and the core. The crystalline core of each -granule often contains an appendix-like structure of variable shape. D cells blackened by the silver impregnation method of Hellman and Hellerström (1960) have round secretory granules (average diameter 320 nm) filled with a flocculent material of low density. The fourth cell type (F_f-cell) has a clear cytoplasm after differential staining for light microscopy. By electron microscopy, this cell has elongated fusiform secretory granules (520 nm average length × 230 nm average width) filled with numerous filaments arranged in parallel with the longitudinal axis. Figures suggesting granule formation in the sacs of the Golgi apparatus were obtained in all of islet cell types. Equivalents of emiocytotic release of secretory granules were encountered in the A and F_f cells.     

The effect of tunicamycin on the protease activity of GP63 from Leishmania major

The protease activity of gp63 from L. major was studied in relation to tunicamycin induced N-deglycosylation. It was found that after tunicamycin treatment, a N-deglycosylated product of gp63 with protease activity is present at the cell surface of Leishmania promastigote.     

High toxicity of the novel bloom-forming species Chattonella ovata (Raphidophyceae) to cultured fish

A toxicological study of an axenic cell line of novel species Chattonella ovata Y. Hara et Chihara (Raphidophyceae) revealed that cultured species of sea bream (Pagrus major), horse mackerel (Trachurus japonicus), and yellowtail (Seriola quinqueradiata) were killed by 4.1–6.8 × 10³, 5.4 × 10³, and 2.8 × 10³ cells/mL, respectively. The sensitivity of the gill lamellae to C. ovata differed among the fish species tested. This finding revealed that C. ovata was highly toxic to the cultured fish. Histological examination showed that edema and hyperplasia of the secondary gill lamellae of red sea bream and horse mackerel occurred when exposed to, or killed by C. ovata, whereas severe damage in the gill lamellae was not observed in yellowtail. Chattonella produced high amounts of superoxide anion radicals and hydrogen peroxide, possibly responsible for the fish death observed. Based on the results of this study and occurrence of a red tide by this organism in China in 2001, we consider this organism to be one of the harmful algae in coastal waters. This is the first report demonstrating that C. ovata is highly toxic to fish, and that it produces superoxide and hydrogen peroxide.     

Needle area measurement by the cut method and estimation of specific leaf area inCryptomeria japonica

Needle surface area inCryptomeria japonica was measured using a newly proposed cut method. Sample needles of various lengths were taken from foliage shoots belonging to various height layers of nine trees growing at three sites. Needles were cut into small pieces with a hand-made cutter made of razor blades and washers. By measuring the circumference and thickness of each piece, its lateral area was calculated and summed to give the total surface area of the needle. For estimating the surface area of a needle (s), two linear parameters of needle size termedy _n* and /were proposed:y _n* was the distance between the needle tip and the uppermost point of attachment of the needle to the shoot, whilel was the distance between the needle tip and the lowermost point of attachment. The power-form relationship betweens andl was superior to thes-y _n* relationship, since the former did not differ significantly among shoots of different diameter. Based on thes-l relationship, the total surface area of a shoot was estimated from thel-census of the shoot. Specific leaf area of a shoot (SLA), defined as half of the shoot surface area divided by the dry weight of the shoot, decreased from 90 to 3 [cm²g(dry wt)⁻¹] with the diameter of the woody tissue of the foliage shoot.