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31.
This study investigated variation in the rates of growth and mortality, and age and fork‐length (LF) compositions of two exploited species of Mugilidae, Liza argentea and Myxus elongatus, in two south‐east Australian estuaries (Lake Macquarie and St Georges Basin). An ageing protocol was developed by counting opaque growth zones on sectioned otoliths which was validated by periodically examining the otoliths of captive‐reared young‐of‐the‐year fishes, and marginal increment analysis of wild fishes. The maximum recorded age was 17 years for L. argentea and 12 years for M. elongatus, which is greater than generally observed in other species of mugilids. Growth models of each species significantly differed between sexes and, except for male L. argentea, between estuaries. Fishes from Lake Macquarie generally had a greater mean LF at age than those from St Georges Basin and females of both species generally attained a greater maximum LF and age than males. Gillnet catches of L. argentea were of similar LF and age compositions in both estuaries, whereas the age composition of catches of M. elongatus in Lake Macquarie contained a greater proportion of younger fish. Estimates of total, natural and fishing mortality were greater for M. elongatus than L. argentea across both estuaries, and estimates of total mortality were greatest for both species in Lake Macquarie. The data indicate that neither species has been overfished in these estuaries. 相似文献
32.
The effect of time of stocking on the extent and source of mortality in 0+ year pike Esox lucius was investigated in a lake (20 ha) and a drainable pond (0·5 ha) using pike with alizarin marked otoliths. The results indicated that pike stocked late relative to the recruitment of native 0+ year pike fell victim to cannibalism from these larger individuals. This resulted in very low survival through the first growing season (<2%). Pike stocked early in the season exhibited significantly higher survival (>12%). Analyses of the size distribution of the alizarin marks from these fish revealed that the largest 0+ year pike exhibited by a factor of 3·3, higher survival than the average 0+ year pike in the lake. In order for large 0+ year pike to exhibit such high relative fitness a minimum of 69·7% of the original population must suffer size dependent mortality. In the pond the survival of the largest pike was by a factor of 4·2 higher than the average pike, and the corresponding size dependent mortality was 76·4%. The substantial size‐dependent mortality was most probably due to intra‐cohort cannibalism or habitat segregation between large and small 0+ year pike that exposes the small pike to predatory fishes in the open lake. Cannibalism exerts a major influence on the survival of 0+ year pike post‐stocking although the magnitude and origin differ in relation to stocking time. 相似文献
33.
Chromosome doubling was induced in vitro in a diploid hybrid of Rosa rugosa Thunb. using oryzalin as the spindle inhibitor. Nodal sections, 2 mm long, were exposed to 2.5 or 5 μM oryzalin and 10 mm
nodal sections were exposed to 5 μM oryzalin for 0 (controls), 6, 12, 24 and 48 h. The ploidy of the emergent shoots was determined
by flow cytometry. The frequency of tetraploid and mixoploid leaves that developed from 2 mm nodal sections exposed to 5 μM
oryzalin peaked at 12 h exposure, when 35% of the leaves were tetraploid, but fell after longer exposures. Fewer tetraploid
and mixoploid leaves were found when 2 mm nodes were exposed to 2.5 μM oryzalin for 6 and 12 h, indicating that it took longer
for a spindle inhibiting concentration of oryzalin to build up in the meristem. However, the frequencies of tetraploid and
mixoploid leaves continued to rise after 12 h and were highest at 48 h, when 44% were tetraploid. In treatments with 5 μM
oryzalin, the frequencies of tetraploid and mixoploid leaves were lower, at equivalent exposure times, in 10 mm nodes than
2 mm nodes. This suggests that oryzalin diffused to the meristem mainly via the cut surfaces and that access via the epidermis
and cuticle was impeded. 相似文献
34.
Mineralization process during acellular cementogenesis in rat molars: a histochemical and immunohistochemical study using fresh-frozen sections 总被引:2,自引:2,他引:0
Yamamoto T Domon T Takahashi S Anjuman KA Fukushima C Wakita M 《Histochemistry and cell biology》2007,127(3):303-311
This study was designed to detect tissue non-specific alkaline phosphatase (TNSALP) by Azo-dye staining, calcium by glyoxal
bis (2-hydroxyanil) (GBHA) staining, bone sialoprotein (BSP) and osteopontin (OPN) by immunoperoxidase staining in developing
rat molars, and also to discuss the mineralization process during acellular cementogenesis. To restrain a reduction in histochemical
and immunohistochemical reactions, fresh-frozen undemineralized sections were prepared. Where the epithelial sheath was intact,
TNSALP reaction was observed in the dental follicle, but not in the epithelial sheath. With the onset of dentin mineralization,
the BSP- and OPN-immunoreactive, initial cementum layer appeared. At this point, cementoblasts had shown intense TNSALP reaction
and GBHA reactive particles (=calcium-GBHA complex) appeared on the root surface. With further development, the reaction of
TNSALP and GBHA became weak on the root surface. Previous studies have shown that the initial cementum is fibril-poor and
that matrix vesicles and calciferous spherules appear on the root surface only during the initial cementogenesis. The findings
mentioned above suggest that: during the initial cementogenesis, cementoblasts release matrix vesicles which result in calciferous
spherules, corresponding to the GBHA reactive particles. The calciferous spherules trigger the mineralization of the initial
cementum. After principal fiber attachment, mineralization advances along collagen fibrils without matrix vesicles. 相似文献
35.
Variation in habitat use along the freshwater–marine continuum by grey mullet Mugil cephalus at the southern limits of its distribution
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In this study, habitat use by Mugil cephalus was investigated in the waters of the west coast of the North Island of New Zealand by analysing microchemical composition of otoliths (laser‐ablation inductively coupled plasma mass spectrometry) obtained from individuals from commercial fish stocks and research surveys. Results of this study show that M. cephalus at the southern limits of its distribution display highly flexible migratory behaviour with extensive use of freshwater and brackish habitats, potentially enabling them to maximize foraging opportunities. Mugil cephalus can tolerate a wide range of salinities and can therefore utilize higher productivity areas, such as estuaries and eutrophic riverine lakes. Finally, M. cephalus populations across a range of climates and latitudes appear to differ in the extent to which they utilize freshwater and brackish habitats, possibly with increasing penetration of fresh waters with increasing latitude. 相似文献
36.
Validation of daily increments and a marine‐entry check in the otoliths of sockeye salmon Oncorhynchus nerka post‐smolts
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C. Freshwater M. Trudel T. D. Beacham C.‐E. Neville S. Tucker F. Juanes 《Journal of fish biology》2015,87(1):169-178
Juvenile sockeye salmon Oncorhynchus nerka that were reared and smolted in laboratory conditions were found to produce otolith daily increments, as well as a consistently visible marine‐entry check formed during their transition to salt water. Field‐collected O. nerka post‐smolts of an equivalent age also displayed visible checks; however, microchemistry estimates of marine‐entry date using Sr:Ca ratios differed from visual estimates by c. 9 days suggesting that microstructural and microchemical processes occur on different time scales. 相似文献
37.
Utah chub Gila atraria , a temperate freshwater minnow, formed valid otolith annuli (annual growth rings), even when raised in a constant‐temperature desert spring environment. This suggests that factors other than seasonal variation in water temperature control annual otolith marking. 相似文献
38.
The effects of starvation on daily growth and increment formation in the otolith were examined using a double oxytetracycline-labelling method on larval milkfish, Chanos chanos (Forsskål), reared under different feeding regimes. The results indicated that the differences in body and otolith growth between the larvae fed once and three times a day were not significant, and that the otolith growth increment was deposited daily in both groups of fed larvae. In contrast, the starved larvae grew at a slower rate than fed larvae in body length and otolith dimensions, and the otolith growth increment in the starved larvae was not deposited on a daily basis. After undergoing starvation, the larvae were unable to recover their normal growth either in otolith increment deposition or in body and otolith growth even though they were fed. Therefore, the application of ageing techniques based on counting otolith growth increments seems to be inaccurate for starved larvae. 相似文献
39.
K.?A.?Pickens Z.?M.?ChengEmail author R.?N.?Trigiano 《In vitro cellular & developmental biology. Plant》2005,41(6):770-774
Summary Protocols for both axillary bud proliferation and shoot organogenesis of Euphorbia pulchurrima Winter RoseTM were developed using terminal buds and leaf tissues. Greenhouse-grown terminal buds were placed on Murashige-Skoog (MS) basal
medium supplemented with various concentrations of either benzlyaminopurine (BA) or thidiazuron (TDZ). Explants produced the
greatest number of axillary buds on media containing between 2.2 and 8.8 μM BA. The number of explants that produced axillary buds increased with increasing BA concentration. TDZ at concentrations
between 2.3 and 23.0 μM caused hyperhydricity of shoots and were not effective in promoting shoot proliferation. The most calluses and shoots were
produced from leaf midvein sections from in vitro grown plants placed on the medium containing 8.8–13.3 μM BA and 17.1 μM indole-3-acetic acid (IAA) for 1 mo. before transferring to the medium containing only BA. Adventitious buds were produced
only from red-pigmented callus, and explants that produced callus continued to produce adventitious shoots in the presence
of IAA. Five-mo.-old shoots derived from shoot culture or organogenesis rooted readily in artificial soil with or without
treatment with indolebutyric acid, and were acclimatized in the greenhouse. 相似文献
40.
Rosa?M.?Pérez-Clemente Amparo?Pérez-Sanjuán Lorenzo?García-Férriz José-Pío?Beltrán Luis?A.?Ca?asEmail author 《Molecular breeding : new strategies in plant improvement》2005,14(4):419-427
The main obstacle to genetic engineering of fruit tree species is the regeneration of transformed plantlets. Transformation events in peach (Prunus persica L.) have been reported using particle bombardment or Agrobacteriummediated transformation of immature embryos. However, the regeneration of plants from transgenic tissues is still difficult and the recovery of non-chimeric plants has not been reported to date. In this paper we describe an efficient, reliable transformation and regeneration system to produce transgenic peach plants using embryo sections of mature seeds as starting material. This represents an important advantage due to the availability of such material throughout the year. A. tumefaciens strain C58 (pMP90) containing the binary plasmid pBin19 was used as vector system for transformation. We used the Nospro-nptII-Noster cassette as a selectable marker and the CaMV35Spro-sgfp-CaMV35Ster cassette as a vital reporter gene coding for an improved version of the green fluorescent protein (sGFP). In vitro cultured embryo sections were Agrobacterium-cocultivated and, after selection, transgenic shoots were regenerated. Shoots that survived exhibited high-level of sGFP expression mainly visible in the young leaves of the apex. In vivo monitoring of GFP expression permitted an early, rapid and easy discrimination of both transgenic and escape buds. After elimination of escapes, transgenic shoots were rooted in vitro and the recovered plantlets were screened using PCR amplification. Southern analysis confirmed stable genomic integration of the sgfp transgene. The high levels of GFP expression were also maintained in the second generation of transgenic peach plants. 相似文献