The mechanism of energy allocation over reproduction and somatic growth in female North Sea plaice,Pleuronectes platessa L.

The mechanism of surplus production allocation over reproduction and somatic growth was studied in female plaice using market sampling data, tagging data and a tank experiment. Somatic growth peaked between March and October and main gonad growth occurred between October and January. However, an estimated 50% of the gonad growth was subsidized from body reserves built up during the growing period. Therefore processes of somatic growth and the building up of energy reserves for gonad growth take place simultaneously.Market sampling data and a tank experiment showed that pre-spawning energy reserves were positively correlated with somatic growth but also indicated that a twofold increase in somatic growth only results in an increase in energy reserves of less than 10%. Analysis of the relation between back-calculated somatic growth and reproductive investment in individual females did not reveal a significant effect of somatic growth on size-specific fecundity, gonad weight and pre-spawning body weight. It is concluded that size-specific reproductive investment is not, or only slightly, enhanced by an increase in surplus production. In the tank experiment females, which did not grow by more than 20% of the initial body weight, did not develop their gonads, but this phenomenon of skipping a spawning season does not seem to occur in the North Sea population.The results of this study are summarized in a hypothetical model of the mechanism of surplus production allocation that is based on physiology and can be tested with tank experiments. The model postulates that surplus production is used to maintain body energy reserves at a threshold level that increases from a post-spawning low to a pre-spawning high. Surplus production exceeding the demands for maintaining body energy reserves at the threshold level is channeled into somatic growth. Implications of the mechanism for the changes in biological parameters in relation to reproductive strategies are discussed.     

Immigration of larval plaice (Pleuronectes platessa L.) into the western wadden sea: A question of timing

Migration of larval plaice into a nursery area in the western Wadden Sea was monitored during three immigration seasons. Daily otolith increments were used to estimate age and hatch dates of the larvae, and the hatch dates were compared to egg-production curves. Different cohorts of larvae invaded the area, originating from different spawning grounds. During a cold year, most larvae probably came from the Western Channel, but during the two warm years most larvae originated from more northern spawning grounds. Settlement on a tidal flat showed a delayed response to immigration in the first part of the season, but a direct response later in the season. Length-frequency distributions of settled juveniles were compared to expected frequencies based on a simple growth model. It is argued that early in the season growth-related mortality may have been too high to ensure successful settlement, and that timing could be of significant importance for larval immigration to be successful.     

Variations in settlement and growth of 0-group plaice (Pleuronectes platessa L.) in the dutch wadden sea as determined by otolith microstructure analysis

Larval growth, date of settlement, and subsequent growth of 0-group plaice were compared in the eastern (Dollard) and western (Texel) parts of the Dutch Wadden Sea in autumn 1988. Daily increment analysis in otoliths with SEM showed that specimens sampled in the Texel region, and at 2 Dollard stations, hatched early in the season, had a shorter larval period (50 to 61 d) with high growth rates, and early settlement. All specimens caught at the other 6 stations hatched later, had a long larval phase (62 to 82 d) and settled later in the season.Estimates of maximum growth based on optimal feeding conditions and the prevailing water temperatures in both tidal basins were compared to the growth rates observed in the field. According to previous studies, plaice in the Texel region have optimal growth. All late settlers in the Dollard and part of the early settlers also had optimal growth. However, some early settlers in the Dollard had significantly lower growth rates than the batch of synchronously settled specimens from the Texel region.     

Mortality rates of 0-group plaice (Pleuronectes platessa L.), dab (Limanda limanda L.) and turbot (Scophthalmus maximus L.) in European waters: I. Statistical analysis of the data and estimation of parameters

The early demersal phase of those species of flatfish with inshore nursery areas are usually accessible with relatively modest demands on gear and logistics. However, the design of the sampling programme, adjustment for gear efficiency, and statistical analysis of the resulting catch data, raise a number of questions which have not hitherto been addressed comprehensively.This paper presents a systematic analysis of all the published data known to us of demersal 0-group flatfish in nursery grounds adjacent to the North Sea and British coastal waters, together with some hitherto unpublished data. The analysis showed that in most cases catches from repeated tows of a beam trawl can be averaged, after appropriate correction for gear efficiency, to give representative estimates of fish density for a succession of sampling dates.From the time series of density estimates thus obtained a selection of the period from maximum density until the early part of the following year proved to give a consistent window for the estimation of mortality rates by use of regression methods. A total of 57 data sets was analysed (45 plaice, 11 dab and 1 turbot). Of these 48 gave essentially linear log/time trends, of which 7 showed some degree of curvature, (4 concave upwards and 3 concave downwards). In one further case the trend remained essentially horizontal (flat-topped) until near the end of the sampling window and then declined sharply. The remaining 8 trends were so erratic as to preclude any further conclusions to be drawn. There was no obvious regularity in the occurrence of either the concave or flat-topped patterns by location or in time.Estimates of density and mortality rate are presented, together with estimates of standard errors of these estimates. The interpretation of these estimates in relation to the design and frequency of the sampling procedure is discussed, with special reference to the different topographies of the areas surveyed.     

Seasonal distribution of young sole (Solea solea (L.)) in the nursery ground of the bay of Vilaine (Northern bay of Biscay)

The distribution of young sole was studied in the bay of Vilaine nursery ground as a function of age and season for the 0, 1 and 2-groups. During 1988 and 1989, bimonthly trawl surveys were carried out from the estuary to the 50-m-isobath along a 65-km transect. A regular seasonal pattern demonstrated two combined trends. An offshore movement is observed with increasing age; this general trend is marked by an inshore migration in spring and an offshore one in winter. The fluctuations of the distribution pattern are discussed in relation to sedimentary characteristics, to trophic requirements and to hydroclimatic variations. The main conclusion is that young soles are concentrated inside a closed nursery area. In their third winter some participate in spawning migration and they get mixed, to a certain extent, with newly recruted soles from nearby nursery grounds.     

The influence of environmental conditions on settlement,distribution and growth of 0-group sole (Solea solea (L.)) in a macrotidal estuary (Vilaine,France)

In the Vilaine estuary, the environmental conditions at the onset of the settlement of metamorphosing sole have been surveyed for 5 years. The inshore migration occurs either in early or in late April depending on the hydroclimatic conditions: sole are observed in the estuary when bottom water salinity varies between 25 and 30 S and water temperature is up to 11°C. During spring, their distribution pattern is similar in all years: first, accumulation at the entrance of the estuary, then concentration in the upper parts and finally, colonization of the whole estuarine area by juveniles. Interannual variations in growth rates were observed during their first estuarine phase, in particular when the estuary is transformed into a ‘ria’ with high water temperature and salinity. These biological features are discussed according to ontogenic changes occurring during these early life stages. From field and experimental data and from literature information on sole and other pleuronectiform species, a conceptual model on relationships between environmental parameters and metamorphosis processes in estuarine areas is proposed.     

Distribution of flatfish eggs in the 1989 egg surveys in the southeastern North Sea,and mortality of plaice and sole eggs

From January to July 1989 eight egg surveys were carried out in the southeastern North Sea. The first three surveys were designed to estimate the egg production of plaice (Pleuronectes platessa) and cod (Gadus morhua). The other five surveys were aimed at the eggs of sole (Solea solea) and horse mackerel (Trachurus trachurus) Of a selection of the samples collected in 1989 all fish eggs were identified to species. This paper presents data on the distribution, timing and intensity of spawning of the flatfish species plaice, flounder (Platichthys flesus), dab (Limanda limanda), long rough dab (Hippoglossoides platessoides), sole, solenette (Buglossidium luteum), turbot (Scophthalmus maximus) and scaldfish (Arnoglossus laterna).Egg mortality was studied in plaice and sole and compared to previous estimates. Plaice egg mortality in 1988 and 1989 was higher than in 1987, coinciding with higher ambient temperatures. Egg production in sole was recorded earlier in the year in 1988 to 1990 than in 1984, and at lower ambient temperatures. Sole egg mortality rates were shown to be lower in 1988 to 1990 than in 1984.     

On selective tidal transport in the migration of North Sea Plaice (pleuronectes platessa) and other flatfish species

Evidence is given for selective tidal transport in North Sea plaice and other flatfish species. Data collected during midwater plankton surveys in two Dutch Wadden Sea inlets in early spring in the years 1970 to 1977 show that plaice, sole, flounder and dab demonstrate pelagic swimming behaviour in that period. Plaice, sole and flounder show a clear selective tidal transport mechanism to re-enter the Wadden Sea after staying in the open sea in winter whereas dab tends to leave the Wadden Sea. Data on by-catches of semi-pelagic pair trawl fishery for gadoids in the Dutch coastal area show that small quantities of plaice may be caught off the bottom throughout the whole year whereas sole moves to higher levels in two distinct periods only. The first period lower left diagram) demonstrate a strong preference for northgoing currents. This is also the direction towards the areas from which the plaice used had been transported to the laboratory and therefore this preference for northgoing tides might be interpreted as a clear case of homing to the Silverpits and Borkum areas.Also the rate of dispersion of the cluster of displaced tagged plaice in general (Fig. 18, lower right diagram) is much faster in the first months after release than that of the local plaice. Thus displaced plaice are more strongly motivated to migrate than non-displaced fish. This may well have been the case too in the plaice equiped with the transponding acoustic tags. This together with the release in an area with strong currents and narrow tidal ellipses means that the plaice should be considered to have been in an exceptional situation, extremely suited for travelling at great speeds in a fixed direction. Fig. 18 also shows the average surface tidal current velocities, derived from the 13 maps with hourly data on water circulation in the Stroomatlas Nederland (1963). It is obvious that the Lowestoft plaice, mostly released nearer to the coast within the release area, encountered the highest average current velocities observed in the North Sea. It cannot be proven that these circumstances explain completely the vast speed of the Lowestoft plaice but it certainly demonstrates that there is a bias in these experiments which could easily affect the results. When drawing conclusions in respect to the “normal” picture of plaice migration this bias should not be ignored.In the common sole selective tidal transport is observed in juveniles when entering the Wadden Sea in spring. In adult soles this mechanism is a common feature in March to May during the spawning migration but no evidence for the use of this mechanism is available during other periods of the year. The sole thus is an example of a flatfish species using selective tidal transport in a restricted period and for special purposes only.In plaice the use of selective tidal transport in the Wadden Sea inlets has been shown for juveniles. In adult plaice the need for using the mechanism might be much less although plaice have been seen swimming at the surface in spring (van den Ende, 1849) during day time quite in contrast with their normal behaviour. In spring nights, among soles swimming at the surface, plaice too have been observed (together with some dabs and turbots) but in much lower numbers than the sole (de Veen, 1967).On the whole there is not much evidence for a strong continuous use of selective tidal migration in plaice. No serious drops in the catch rates during specific tidal phases in the bottom trawl fisheries have been recorded by the results of the UK 81 otter trawl fishery. The coincides with the re-entering of soles in the Wadden Sea and with the well-known phenomenon of soles swimming at the surface. During this period the soles use selective tidal transport to reach the spawning grounds near the continental coasts.Data on catch per unit effort of a Dutch ottertrawler in 1958 to 1960, constantly fishing in one restricted area near Terschellingerbank lightvessel, reveal significant differences between day and night catch rates and a change from a preference for flood tide in the first half of the year to a preference for ebb tide in the second half.The available evidence for selective tidal transport in plaice is discussed in relation to the patterns of migration in 4 plaice sub-stocks studied by means of tagging experiments, and in relation to results of displacement experiments with mature and immature plaice. The tagging and displacement experiments present a picture of migration in which the directional swimming is a weak component superimposed on largely random movements and the speeds of travelling are low. The plaice react to displacement by trying to return to their original grounds and this tendency to home lasts for a full year.This picture about selective tidal transport contrasts with results obtained by the Lowestoft Laboratory. Plaice equiped with transponding acoustic tags did show largely directed and fast tidal migration before and after spawning. Arguments are given that these plaice were, however, in an exceptional position and may have shown homing behaviour. Notwithstanding this reservation to the Lowestoft experiments, these results and the present ones are explained if it is assumed that apparently only a fraction of the population uses the mechanism of selective tidal migration, thus saving energy and achieving quick transport when necessary. It is likely that in plaice as in sole the mechanism will be used in special cases only, probably for short periods, in certain areas.     

Organochlorines in benthic polychaetes (Nephtys Spp.) and sediments from the southern North Sea. identification of individual PCB components

ΣPCB concentrations (as the sum of concentrations of 35 individual components) on a lipid basis varied more than an order of magnitude between samples of polychaete worms (Nephtys spp.) from different stations in the southern North Sea. PCB patterns, i.e. the relative contribution of each component to ΣPCB, were highly similar for the larger part of the area.The geographical differences between concentrations of PCB's reflected the general routes of residual water and suspended particulate matter transport throughout the North Sea. The Rhine is likely to be the main source for PCB's in Dutch coastal waters, including the entire coastline formed by the Dutch Wadden Sea islands. Theoretical patterns of PCB's in solution were calculated from the PCB patterns in Nepthys and values of bioconcentration factors reported.Concentrations of HCB, α- and γ-HCH, dieldrin, p,p′-DDD and p,p′-DDT were at least an order of magnitude lower and close to, or even below, detection limit in most samples. Although concentrations of α-and γ-HCH in solution were the highest of the compounds investigated, their concentrations in Nephtys were among the lowest, which might have been due to their relatively high solubility in water, or metabolism to more polar derivatives.Based on total sediment analyses, organochlorine concentrations in Nephtys spp. were not correlated with the concentrations in the (type of) sediment which they inhabited. In sediments the fraction of grains <63 μm appeared to be very important.A sewer outlet near Grimsby (U.K.) was found to be a source for HCB and Σ-DDT.     

南疆海岛棉和陆地棉棉铃发育过程中的生理生化特征

在大田条件下,以南疆主栽海岛棉和陆地棉为材料,研究棉铃发育过程中棉铃各部位的生理生化特征。结果表明,海岛棉铃壳叶绿素a、叶绿素b含量极显著高于陆地棉,类胡萝卜素含量极显著低于陆地棉。海岛棉铃壳、种子、纤维中可溶性蛋白质含量、过氧化氢酶活性和抗坏血酸含量明显高于陆地棉,且纤维中过氧化物酶活性也高于陆地棉,铃壳中丙二醛含量低于陆地棉。海岛棉与陆地棉发育棉铃各部位生理生化的异质性是棉铃铃期、铃重、衣分和纤维长度、伸长率、比强度等种间差异的内在表现。     

不同采割时间下白洋淀菹草的营养成分变化分析

[目的]为了研究确定菹草（Potamogeton crispus L.）的最适采割时间,[方法]笔者在2009年4月21日至6月1日期间在河北省白洋淀鸭子坑南坡、虎皮淀、老虎口三个定点水域每隔一周连续采割了7批菹草鲜样,将每个水域菹草经脱水处理后,按照饲料分析方法分别测定了其营养成分值。[结果]4月21日至5月12日期间采割的菹草样品中粗蛋白质、粗脂肪含量显著高于后期采割的样品(P<0.05);5月19日至6月1日期间采割的菹草粗灰分和钙含量显著高于采割前期的样品（P<0.05）,且总磷含量显著低于前期菹草样品（P<0.05）。变异系数统计表明,随菹草生长期的延长,营养成分变异由大到小依次为：钙、磷、粗蛋白质、粗脂肪、灰分、粗纤维、无氮浸出物。[结论]总之,在4月中旬至5月中旬生长期内白洋淀菹草营养价值最高,最适宜采割,其饲用价值仍有待通过开展饲养试验来进行确证。     

沙棘3-磷酸甘油脱氢酶基因生物信息学及表达分析

沙棘果肉和种子组织中均富含生物活性油。3-磷酸甘油脱氢酶(GPD1)是促进油脂合成前体甘油-3-磷酸(G3P)合成的限速酶。本研究对沙棘HrGPD1基因进行生物信息学分析(氨基酸序列,保守域,亚细胞定位等),及其在沙棘不同组织(果肉和种子)中的表达情况。研究发现:HrGPD1开放阅读框为1 143 bp,编码380个氨基酸,无信号肽和跨膜结构域,存在多个磷酸化位点,定位于质体中,蛋白高级结构以α-螺旋为主,该蛋白序列与桑、梅、烟草和拟南芥的GPD表现出较高的序列相似性。qRT-PCR分析发现,HrGPD1基因在沙棘品系‘新俄3号’成熟种子和果肉中的相对表达量分别为0.52和1.35,与二者的含油率高低规律相一致。这为进一步研究HrGPD1基因在沙棘生物活性油合成过程中的作用机理提供科学依据。     

Interspecific hybridization between Vicia faba (L.) and Vicia narbonensis (L.): Early pod growth and embryo-sac development

Summary Fertilized embryo-sac development and pod growth was studied in one Vicia faba cultivar, one Vicia narbonensis population and their reciprocal crosses. The initial development of endosperm and embryo was at least four days faster in V. narbonensis than in V. faba. Pods and ovules developed also faster in V. narbonensis than in V. faba. The growth rate of the hybrid pods followed the growth rate of the mother species, but was slower than that of the pods from selfed flowers. In the cross V. narbonensis × V. faba the ovules stopped growing 9 days after pollination, while in the reciprocal cross they stopped growing 15 days after pollination. Hybrid embryo-sacs from V. faba × V. narbonensis were aborted before they reached the stage of 256 endosperm nuclei or 200 embryo cells. Selfed V. faba embryo-sacs reached this stage in less than 9 days after pollination. In the reciprocal cross the embryo-sacs were aborted before they reached the stage of 128 endosperm nuclei or 80 embryo cells. Selfed V. narbonensis embryo-sacs reached this stage at the 4th day after pollination. Given that at these stages the embryo has less than 200 cells it was concluded that an in-ovule embryo culture technique should be developed to obtain hybrid plants.     

Germination of pollen of weed rye (Secale segetale L.) on wheat (Triticum aestivum L.) stigmas and the growth of the pollen tubes

Summary Two gene pairs have been found regulating the crossability of wheat and rye. It is concluded from our work that the same genes regulate crossability between wheat and weed rye. The crossing barrier was not observed in the stigma, style or ovary wall because pollen tubes of weed rye were seen in these tissues irrespective of the wheat variety used as the female parent.Pollen grains germinated within 6 min after pollination. The tubes reached the region of the micropyle after about 40 min.     

Genetic diversity of the `peruvianum-complex' (Lycopersicon peruvianum (L.) Mill. and L. chilense Dun.) revealed by RAPD analysis

Two lines of hexaploid wheat were crossed and the basic generations of parent, F1, F2 and back-cross were sown in a controlled-environment chamber. FreshF1 and back-cross grains were generated, so the material could be handled either as the standard set of basic generations on a whole-plant basis, or as an extended set on an embryo or endosperm basis. The experiment was repeated. Mature grains were harvested and the starch particle size distribution was analysed in 3284 grains from 111 plants. Means and variances were partitioned into additive, dominance and interaction components. Grains from cross-pollinations had B-granule contents between parental values, rather than of the maternal parent, indicating an involvement of the grain genotype. Quantitative models based on endosperm genotype gave a better fit to the data than those based on embryo genotype. The difference in starch B-granule content between the parents was largely due to additive genes. Dominant genes were also indicated, with the first dose in the triploid endosperm having a large effect while the second dose had little or none. Non-allelic interactions were significant in the second experiment where the use of more types of backcross made them more detectable. There were also small and significant residual effects of the maternal plant in the first experiment, attributed to the vigour of the F1 mother plant and to the cytoplasm of Sunco. Narrow-sense heritability was low, between 0.05and 0.18 depending on the generation. Transgressive segregation was not found, suggesting that all alleles tending to increase the B-granule content were found in the Sunco parent and none in ME71. There was also no detectable heterosis in this character. The results show that breeding and selection for a low B-granule content should be possible but a further reduction will require new and complementary genes. This revised version was published online in July 2006 with corrections to the Cover Date.     

水稻小孢子形成和发育过程中胼胝质的动态变化

利用活体荧光显微术,PEG切片荧光显微术,半薄切片光学显微术和透射电镜观察了粳稻台中65小孢子形成和发育过程中胼胝质的动态变化。结果发现,胼胝质最早于小孢子母细胞形成期出现于花粉囊中。进入小孢子母细胞减数分裂期,胼胝质首先在小孢子母细胞靠近药室中央的初生细胞壁上沉积,并于减数分裂Ⅰ终变期形成完整的胼胝质壁;随后胼胝质在小孢子母细胞中央开始沉积,并向四周扩展形成第1个赤道板,随后形成第2个赤道板;减数分裂后,四分体周围的胼胝质解体释放出小孢子。小孢子早期,绒毡层细胞中积累胼胝质类物质,小孢子核周围也开始沉积胼胝质,逐渐形成完整胼胝质壁;小胞子晚期,绒毡层细胞开始解体,药室内壁细胞开始加厚,其加厚的物质为胼胝质类物质。二胞花粉早期,小孢子进行不均等分裂,形成营养细胞和具有胼胝质壁的生殖细胞,随后营养细胞的细胞质中积累胼胝质,生殖细胞的胼胝质壁开始解体;二胞花粉晚期,药室内壁加厚完成,营养细胞的细胞质中继续积累胼胝质,花粉成熟期,营养细胞的细胞质中积累了大量胼胝质。对胼胝质在小孢子形成和发育过程中的功能进行了讨论。     

Fertility and pollen tube growth in polyploid melons (Cucumis melo L.)

The high sterility of tetraploid melon (Cucumis melo L.) plants is a serious inconvenient to obtain economically useful polyploid lines. In order to study the alterations on diploid pollen tube growth and their influence on sterility, in vitro and in vivo pollen tube growth from three commercial varieties and its tetraploids was observed. Polyploid pollen grains show a lower germination percentage in vitro and a slower germination rate than haploid pollen. Furthermore, diploid pollen grains producing two or three tubes and tube branchings were observed on diploid pollen; this seems to indicate a decrease in its functionality. In vivo and in vitro pollen behaviours are quite similar, but an interaction between the pollen and the pistillar tissues was detected in vivo. In the diploid × tetraploid cross, where fruits were not obtained, pollen tubes showed a slow growth rate at the base of the pistil. The possible effects of these alterations in sterility are discussed in terms of the factors that could affect fecundation. This revised version was published online in July 2006 with corrections to the Cover Date.     

水稻、大豆、玉米光合速率的日变化及其对光强响应的滞后效应

用LI-6400光合测定系统对水稻、大豆和玉米3种作物在不同生育时期叶片光合速率的日变化规律进行了研究。结果表明:在各个生育时期,C3作物(水稻、大豆)叶片的光合作用均存在午休现象。而午休现象的产生是气孔因素与非气孔因素共同作用的结果。其中“气孔因素”是高温加剧蒸腾作用,气孔对蒸腾作用的反馈抑制造成的。C3作物(水稻、大豆)叶片的光合速率对光强的响应在上午和下午存在明显差异,上午利用光能的能力明显大于下午。这主要表现在上午的表观初始量子效率比下午大。光合产物对光合作用的反馈抑制会造成这种量子效率的差异性。无论是气孔限制还是光合产物反馈抑制都可能是导致光合速率对光强响应产生“滞后效应”的主要原因。C4作物(玉米)的午休现象不明显,光合速率对光强的响应在上午和下午的差异也不明显,不存在明显的“滞后效应”,这可能与C4作物(玉米)自身的生理特性适应高温的能力有关。     

Changes in cuticular waxes of developing leaves in sesame (Sesamum indicum L.)

Sesame (Sesamum indicum L.) is one of the most important oil seed crops, which has been used as a traditional health food. The objective of this study was to investigate the changes of leaf cuticular waxes during plant growth from 5 to 75 days after seedling emergence, and the variation of leaf waxes with different leaf position; top, middle, and lower positions, using four Korean sesame cultivars, Ahnsan, Danbaeck, Hanseom, and Kyeongheuk. Alkanes in lower leaves and aldehydes in top leaves among leaf positions were the most abundant, with alkanes being with major portion in all leaf position of four sesame cultivars. Total leaf wax load decreased around three-fold between 5 and 30 days, and then remained constant up to day 75. The percentages of alkanes and aldehydes increased between 5 and 15 days and then changed little or increasingly, showing minor variation depending on sesame cultivars. The rate of increase of alkanes was slightly higher than that of aldehydes. Chain length of alkanes and aldehydes became longer from 5 to 30 days, and then remained almost constant till day 75. The major homologue in alkanes was the C29 at day 5 and the C33 constituent after day 30, while the major homologue in aldehydes was the C32 constituent continuously during leaf development. The results demonstrated that the chain length for alkane and aldehyde constituents changed increasingly by chain elongation and wax biosynthesis during leaf development of sesame.