Microstructural growth in otoliths of black rockfish,sebastes schlegeli, from prenatal larval to early juvenile stages

Microstructural growth in the sagittae ofSeastes schlegeli, a viviparous scorpaenid, is described from prenatal larval to early juvenile stages, and related to morphological changes. Embryos and prenatal larvae were extruded from a gravid female from 21 d prior to birth onwards, and released larvae reared and sampled up to 58 d after birth. Eggs hatched in the ovary 14 d prior to birth. At this time, otoliths consisted of a core surrounded by a prominent check, similar to the otolith structure seen in oviparous fishes. Fourteen growth increments had been deposited by birth. The parturition mark it-self comprised a prominent check and narrow growth increment Growth increments were deposited daily from hatching up to 58 d after birth, whereas accessory primordia first appeared in otoliths by ca. 32 d after birth, at a specimen total length of ca. 13 mm. This corresponded to the period during which the larvae metamorphosed into juveniles. Otoliths grew exponentially during the larval stage and linearly during the juvenile stage. when plotted against total length. Growth in total length from hatching to 58 d after birth could be represented by the Gompertz curve.     

Differences in size and growth rates of male and female migrating Japanese eels in Pearl River, China

The Sr/Ca ratios in otoliths of silver Japanese eels Anguilla japonica , in Pearl River, China, indicated that both sexes did not stay in brackish water and grew in fresh water from the glass eel stage until spawning migration. This did not support the hypothesis that females tended to distribute upstream and males might be restricted to estuaries. The back-calculated total length of males at glass eel stage was not significantly different from that of females, indicating that the hypothesis that small glass eels became males and larger ones became females may not be true. The mean (±S.D.) age and total length of males at migration were 6·4±1·6 years and 48·3±4·5 cm, which were significantly smaller than for females, 8·3±1·6 years and 61·4±4·1 cm. The age of migration was related inversely to growth rate for both sexes. Growth parameters of the von Bertalanffy growth equation were K =0·21 cm year°1, L _∞=55·7 cm and t _o=-0·55 year for males and K =0·14 cm year⁻¹, L _∞=77·5 cm and t _o=-0·60 year for females. The difference in asymptotic length ( L _∞) between males and females may be because females postpone migration to achieve larger size for maximizing reproductive success.     

Accuracy and repeatability of moose (<Emphasis Type="Italic">Alces alces</Emphasis>) age as estimated from dental cement layers

Optimal research and management of species with age structure often depends on estimates of age-specific population parameters, which in turn depends on reliable methods for age determination. By counting annuli in the cementum of incisor root tips from 51 known-age moose (Alces alces) between 1 and 12 years old, we examined the variation in accuracy and repeatability of age estimates provided by three research technicians with different experiences of aging moose. The most experienced technician estimated the moose age correctly in up to 90% of the cases, while the technician with no prior experience estimated age correctly in up to 73% of the cases. The medium-experienced technician achieved a lower accuracy (up to 53%), indicating that experience alone is not sufficient if the basic training or lack of routine checks against other colleagues or a known-age material are not undertaken. The percentage moose aged within ±1 year from correct age was significantly higher in all technicians (94–98%). After the generally high accuracy, we also found high repeatability (0.980–0.994) within technicians. We conclude that this method of age-determination provides reliable estimates that can be used by management and research to gain information about age-specific patterns in moose populations. However, to obtain estimates of high accuracy the technicians should be well trained, have gained the necessary experience, and most preferably, have access to a sample of teeth from known-age moose.     

植入了骨修复材料的小型猪腰椎椎体不脱钙病理组织切片制备方法

摘要 目的：建立植入了骨修复材料小型猪腰椎椎体骨组织标本的不脱钙病理组织切片制备方法。方法：将含骨修复材料的腰椎椎体骨组织标本进行分割暴露组织切面,梯度浓度乙醇脱水后经Technovit 7200 VLC光聚树脂浸润,经黄蓝光共同辐照进行光聚合包埋,借助硬组织病理切磨系统制备含骨修复材料不脱钙病理组织切片。结果：结果显示通过上述方法制备的病理组织切片,经苏木精-伊红（HE）染色及甲苯胺蓝染色后光学显微镜下观察能较好地显示骨的各种组织细胞结构,可清晰的观察到骨小梁的走向及连接情况。结论：研究建立了含骨修复材料骨组织标本病理组织切片制备方法,实现了含骨修复材料不脱钙骨组织病理切片的制备,经病理染色后实现了带植入物的组织学观察,为生物材料及医疗器械动物试验研究提供了新的病理检测手段及组织学评价途径。     

Effects of water depth and hydrodynamics on the growth and distribution of juvenile cyprinids in the littoral zone of a large pre-alpine lake

In enclosure experiments in the littoral zone of Lake Constance, Germany, juvenile cyprinids showed significantly reduced somatic growth in the shallow eulittoral zone (0·5 m depth) compared to the sublittoral zone (1·6 m depth). Growth was especially reduced in larger and more deep-bodied fish groups, providing evidence that this is due to increased hydrodynamic stress, induced by ship and wind waves, in the shallow habitats compared to the deep habitat. Other factors such as water temperature and food availability seemed to be of minor importance for the observed growth differences. Gillnet catches at the experimental site and an adjacent site showed that most juvenile cyprinids, including the species from the enclosure study, bream Abramis brama and dace Leuciscus leuciscus , nonetheless prefer shallow habitats compared to deeper sublittoral habitats. Juvenile cyprinids in Lake Constance may prefer these shallow habitats as refuges against larger piscivorous predators, mainly perch Perca fluviatilis , despite the cost in terms of reduced somatic growth indicating that juvenile cyprinids first of all optimize survival rate instead of somatic growth rate.     

Assessment of restocking as a strategy for rehabilitating a native population of brown trout Salmo trutta L. in a fast-flowing mountain stream in the northern French Alps

An attempt was made to extend the area of distribution of a native population of brown trout Salmo trutta belonging to a Mediterranean lineage (ML), which has maintained itself in the Dranse d'Abondance, a fast-flowing alpine stream (Haute-Savoie, France), despite several decades of intensive restocking with brown trout derived from the Atlantic lineage (AL). This was done by releasing an ML component into the predominantly AL population still present on the Ugine, the main tributary of the Dranse d'Abondance. This strategy of rehabilitation restocking was tested using fluoro-marked juveniles produced from a captive breeding stock derived from the wild Dranse d'Abondance ML stock. Samples of 0+ year fish were collected over the period 1995–2003 in order to assess the impact of the restocking. Percentages of fluoro-marked otoliths revealed significant contributions of ML restocking in the 0+ year autumnal standing population, with levels ranging from 34·3 to 61·4%. The change in the genetic characteristics of the 0+ year population produced by natural recruitment was monitored by analysing the unmarked subjects. Frequencies observed at two microsatellite loci revealed a considerable rise (from 0 to 60%) in the level of Mediterranean alleles in the natural 0+ year population since the introduction of restocking using ML individuals.     

Age of European silver eels during a period of declining abundance in Norway

The European eel (Anguilla anguilla) is critically endangered throughout its range. Knowledge about age distribution of future spawners (silver eels) is essential to monitor the status and contribute to the recovery of this species. Determination of age in anguillid eels is challenging, especially in eels from the northern part of the distribution area where growth is slow and age at maturation can be up to 30 years or more. Eels from the river Imsa in Norway have been monitored since 1975, and this reference time series has been used to assess the stock at the European level. Population dynamics in this catchment were analyzed during the late 1980s by estimating ages on whole cleared otoliths. However, techniques for revealing annual increments on otoliths have evolved over the years sometimes yielding significant differences in age estimates. In this study, the historical otolith data were reanalyzed using a grinding and polishing method rather than reading the whole otolith. The new age estimates were considerably higher than the previous ones, sometimes by up to 29 years. Since the 1980s, mean age of silver eels only slightly increased (from 19 to 21 years in the 2010s). This was mainly due to the disappearance of younger silver eels (<15 years) in the 2010s. The new age estimates agreed with the steep decline in recruitment which occurred in the late 1980s in the Imsa catchment. Mean growth (30 mm/year, min–max: 16–64 mm/year) has not changed since the 1980s, although density in the catchment has decreased. Revealing and reading age of slow‐growing eels remain a challenge but adding a measure of otolith reading uncertainty may improve age data collection and contribute to recovery measures for this species.     

Decreased D2-40 immunoreactivity in stored paraffin sections and methods for preserving it

D2-40, a monoclonal antibody against podoplanin, is a selective marker of lymphatic endothelium and is widely used for research on and diagnosis of pathology of lymphatic vessels. We examined the relation between the duration of tissue section storage and changes in immunostaining by D2-40 antibody; we evaluated also the effects of preservation methods on changes in immunostaining during storage. Staining by D2-40 was attenuated by long-term preservation of scalp skin and lymph node sections at room temperature. The attenuation of D2-40 staining in stored sections was improved by preservation at low temperature, i.e., 4° or ? 30° C. We investigated also the immunostaining of preserved tissue sections using NZ-1 and Lyve-1, which are antibodies against lymphatic endothelium markers. Staining by NZ-1 or Lyve-1 antibody was detected clearly in sections that had been stored for 16 weeks. Our study suggests that either long-term storage of D2-40 immunostained tissue sections should be avoided or the section should be preserved at low temperature.     

Three-dimensional architecture of the higher plant nucleolonema disclosed on serial ultrathin sections

Summary— The three-dimensional architecture of the nucleolonema of Vicia faba has been studied by applying a silver impregnation technique to serial ultrathin sections. This technique disclosed lateral and transverse segments of the nucleolonema which were heavily impregnated with silver. The lateral profiles of the nucleolonema segments were classified into three main categories; a segment made up of one to several rod-like filaments (type I); a ladder-like segment consisting of two parallel and of transverse filaments (type II); and a last type constructed from two parallel filaments (type III). Tracing of the lateral segments through serial sections has indicated that type I first appears, then either type II or III and finally type I reappears at the corresponding sites on sections. Types II and III remained constant in width, about 1.0 μm, along their longitudinal axes whereas the width of type I was significantly smaller than that of the two former. The lateral filaments of both types II and III showed heterogeneity in width on account of the presence of knobs intermittently distributed along them. The thickness of these knobs was about 0.35 μm. Combining the observations on serial ultrathin sections and the morphometrical data it is very probable that the elementary structure of the nucleolonema is a 0.35-μm thick filament that tightly coils up into a solenoid structure with a thickness of approximately 1.0 μm. This model can explain the appearance of open- and closed-argyrophilic rings in serial sections since transverse segments of the solenoid are expected to show the argyrophilic rings. The elementary filament of the nucleolonema solenoid was sometimes loosened. Judging from our cytochemical data at the electron microscope level, some argyrophilic proteins appear to reside in the axial space of the solenoid but both DNA and RNA were not detectable in this space.     

Patterns of increment width and strontium: calcium ratios in otoliths of juvenile rock blackfish, Girella elevata (M.)

Otoliths of juvenile Girella elevata (M.) were examined to obtain information about the environmental conditions experienced during early life. Patterns of increment deposition and elemental ratios in otoliths were compared in wild fish. A tetracycline experiment indicated that increments were deposited daily in juveniles. Although different patterns in the spacing of increments were found among juveniles collected at different locations and times, the widest increments were always found in the first 40 increments. Strontium: calcium (Sr: Ca) ratios increased with age in the otoliths of most wild G. elevata .
The patterns of increment width and Sr: Ca ratios were not related and, therefore, were probably not under the same relative control by environmental or physiological factors. Although the number of increments can be used to age juvenile G. elevata , the utility of increment widths and Sr: Ca ratios as environmental predictors in this species is questionable without experimental validation.