Cephalopods in the Diet of Albacore, Thunnus alalunga, from the Adriatic Sea

The stomachs of 56 albacore (Thunnus alalunga) caught in thesouthern Adriatic Seacontained 222 cephalopods, or 29% of prey.Most cephalopod remains were from smallspecimens. Juvenilesand adults of Heteroteuthis dispar (61.5% of cephalopods) weremorefrequently preyed upon in the `inshore' fishing area (bottomdepth: 100-700m); early juveniles of Todarodes sagittatus (21.6%)were more abundant `offshore' (750- 1,150 m); early juvenilesof Histioteuthis bonnellii (16.4%) wereexclusive of the latterarea. The estimated overall number of cephalopods dying of predationbyalbacore is 6.3 x 10⁶ specimens/fishing season (two months). (Received 6 May 1998; accepted 13 July 1998)     

Ultrastructural morphometry of blastogenesis

Summary As a companion to an earlier study, the morphometric attributes of stimulated (blast-derived) lymphocytes in mouse axillary lymph nodes have been established using stereological and autoradiographic methods. Blast transformation was induced in vivo with dinitrochlorobenzene (DNCB) and stimulated cells were labelled with tritiated thymidine. Random samples of cells were taken for light and electron microscopic morphometry.In comparison to the unstimulated lymphocyte, the stimulated cell increased in size and possessed a greater plasma membrane surface area. Increase in cell size was the result of increases in the volumes of all measured subcellular compartments both in the nucleus and the cytoplasm. Heterogeneity of the stimulated cell population precludes firm conclusions regarding the significance of all these ultrastructural changes, though alterations in cell surface are discussed in the context of known biochemical differences accompanying blastogenesis.M.M. Al-Hamdani was supported by a grant from the Ministry of Higher Education and Scientific Research, Republic of Iraq     

The potential use of scales for estimating age and growth of Mediterranean albacore (Thunnus alalunga)

The ability to accurately estimate the age of fishes is critical for conducting stock assessments and developing fishery management policies. Scales were collected from albacore, Thunnus alalunga, caught in the Mediterranean Sea during the years 1989–1995 to estimate their age and growth. Ages, which ranged from 1+ to 6+ years, were estimated from the interpretation of the concentric rings on the scales of 473 individuals that ranged in fork length from 55.5 to 89 cm. Males reached a greater size and age than females. The relatively close agreement in the mean lengths at ages estimated by scales and other techniques constituted a preliminary verification of the method. The von Bertalanffy growth model was fitted to mean lengths at estimated ages, resulting in the following growth parameters for the combined sexes: L_∞ = 86 cm, K = 0.4, t_o = ?0.8 years. Parameter estimates were in agreement with what is known about life history of the species in the Mediterranean. Moreover, the growth rates were consistent with length increment observations from five tag returns, which lend support to our working hypothesis that the scale‐rings are annual structures. When the Mediterranean albacore growth parameters were compared with those of Atlantic Ocean albacore using scale age estimates, there were significant differences between the two populations, and Mediterranean albacore remain significantly smaller than Atlantic Ocean albacore.     

Reproductive Dynamics and Potential Annual Fecundity of South Pacific Albacore Tuna (Thunnus alalunga)

The reproductive biology of albacore tuna, Thunnus alalunga, in the South Pacific Ocean was investigated with samples collected during broad-scale sampling between 2006 and 2011. Histology was done in a single laboratory according to standard protocols and the data analysed using generalized linear mixed-effects models. The sex ratio of albacore was female biased for fish smaller than approximately 60 cm FL and between 85 and 95 cm, and progressively more male biased above 95 cm FL. Spawning activity was synchronised across the region between 10°S and 25°S during the austral spring and summer where sea surface temperatures were ≥24 °C. The average gonad index varied among regions, with fish in easterly longitudes having heavier gonads for their size than fish in westerly longitudes. Albacore, while capable of spawning daily, on average spawn every 1.3 days during the peak spawning months of October to December. Spawning occurs around midnight and the early hours of the morning. Regional variation in spawning frequency and batch fecundity were not significant. The proportion of active females and the spawning fraction increased with length and age, and mature small and young fish were less active at either end of the spawning season than larger, older fish. Batch fecundity estimates ranged from 0.26 to 2.83 million oocytes with a mean relative batch fecundity of 64.4 oocytes per gram of body weight. Predicted batch fecundity and potential annual fecundity increased with both length and age. This extensive set of reproductive parameter estimates provides many of the first quantitative estimates for this population and will substantially improve the quality of biological inputs to the stock assessment for South Pacific albacore.     

Spatial and sex-specific variation in growth of albacore tuna (Thunnus alalunga) across the South Pacific Ocean

Spatial variation in growth is a common feature of demersal fish populations which often exist as discrete adult sub-populations linked by a pelagic larval stage. However, it remains unclear whether variation in growth occurs at similar spatial scales for populations of highly migratory pelagic species, such as tuna. We examined spatial variation in growth of albacore Thunnus alalunga across 90° of longitude in the South Pacific Ocean from the east coast of Australia to the Pitcairn Islands. Using length-at-age data from a validated ageing method we found evidence for significant variation in length-at-age and growth parameters (L(∞) and k) between sexes and across longitudes. Growth trajectories were similar between sexes up until four years of age, after which the length-at-age for males was, on average, greater than that for females. Males reached an average maximum size more than 8 cm larger than females. Length-at-age and growth parameters were consistently greater at more easterly longitudes than at westerly longitudes for both females and males. Our results provide strong evidence that finer spatial structure exists within the South Pacific albacore stock and raises the question of whether the scale of their "highly migratory" nature should be re-assessed. Future stock assessment models for South Pacific albacore should consider sex-specific growth curves and spatial variation in growth within the stock.     

Cumulative effect of the North Atlantic Oscillation on age‐class abundance of albacore (Thunnus alalunga)

The aim of this study was to look into possible relationships between climate and the inter‐annual variability of albacore (Thunnus alalunga) catch rates by age class observed during a recreational fishery tournament at the spawning grounds of S’Estanyol (Balearic Islands, Spain) in the years 2004–2009. The mean capture per unit effort (CPUE) was significantly higher when the mean of the North Atlantic Oscillation (NAO) experienced by the albacore in winter and spring of its life history (NAO_life) was negative than when the NAO_life was positive. A statistically significant negative relationship was obtained between NAO_life and the probability of a CPUE value for an age class and year being higher than the average CPUE for all the cohorts in that age class. The results suggest that local abundance of albacore in a spawning grounds could be related to environmental factors dependent on the NAO and that there may be a cohort‐age effect. It is hypothesized that factors dependent on the NAO, such as the abundance variation of small pelagic fishes as a response to the NAO variability, could have a cumulative effect over the good biological condition (fitness) of a long‐living fish predator such as the albacore.     

Ultrastructural alterations of the myocardium induced by doxorubicin

Morphologic changes in Doxorubicin (DXR)-induced cardiomyopathy are characterized by marked dilatation of the sarcoplasmic reticulum (SR). DXR was administered to New Zealand White rabbits for 5 or 8 weeks and the three-dimensional structure of the sarcotubular system in cardiac muscle cells from each rabbit was examined under a field-emission type scanning electron microscope (SEM) after removal of cytoplasmic matrices by the osmium-DMSO-osmium procedure. Five weeks after the initial injection of DXR, partial dilatation of the SR and damaged mitochondria with lysis of cristae were observed three-dimensionally. After 8 weeks, the three-dimensional structure of the SR showed extensive spherical ballooning which could be seen clearly in bold relief. Thus, we could directly visualize structural alterations of the sarcotubular system in DXR-induced cardiomyopathy using the SEM.     

Ultrastructural histogenesis of chicken myocardium]

The structure of the ventricular myocardium of the chick embryo was studied from the 4th day of incubation until one day after hatching. Special attention was paid to the differenciation of myofibrils, their branching at the level of stria Z and their relations with desmosomes.     

New Nuclear SNP Markers Unravel the Genetic Structure and Effective Population Size of Albacore Tuna (Thunnus alalunga)

In the present study we have investigated the population genetic structure of albacore (Thunnus alalunga, Bonnaterre 1788) and assessed the loss of genetic diversity, likely due to overfishing, of albacore population in the North Atlantic Ocean. For this purpose, 1,331 individuals from 26 worldwide locations were analyzed by genotyping 75 novel nuclear SNPs. Our results indicated the existence of four genetically homogeneous populations delimited within the Mediterranean Sea, the Atlantic Ocean, the Indian Ocean and the Pacific Ocean. Current definition of stocks allows the sustainable management of albacore since no stock includes more than one genetic entity. In addition, short- and long-term effective population sizes were estimated for the North Atlantic Ocean albacore population, and results showed no historical decline for this population. Therefore, the genetic diversity and, consequently, the adaptive potential of this population have not been significantly affected by overfishing.     

Haematological characteristics of albacore, Thunnus alalunga (Bonnaterre), and skipjack, Katsuwonus pelamis (Linnaeus)

Observations on haematological characteristics of albacore, Thunnus alalunga , and skipjack Katsuwonus pelamis , tunas, were made on blood samples collected from specimens immediately after they were caught and from an immobilized, restrained albacore sampled serially over a 24 h period. Results indicated eight types of blood cells in the peripheral circulation of both species. Lymphocytes were the most common leucocyte followed, in decreasing order, by neutrophils, eosinophils and monocytes in fish sampled immediately after being landed. Variations in differential and total white blood cell counts were observed in the immobilized, restrained albacore. High packed cell volumes and haemoglobin concentrations, typical for fast swimming fishes, were found in both species. Red blood cell counts were similar to those of other teleosts, and reticulocytes expressed as a percentage of mature erythrocytes were 6.1% and 5.2% for albacore and skipjack, respectively.     

Ultrastructural morphometry of bovine blastocysts produced in vivo or in vitro

The objective of this study was to compare the ultrastructure of bovine blastocysts produced in vivo or in vitro by using morphometric analysis. Blastocysts produced in vivo (multiple ovulations, MO) were obtained from superovulated Holstein cows. For blastocysts produced in vitro, cumulus-oocyte complexes aspirated from ovaries of Holstein cows were matured and fertilized in vitro. At 20 h postinsemination (hpi), zygotes were distributed into one of three culture media: 1) IVPS (in vitro produced with serum): TCM-199 + 10% estrous cow serum (ECS); 2) IVPSR (in vitro produced with serum restriction): TCM-199 + 1% BSA until 72 hpi, followed by TCM-199 + 10% ECS from 72 to 168 hpi; and 3) mSOF (modified synthetic oviductal fluid): mSOF + 0.6% BSA. At 168 hpi, six or seven grade 1 blastocysts from each of the four treatments (MO, IVPS, IVPSR, and mSOF) were fixed and prepared for transmission electron microscopy. Random micrographs of each blastocyst were used to determine the volume density of cellular components. Overall, as blastocysts progressed in development, the volume densities of cytoplasm and intercellular space decreased (P < 0.05) and the volume densities of mature mitochondria, nuclei, blastocoele, and apoptotic bodies increased (P < 0.05). Across treatments, the proportional volumes of nuclei and inclusion bodies were increased in inner cell mass cells compared with trophectoderm cells for mid- and expanded blastocysts. For blastocysts produced in vitro, the volume density of mitochondria was decreased (P < 0.05) as compared with that of blastocycts produced in vivo. The proportional volume of vacuoles was increased (P < 0.05) in blastocysts from the mSOF treatment as compared with blastocysts produced in vivo. For mid- and expanded blastocysts from all three in vitro treatments, the volume density of lipid increased (P < 0.05) and the volume density of nuclei decreased (P < 0.05) compared with those of blastocysts produced in vivo. In conclusion, blastocysts produced in vitro possessed deviations in volume densities of organelles associated with cellular metabolism as well as deviations associated with altered embryonic differentiation. However, the specific nature of these deviations varied with the type of culture conditions used for in vitro embryo production.     

Ultrastructural analysis of development of myocardium in calreticulin-deficient mice

Background  

Calreticulin is a Ca²⁺ binding chaperone of the endoplasmic reticulum which influences gene expression and cell adhesion. The levels of both vinculin and N-cadherin are induced by calreticulin expression, which play important roles in cell adhesiveness. Cardiac development is strictly dependent upon the ability of cells to adhere to their substratum and to communicate with their neighbours.     

Ultrastructural morphometry of bovine compact morulae produced in vivo or in vitro

The objective of this study was to compare the ultrastructure of bovine compact morulae produced in vivo or in vitro using morphometric analysis. Compact morulae produced in vivo were obtained from superovulated Holstein cows. Compact morulae produced in vitro were obtained from cumulus-oocyte complexes aspirated from ovaries of Holstein cows. The complexes were matured and fertilized in vitro. At 20 h postinsemination (hpi), zygotes were distributed into 1 of 3 culture media: 1) IVPS (in vitro produced with serum): TCM-199 + 10% estrous cow serum (ECS); 2) IVPSR (in vitro produced with serum restriction): TCM-199 + 1% BSA until 72 hpi followed by TCM-199 + 10% ECS from 72 to 144 hpi; 3) mSOF (modified synthetic oviductal fluid): SOF + 0.6% BSA. At 144 hpi, five grade 1 compact morulae from each of the four treatments were prepared for transmission electron microscopy. The volume density occupied by cellular components was determined by the point-count method using a sampling of seven to nine random micrographs from each compact morula. The volume density of lipid was greater (P < 0.05) in compact morulae from IVPS, IVPSR, and mSOF treatments compared with those produced in vivo. There was a reduced proportional volume of total mitochondria in compact morulae from the IVPS treatment compared with those produced in vivo (P < 0.05). For compact morulae from the IVPS culture treatment, the volume density of vacuoles was greater than that for compact morulae produced in vivo (P < 0.05). The cytoplasmic-to-nuclear ratio for compact morulae from the IVPS treatment was increased (P < 0.05) compared with the ratio for those produced in vivo. In conclusion, compact morulae produced in vitro differed ultrastructurally from those produced in vivo. Compact morulae produced in IVPS culture medium possessed the greatest deviations in cellular ultrastructure.     

Ultrastructural and physiological changes induced by atractylate in the canine myocardium.

The myocardial cellular response to the cardiac glycoside atractylate, a known inhibitor of mitochondrial adenine nucleotide translocation, was examined physiologically, morphologically, and morphometrically in eight dogs. An isolated in situ segment of left ventricular tissue was employed in these experiments to eliminate collateral flow and the potential for large sampling error. It was found that atractylate infusion rapidly induced physiological and morphological changes suggestive of a loss of membrane regulation of ion flux in the arteriole, capillary endothelium, and myocardial cell. Also mitochondrial changes suggestive of adenine nucleotide translocase inhibition were observed. As these responses are similar to those induced by acute myocardial ischaemia, it is suggested that ischaemia and atractylate induce cell injury by similar mechanisms.     

Ultrastructural morphometry of the human sperm flagellum with a stereological analysis of the lengths of the dense fibres

The dimensions of the various regions of the flagellum and the length of each of the dense fibres has been determined by transmission electron microscopy of a large number of spermatozoa from ten men. The overall mean length of the flagellum was 60.5 micron, and its diameter diminished from 0.88 micron in the midpiece to 0.17 micron at the terminal filament. The midpiece and terminal filament as measured in longitudinal sections had variable lengths among spermatozoa (3.4 +/- 0.5 (S.D.) micron and 3.1 +/- 1.0 micron respectively). Stereological analysis was used to estimate the length of the principal piece (53 micron) and the dense fibres. These latter fibres were of unequal length and extended along 60% of the length of the principal piece. They fell into 3 groups with respect to their lengths: (i) fibres 3 and 8 were short (6 micron); (ii) fibres 4, 2 and 7 were of medium length (17, 18 and 21 micron respectively); and (iii) the longest fibres were 5, 6, 9 (31, 32 and 31 micron respectively) and fibre 1 which was a little longer (35 micron). Although there was variation in the length of the various fibres among spermatozoa, the order of their termination was relatively constant. The relationship between these quantitative data regarding the structural characteristics of the dense fibres and the shape of the flagellar wave is discussed.     

Maturity Ogives for South Pacific Albacore Tuna (Thunnus alalunga) That Account for Spatial and Seasonal Variation in the Distributions of Mature and Immature Fish

Length and age at maturity are important life history parameters for estimating spawning stock biomass and reproductive potential of fish stocks. Bias in estimates of size and age at maturity can arise when disparate distributions of mature and immature fish within a population are not accounted for in the analysis. Here we investigate the spatial and temporal variability in observed size and age at maturity of female albacore tuna, Thunnus alalunga, using samples collected across the South Pacific. Maturity status was identified using consistent histological criteria that were precise enough to allow for mature but regenerating females to be distinguished from immature females during the non-spawning season, permitting year-round sampling for maturity estimation in albacore. Using generalised linear mixed models, we found that the proportion of mature females at length varied significantly with latitude and time of year. Specifically, females at northern latitudes (∼10–20°S, where spawning occurs) were mature at significantly smaller lengths and ages than females at southern latitudes (∼20–40°S), particularly during the spawning season (October–March). This variation was due to different geographic distributions of mature and immature fish during the year. We present a method for estimating an unbiased maturity ogive that takes into account the latitudinal variation in proportion mature at length during a given season (spawning or non-spawning). Applying this method to albacore samples from the western region of the South Pacific gave a predicted length at 50% mature of ∼87 cm fork length (4.5 years).     

Ultrastructural morphometric studies of the myocardium of cardiomyopathic hamsters of the BI0 8262 strain

Tissue of myocardium from (8262) hamsters, 2, 6 and 27 weeks of age, were analyzed with quantitative microscopic techniques. Besides alterations of some other structures, we found the most evident changes in the mitochondrial abnormalities exist at all ages. They may be related to defective energetic mechanism.     

Ultrastructural morphometry of matrical changes induced by exercise and food restriction in the rat calcaneal tendon.

The ultrastructural morphometry of collagen fibril populations in 24 calcaneal tendons obtained from 12 Fischer 344 rats were studied to elucidate matrical changes induced by food restriction and/or endurance exercise. Rats were randomly assigned to four equal groups: ad libitum control (AC), ad libitum exercise (AE), restricted diet control (RC) and restricted diet exercise (RE) groups. Beginning from 6 weeks of age, animals in the two food restriction groups were fed 60% of the mean food consumption of ad libitum fed rats. Then, starting from 6-7 months of age, the rats in the two exercise groups performed 40-50 min of treadmill running at 1.2-1.6 miles h-1 every day for a total of 10 weeks. Endurance training did not significantly alter body weight, but food restriction with or without exercise resulted in a significant loss of body weight. In ad libitum fed controls, food restriction alone did not significantly alter the mean collagen fibril CSA, but predisposed a preponderance of small-sized collagen fibrils. Endurance training per se induced a significant (32%) increase in mean fibril CSA (P less than 0.05), but this adaptive response to exercise was prevented by food restriction, as indicated by a 33% decline in fibril CSA (P less than 0.05). These findings demonstrate that dietary restriction modifies the adaptation of tendon collagen morphometry in response to endurance training, and that weight loss is better achieved with food restriction than endurance exercise.