Large Oil Globule Research Articles

The Fate of the Yolk Syncytial Layer during Postembryonic Development of Stenodus leucichthys nelma

The yolk syncytial layer (YSL) is a multifunctional transient structure of teleost embryos and larvae. The YSL performs nutritional, morphogenetic and immune functions. However, the data on the YSL structure in different teleost species is fragmented. We aimed to characterize YSL of the postembryonic inconnu (Stenodus leucichthys nelma) along with the depletion of maternal reserves by analyzing serial histological sections. At hatching, the yolk complex was located anterior to the liver and contained a large oil globule (OG) in the front region, 1–2 additional OG, and the yolk itself. The YSL region around the OG was striated, the region surrounding the yolk was regionalized in an apico-basal direction. The yolk syncytial nuclei (YSN) were large and complex-shaped. The yolk was exhausted by approximately the 17th day post hatching (dph). One–two large OG remained in the yolk complex until the programmed death of the YSL at 31 dph. The organization of the larval yolk complex of the inconnu was typical for Coregonidae. The abundance of comet-shaped YSN was its peculiarity.

Age at stocking is a decisive factor on growth and survival of the Indian shad, Tenualosa ilisha during nursery rearing in fertilized earthen ponds

Hilsa, Tenulosa ilisha is an important commercial fish of the Indo-Pacific region. The larvae of hilsa can survive for quite long without exogenous feed due to the presence of large yolk sac and oil globule. Therefore it is important to understand the suitable age of hilsa larvae to be used for nursery rearing. In this study, larvae were produced through artificial breeding of mature migratory fish collected from wild. Three different age groups of hilsa larvae, such as three days post hatched (3 DPH, just before yolk sac exhaustion, swim mostly vertically, TL: 4.21 ± 0.02 mm), 5 DPH (with oil globule, swim vertical and horizontal, TL: 5.26 ± 0.12 mm) and 12 DPH (just before oil globule exhaustion, swims very fast, TL: 6.00 ± 0.11 mm) were randomly distributed in nine well prepared rectangular earthen ponds (100 m2) in triplicate (n = 3) at the stocking density of 500 number m−3. The nursery rearing was carried out for 90 days. Results showed no significant difference in water quality parameters in different experimental ponds (p > 0.05). Dissolved oxygen, temperature, pH, total ammonia nitrogen, chlorophyll-a, gross primary productivity, total plankton count ranged from 7.24–7.46 mg L−1, 29.00–30.38 °C, 8.16–8.43, 110–124 μg L−1, 17.33–22.66 μg L−1, 193–203 mg C m−3 h−1, 2.2 × 104–2.4 × 104 numbers mL−1, respectively. After 60 days of the nursery, to imitate the larval migration towards low saline water, salinity was increased at the rate of 0.5 g L−1 on alternate days to 7.4 g L−1. There was no significant difference (P > 0.05) in daily weight gain and final total length and weight of fish in different experimental groups, however specific growth rate varied significantly (p < 0.05). At the end, hilsa larvae attained a total length of 43.3 ± 0.074 mm, 41.4 ± 0.04 mm, 39.2 ± 0.051 mm, in 3, 5 and 12 DPH groups, respectively. Percentage survival was significantly (p < 0.05) highest (3.40 ± 0.81%) in 5 DPH treatment. Water and gut plankton analysis showed that hilsa larvae are not a selective feeder, but feeds on available food items in the ecosystem through filtration. Length-weight relationship indicated the negative allometric growth (b < 3) pattern in all three groups. Overall, this experiment suggested that 5 DPH is an ideal age for shifting hilsa larvae from larval rearing tank to nursery pond.

Early Ontogeny of the Climbing Perch Anabas testudineus (Anabantidae) in Relation to the Buoyancy Dynamics

This article describes early development of the climbing perch Anabas testudineus in relation to its buoyancy dynamics. Main patterns of the ontogeny during the first 140 h of development are described. The climbing perch is characterized by positive buoyancy of eggs and early larvae not usually found in other freshwater fish. This allows the fish development close to the surface of the water and is enabled by a large oil globule in the yolk. The data on the spatial orientation of the larva body, their vertical distribution in the water column, the beginning of exogenous feeding and locomotion, and the fright reaction of the larvae at different ages are presented. The most significant changes in the behavior of the climbing perch larvae are associated with changing the shape of the yolk sac, beginning to function as a provisional hydrostatic organ from about the 80s hour of development.

Oil globule size in fish eggs: A matter of biome and reproductive strategy

AbstractHere, on the basis of published information upon over 800 species from 39 orders and 202 families, we analyse how the size of oil globules in fish eggs varies between reproductive guilds and environments with contrasting salinities. About 80% of marine fishes produce eggs with oil globules, the volume of which (VO) never exceeds 9% of the egg reserves and averages 2%. These proportions vary very little between marine fish species producing pelagic or demersal eggs. Fewer freshwater fishes (about 40%) produce eggs with oil globules, but their globules are much larger (mean VO of 10%) and their volumes vary considerably between reproductive guilds: VO is on average 3–10 times lower in freshwater species with demersal eggs than among freshwater pelagophils and aphrophils (i.e., bubble nesters), where it averages about 40% (range of 23%–69%) of the egg reserves. These results support the idea that oil globules serve to hydrostatic lift in fresh waters, but not or very little in marine waters, where egg buoyancy can be achieved at a lower energy cost through egg hydration. Advantages and constraints of oil globules in fish eggs are discussed in the light of species producing eggs with very large oil globules (VO &gt; 20%): access to oxygen‐rich water layers that are indispensable for egg development vs. smaller size of larvae at first feeding, since the saturated lipids contained in oil globules essentially serve very little to tissue construction.

Oocyte Development and Staging in the Florida Bass,Micropterus floridanus(LeSueur, 1822), with Comments on the Evolution of Pelagic and Demersal Eggs in Bony Fishes

Oocyte development and staging is described from histological preparation of the ovaries of field collected specimens of the Florida Bass, Micropterus floridanus. Oocyte development in Florida Bass progresses through six stages beginning with oogonial proliferation and ending with ovulation, the release of eggs. The stages are based on mitosis and meiosis, the core processes of Adaptable Oocyte Staging. After ovulation, the postovulatory follicle complex produces a mucus-like fluid with unknown function; we speculate that it protects the eggs immediately upon ovulation and upon their release into freshwater during spawning. Atresia is rare in the ovaries of reproductive Florida Bass. The release of cortical alveoli after fertilization follows a unique, extended time-release sequence. Oocyte development in the freshwater perciform Florida Bass follows precisely a pattern that has been documented for marine perciform fishes that produce positively buoyant, pelagic, non-adhesive eggs. The eggs of Florida Bass are morphologically like these pelagic eggs in that they have a single large oil globule and no attachment filaments. Yet Florida Bass eggs have small, clear yolk globules and an adhesive egg envelope and are functionally demersal. Thus, classification of an egg as pelagic or demersal should consider its morphology as well as its function, especially if egg type is to be used to interpret phylogenetic relationships or evolutionary patterns. The clearing of yolk due to the uptake of water during the development of actinopterygian eggs, as they progress from a demersal to a potentially pelagic phase, may be a general mechanism of oocyte maturation in teleost fishes.

Structure of the yolk syncytial layer in the larvae of whitefishes: A histological study

The yolk syncytial layer (YSL) is a symplastic provisory system that forms at the early stages of embryogenesis of teleosts. The YSL serves morphogenetic, trophic, and immune functions. Despite its important role in development, data on the structure of YSL is scarce. In the present study, comparative histological research on the features of YSL structure in the development of larvae of four economically important species of Coregonidae (Salmoniformes)—Coregonus peled, Coregonus muksun, Coregonus nasus, and Stenodus leucichthys nelma—is presented. The YSL of the larvae of Coregonidae has a complex, differentiated structure. Functional regionalization of YSL cytoplasm, possibly determined by the specific features of nutrient assimilation, is typical for all aforementioned species. Cytoplasm that encircles a large oil globule appears striated. A division into an inner area, filled with yolk inclusions, and an outer, smoother homogeneous area, can be noted in the cytoplasm surrounding the yolk mass. The oil globule is retained after complete utilization of the yolk mass. The inequality of thickness of YSL along anteroposterior and dorsoventral axes also indicates the functional regionalization. The dorsomedial area of YSL, located under the intestine, is the least thick. Dorsolateral areas are strongly incrassated and envelop the intestine from two sides. Gigantic nuclei of exceptionally complex form are typical for YSL. Specific features apply to the form of YSL and its nuclei. Based on the obtained results, a fundamental similarity in organization of the YSL of larvae of the studied whitefishes can be concluded; however, its specific variations distinguishable on a histological level can be discussed.

Embryonic and early larval development of Cottus czerskii Berg, 1913 (Scorpaeniformes: Cottidae)

The embryonic and early larval development of the Cherskii’s sculpin Cottus czerskii Berg, 1913 was studied. The duration of the embryonic period was 21 days at a water temperature of 9–10°C. Pelagic larvae of approximately 8.0 mm total length leave the egg envelopes, with a large rounded yolk sac with one large oil globule, 10–12 trunk and 30–31 precaudal myomeres and several large melanophores on the yolk sac, 2 melanophores in the peritoneal region, and 30 melanophores in a postanal ventral row. At 11 days after hatching at a length of 9.0 mm, the yolk sac is completely resorbed and the number of myomeres remains the same; seven rays become visible in the caudal fin. The fully formed larva of C. czerskii has an elongated body, a small head, a rounded snout, and an oblong tail part. The melanophores are located in the peritoneal area above the gut, in the abdominal area, and in the postanal ventral row. Armament in the form of spines on the top of the head is absent, pointing to the affiliation of the species that we studied to the Cottus–Leptocottus phenetic group.

A contribution to the familyLecideaceaes. lat. (Lecanoromycetidaeinc. sed., lichenized Ascomycota) in the southern subpolar region; including eight new species and some revised generic circumscriptions

AbstractEight new species ofLecideaceaeare described from the southern subpolar region:Bryobilimbia coppinsianaFryday, a saxicolous species with one septate ascospores (Campbell Island, New Zealand);Immersaria fuliginosaFryday, with a thallus composed of thalloconidia (Falkland Islands);Lecidea aurantiaFryday, with an orange thallus (Auckland Islands, New Zealand);L. campbellensisFryday, with an endolithic thallus and apothecia resembling those of a species ofPorpidia(Campbell Island);Poeltiaria ochyraeHertel, which is similar toP. subinconguabut with a thick areolate thallus (South Orkney and South Shetland Islands);P. tasmanicaFryday, which is similar toP. urbanskyanabut with smaller ascopores (Tasmania);Poeltidea inspersaFryday with an enolithic thallus and a hymenium with large oil globules (Falkland Islands); andPorpidia vulcanoidesHertel &amp; Fryday with immersed apothecia with a thick margin and large ascospores (SW Chile).Lecidea kalbiiHertel is resurrected from the synonymy ofL. manniiTuck. and treated as a distinct species. The circumscription of genera within theLecideaceaeis also discussed:Poeltiariais shown to be heterogeneous, and the generaLabyrinthaandNotolecideaare reduced to synonymy withPoeltideaandPoeltiariarespectively, and the new combinationsPoeltidia implexa(Malcolmet al.) Hertel &amp; Fryday andPoeltiaria subcontinua(Hertel) Hertel &amp; Fryday made. A key to the genera ofLecideaceaes. lat. is provided.

Oogenesis of microlecithal oocytes in the viviparous teleost Heterandria formosa

Viviparous teleosts exhibit two patterns of embryonic nutrition: lecithotrophy (when nutrients are derived from yolk that is deposited in the oocyte during oogenesis) and matrotrophy (when nutrients are derived from the maternal blood stream during gestation). Nutrients contained in oocytes of matrotrophic species are not sufficient to support embryonic development until term. The smallest oocytes formed among the viviparous poeciliid fish occur in the least killifish, Heterandria formosa, these having diameters of only 400 μm. Accordingly, H. formosa presents the highest level of matrotrophy among poeciliids. This study provides histological details occurring during development of its microlecithal oocytes. Five stages occur during oogenesis: oogonial proliferation, chromatin nucleolus, primary growth (previtellogenesis), secondary growth (vitellogenesis), and oocyte maturation. H. formosa, as in all viviparous poeciliids, has intrafollicular fertilization and gestation. Therefore, there is no ovulation stage. The full-grown oocyte of H. formosa contains a large oil globule, which occupies most of the cell volume. The oocyte periphery contains the germinal vesicle, and ooplasm that includes cortical alveoli, small oil droplets and only a few yolk globules. The follicular cell layer is initially composed of a single layer of squamous cells during early previtellogenesis, but these become columnar during early vitellogenesis. They are pseudostratified during late vitellogenesis and reduce their height becoming almost squamous in full-grown oocytes. The microlecithal oocytes of H. formosa represent an extreme in fish oogenesis typified by scarce yolk deposition, a characteristic directly related to matrotrophy.

Emulsification and inverted hypopyon formation of oxane HD in the anterior chamber

Oxane HD(R) is a "heavier-than-water" silicone oil which has a specific gravity of 1.02 g/cm(3). When dispersed into droplets, one expects them to sink. We report a case of emulsification of Oxane HD in an eye that unexpectedly manifested as an "inverted hypopyon". The clinical findings of a 45-year-old man who underwent pars plana vitrectomy and Oxane HD endotamponade for a phakic inferior rhegmatogenous retinal detachment are described. A large silicone oil globule was noted to be floating in the anterior chamber on postoperative day 1. Emulsification of the globule and inverted hypopyon formation were subsequently observed at 2 months postoperatively. Emulsification and inverted hypopyon formation in the anterior chamber may occur with Oxane HD. One explanation might be that the Oxane HD has separated out into its constituent components of silicone and RMN3, which raises questions as to the basis for its claim to be a heavier-than-water tamponade.

Trade-offs between size and energy reserves reflect alternative strategies for optimizing larval survival potential in rockfish

Reproductive strategies balancing offspring size and offspring number have been well documented in empirical tests of life-history theory. Here we found an additional trade-off between offspring size and offspring condition. Among 5 species of live-bearing rockfishes (Sebastes spp.) from central Californian populations, we observed a negative relationship between larval length at parturition and the size of their oil globule (a triacylglycerol-rich energy reserve). When compared with a variety of performance variables (resistance to starvation, growth, startle-escape performance and routine activity levels), it appears that this trade-off leads to a conflict when trying to optimize survival potential, with differing benefits to each trait. A large oil globule greatly increases resistance to starvation, whereas larger body size is associated with numerous performance benefits likely to synergistically decrease predation-based mortality and increase success at capturing prey (increased startle speeds and distances, as well as more rapid onset of growth and larger size at age). The tradeoff between energy reserves and body size is further reflected in the seasonal patterns of parturition of the 5 species, with larvae having large oil globules and small body size being released in winter, when productivity in the California Current is low but transport is generally onshore, and those with small oil globule reserves and large body size released in late spring, when productivity is high but transport is generally offshore. These 2 apparent reproductive strategies also reflect subgeneric phylogenetic relationships, suggesting a potential lineage-specific basis for the contrast in larval traits. The results highlight the importance of measuring both physical and performance traits of larvae, as well as considering multiple attributes of both, when evaluating progeny quality.

Coral reef fish breeding: the secrets of each species

Abstract In recent years, the interest in the trade of tropical fish has increased significantly, with direct negative repercussions on coral reefs and marine ecosystems. The reproduction and rearing of some of the species most commonly used in the aquarium trade actually represent an economical and ecological tool for broadening development. The present study illustrates the first case ever of a small Indo-Pacific Pomacentridae, Chrysiptera parasema , successfully reared in captivity. Eggs were obtained from spawners reared in 80-l tanks under controlled conditions. Spawning began after 3 months: the couples were formed, and eggs were laid after a brief courtship. The male normally guarded the nest and chased away the female if she entered it. The eggs, about 300 in number, are demersal and elongate ovoidal in shape, measuring approximately 1.2–1.5 mm and coming with a large oil globule. Hatching took place at 28 °C during the first 2 h of darkness, over a total time period of 96 h. A proper diet of enriched PUFA as a first food, combined with a photoperiod of 24L/0D, proved essential for survival of the C. parasema larvae. These results are very promising in terms of both future captive production of ornamental fish and efforts to minimize environmental impact.

Apolipoprotein E gene expression correlates with endogenous lipid nutrition and yolk syncytial layer lipoprotein synthesis during fish development.

During embryogenesis of teleost fish, the formation of a yolk syncytial layer (YSL) enables the resorption of the yolk reserves and development up to the larval stage. We have examined the changes of the yolk cell structure in relation to yolk and oil-globule lipid utilization during development of the turbot (Scophthalmus maximus). After encapsulation by the YSL, resorption of the single, large oil globule occurred predominantly after yolk resorption and was slower in fasting larvae. The YSL was in contact with an enlarged perisyncytial space, but no vascular network or red blood cells were present within the walls of the yolk sac. Intrasyncytial channels infiltrated by pigmented lining cells were observed in the YSL surrounding the oil globule. Apolipoprotein E (apoE) has a prominent role in lipid metabolism because of its ability to interact with lipoprotein receptors. We performed molecular cloning of the putative low-density lipoprotein-receptor binding domain of turbot apoE. In situ hybridization analysis revealed a very high level of apoE transcripts in the YSL, while no expression could be detected in the intestine. YSL apoE expression was correlated with the synthesis of very low density lipoprotein (VLDL) particles. An extraordinarily high number of VLDL particles were poured into the perisyncytial space, and intrasyncytial channels enabled the transfer of yolk- and oil globule-derived lipids to the developing embryo or larva. The pattern of apoE mRNA distribution in relation to YSL lipoprotein synthesis indicates that apoE expression is a suitable molecular marker for monitoring endogenous lipid nutrition during the endoexotrophic period of teleost fish development.

Morphology of Ruffe (Gymnocephalus cernuus) Protolarvae from the St. Louis River, Lake Superior

ABSTRACT We describe hatching and the morphological and meristic characteristics of 2.5–5.6 mm long ruffe protolarvae (Gymnocephalus cernuus). Eggs and sperm from St. Louis River ruffe were mixed, producing fertilized eggs that were 0.9–1.2 mm in diameter. Newly hatched protolarvae were 2.5–3.2 mm long. They had 14–15 preanal and 23–24 postanal myomeres, a continuous finfold of even width, unpigmented eyes, and a large anterior oil globule in the yolk sac, and the head deflected over the yolk sac. Pectoral fin buds appeared on the dorsal side of the yolk sac 5 hours after hatching. Two-day-old protolarvae had fully pigmented eyes, and the head was free from the yolk sac. Three-day-old protolarvae were 3.9–4.3 mm long and possessed opercula, gills, pectoral fins, and a functional jaw. Feeding and swimming began about one week after hatching when the yolk sac was almost completely absorbed. Protolarvae grew rapidly at 20–22°C and were 4.9–5.6 mm long after 13 days. Newly hatched ruffe protolarvae are distinguished from other Lake Superior percids by having the fewest preanal myomeres (14–15), the head deflected over the yolk sac, continuous finfold of even width, and a total length of less than 4.0 mm.

Biology and description of a bythitid fish from deep-sea thermal vents in the tropical eastern Pacific

A new fish species of the world-wide genus Bythites (Bythitidae, Ophidiiformes) is based on a gravid female captured in a thermal vent in the Galapagos Rift Zone. No apparent morphological features of adults or larvae account for life in the vent environment. Gill arch structure does not indicate filter feeding. The few fish species living in vents are not representative of ancient groups and are probably recent arrivals. The species is intermediate between the nominal genera Bythites and Abythites; hence, the latter is considered a junior synonym. The new species differs from its four congeners in its high dorsal, anal, and pectoral fin ray counts and its broad interorbital space. Free sperm and spermozeugmata are present throughout the ovarian tissue. Intra-ovarian larvae have a well-developed yolk sac, large oil globule, and pigmented eyes. Brood size is about 10,000.

Ecological studies on fishes of Zostera bed at the mouth of Ago Bay, Mie Prefecture - III. Development of eggs, larvae and juveniles of the tidepool gunnel Pholis nebulosa, reared in the laboratory.

Embryonic, larval and juvenile development of the tidepool gunnel Pholis nebulosa were described based on a series of laboratory-reared specimens. The eggs were demersal, almost spherical in shape, measuring 1.70-2.18mm in diameter, and with a large oil globule and several small ones. Neighboring eggs adhered to each other to form a spherical egg mass. Hatching occurred between 25 and 35 days after spawning at a water temperature of 11.5-13.5°C. Newly hatched larvae measured 8.3-11.6mm TL, and possessed 85-88 myomeres. Absorption of the yolk was completed at about 11.5mm TL. Flexion of the notochord started and finished at about 15mm and about 25mm TL, respectively. Aggregate numbers of all fin rays were com-pleted at over 27mm TL, when the larvae reached the juvenile stage. Squamation started in juveniles over 30mm TL.

The removal of silicone oil from the anterior chamber in phakic eyes.

The appearance of large silicone oil globules in the anterior chamber of phakic eyes leads to serious intraoperative and postoperative problems. Using hyaluronate sodium, the silicone can be safely removed from the anterior chamber, the crystalline lens may be saved, and the posterior segment procedure can be completed.

The causes of buoyancy in eggs of marine teleosts

Pelagic eggs and demersal eggs of teleosts both have osmotic concentrations similar to that of the maternal body fluids, less than half that of sea water. Pelagic eggs are buoyant because they contain such large quantities of this dilute aqueous fluid. While the demersal eggs of teleosts usually have a water content of 60–70%, the buoyant pelagic eggs of marine teleosts such as whiting, Norway pout, saithe, cod, haddock, turbot, dab, plaice, witch, long rough dab, halibut and sole typically have a very high water content (ca. 92 %) and a lipid content of 10–17% of egg dry weight. About 90% of the buoyancy of such eggs in sea water is caused by their high aqueous content, only about 10% being caused by lipid. The buoyant eggs of grenadier and ling have large oil globules and higher lipid contents, 27 and 35 % of dry weight respectively. Nevertheless, most of their buoyancy is provided by their high aqueous contents (89 and 81 % water). The high water content of pelagic eggs is brought about by a massive influx of water into the oocytes during meiotic maturation (ripening) after vitellogenesis but before ovulation. In cod and plaice, ripening is accompanied by a four- to five-fold increase in both water content and free amino-acids, and by a large influx of both potassium and sodium. In cod, free amino-acids contribute much more than these inorganic ions to the water influx and to the total osmotic concentration of the mature egg, but in plaice the relative contribution of inorganic ions approaches that of the free amino-acids.

Feinstrukturelle Untersuchungen zur Entwicklung der Ölzellen bei dem LebermoosRiella

Liverworts are characterized by the possession of typical cell elements, the oil bodies. In the submerse, thalloid liverwortRiella helicophylla (Sphaerocarpales) oil bodies are existing in idioblastic cells only, called oil body cells. Each oil body cell contains only one oil body. The oil body originates from small vacuoles. Their membranes are extremely high in contrast and asymmetric. The lipophilic substances are probably produced inside the oil bodies. At the end of the development of an oil body cell lipophilic and hydrophilic material will be separated from each other inside the oil body. The result is an oil body, consisting of one large spherical oil globule surrounded by a thin layer of hydrophilic matrix.

Early ontogeny of walleye,Stizostedion vitreum, with steps of saltatory development

Frequent in vivo observations of arbitrary stages revealed a saltatory pattern of development in the early ontogeny of fluvial spawning walleye. The requirement for an environment rich in dissolved oxygen was indicated by i) spawning site characteristics, ii) the lack of carotenoid pigments, iii) swim-up at hatching, iv) a planktonic (pelagic) existence by means of immobile surface suspension and subsequent surface swimming, and v) a poorly developed temporary embryonic respiratory system, including a subintestinal-vitelline vein, hepatic-vitelline vein and duct of Cuvier. Between the start of hatching and development of the ability to remain planktonic, the temporary embryonic respiratory system was enhanced by an increase in the proportion of the total blood volume passing through the subintestinal-vitelline vein — the largest respiratory surface. Immobile surface suspension was possible due to both the buoyancy of the large oil globule and the forces of surface tension. Also, immobile surface suspension would provide low energy transport from the fluvial spawning grounds to the lacustrine environment where zooplanktonic prey would be relatively more abundant. An intimate relationship between oil globule size (shape) and a dynamic behavioral transition (including the consumption of larger particles, cannibalism, and swimbladder inflation) suggested that energy expenditures occurring during fluvial transport were necessary for appropriate developmental synchrony.