Reproductive guilds (maturation,spawning frequency and fecundity) in the black pomfret,Parastromateus niger (Carangidae) in the Kuwaiti waters of the Arabian Gulf

Oogenesis, oocyte maturation pattern, spawning rhythm, spawning frequency, batch fecundity and oocyte diameter–frequency distribution of the black pomfret, Parastromateus niger (Bloch, 1795) in Kuwaiti waters were investigated from October 2003 to September 2005, using histological and morphological methods. The process of development is divided into four major phases: (i) primary growth phase; (ii) secondary growth phase; (iii) maturation phase; and (iv) spawning phase, followed by the regressed phase. Development of the yolky oocyte is an asynchronous process resulting, by the time of oocyte maturation, in a clear differentiation between a ready batch of oocytes (ready for spawning) and a reserve pool. Consequently, P. niger is capable of spawning multiple times throughout the reproductive season. Spawning frequency estimates, based on final oocyte maturation (FOM) method indicated that the species spawns once every 2.8 days during an 8‐month spawning season lasting from February to September, with a potential annual number of 22.4 spawns. Batch fecundity (BF) (2132–2001 648, mean 406 010 eggs), was significantly positively related to both standard length (SL) (P < 0.05) and ovary‐free body weight (OFBW) (P < 0.05), both parameters being good predictors of BF (r² = 30.8% for SL, from 22 cm onwards, and r² = 29.6% for OFBW, from 129.5 g onwards). No significant differences in monthly BF were found throughout the spawning season. Relative batch fecundity was 336 eggs/g OFBW; thus, estimate for potential annual relative batch fecundity was 7526 eggs g^?1 OFBW. The oocyte diameter–frequency distribution analysis revealed a multimodal distribution (at 100–200, 300–400 and 500–700 μm), confirming the evidence of multiple spawning.     

A relaxin‐like gonad‐stimulating peptide identified from the starfish Astropecten scoparius

A relaxin‐like gonad‐stimulating peptide (RGP) in starfish was the first identified invertebrate gonadotropin responsible for final gamete maturation. An RGP ortholog was newly identified from Astropecten scoparius of the order Paxillosida. The A. scoparius RGP (AscRGP) precursor is encoded by a 354 base pair open reading frame and is a 118 amino acid (aa) protein consisting of a signal peptide (26 aa), B‐chain (21 aa), C‐peptide (47 aa), and A‐chain (24 aa). There are three putative processing sites (Lys‐Arg) between the B‐chain and C‐peptide, between the C‐peptide and A‐chain, and within the C‐peptide. This structural organization revealed that the mature AscRGP is composed of A‐ and B‐chains with two interchain disulfide bonds and one intrachain disulfide bond. The C‐terminal residues of the B‐chain are Gln‐Gly‐Arg, which is a potential substrate for formation of an amidated C‐terminal Gln residue. Non‐amidated (AscRGP‐GR) and amidated (AscRGP‐NH₂) peptides were chemically synthesized and their effect on gamete shedding activity was examined using A. scoparius ovaries. Both AscRGP‐GR and AscRGP‐NH₂ induced oocyte maturation and ovulation in similar dose‐dependent manners. This is the first report on a C‐terminally amidated functional RGP. Collectively, these results suggest that AscRGP‐GR and AscRGP‐NH₂ act as a natural gonadotropic hormone in A. scoparius.     

Metamorphosin A is a neuropeptide

A novel biologically active peptide (metamorphosin A, MMA, pEQPGLW.NH₂) has recently been described. It was isolated from Anthopleura elegantissima and triggers metamorphosis in Hydractinia echinata. Antibodies directed against the C-terminal part of the molecule immunohistochemically stain neurosensory cells and processes in the anterior part of larvae of H. echinata. We assume that in metamorphosis MMA (or a closely related LW-amide) is an internal signal transmitted from the anterior to the posterior body parts. Immunoreactivity is also found in ectodermal nerve processes — but not cell bodies — in the tentacles and in the basal disk of the foot of Hydra magnipapillata. This is, to our knowledge, the first report of LW-amide(s) as (a) neuropeptide(s).     

Timecourse of oocyte development in saithe Pollachius virens

Wild caught North Sea saithe Pollachius virens were monitored for growth, sex steroid profiles and oocyte development pre‐spawning and measured for egg size and group fecundity during the spawning season in the laboratory. Vitellogenesis commenced in late October–early November, at a leading cohort size (C_L) of c. 250 µm, after which oocytes grew rapidly in size until spawning started in February. Notably, a distinct cortical alveoli stage was virtually absent with yolk granules observed in developing oocytes at the very beginning of vitellogenesis. Little atresia was observed pre‐spawning, but atretic re‐absorption of remnant oocytes containing yolk granules was found in all females immediately post‐spawning. As expected, concentrations of sex steroids, oestradiol‐17β (females), testosterone (both sexes) and 11‐ketotestosterone (both sexes), increased pre‐spawning before dropping post‐spawning. The present experiment provides the first validation of sex steroid levels in P. virens. Post‐ovulatory follicles were visible in histological sections from female gonads 9–11 months post‐spawning, but then disappeared. Spawning commenced around a C_L of c. 750 µm (700–800 µm). Hydrated oocytes (eggs) measured between 1·04 and 1·31 mm (mean = 1·18 mm) with decreasing sizes towards the end of spawning. The average estimated realized fecundity was c. 0·84 million eggs (median female total length, L_T = 60 cm). Spawning lasted from 13 February to 29 March.     

Altered cell wall properties are responsible for ammonium‐reduced aluminium accumulation in rice roots

The phytotoxicity of aluminium (Al) ions can be alleviated by ammonium (NH₄⁺) in rice and this effect has been attributed to the decreased Al accumulation in the roots. Here, the effects of different nitrogen forms on cell wall properties were compared in two rice cultivars differing in Al tolerance. An in vitro Al‐binding assay revealed that neither NH₄⁺ nor NO₃^? altered the Al‐binding capacity of cell walls, which were extracted from plants not previously exposed to N sources. However, cell walls extracted from NH₄⁺‐supplied roots displayed lower Al‐binding capacity than those from NO₃^?‐supplied roots when grown in non‐buffered solutions. Fourier‐transform infrared microspectroscopy analysis revealed that, compared with NO₃^?‐supplied roots, NH₄⁺‐supplied roots possessed fewer Al‐binding groups (‐OH and COO‐) and lower contents of pectin and hemicellulose. However, when grown in pH‐buffered solutions, these differences in the cell wall properties were not observed. Further analysis showed that the Al‐binding capacity and properties of cell walls were also altered by pHs alone. Taken together, our results indicate that the NH₄⁺‐reduced Al accumulation was attributed to the altered cell wall properties triggered by pH decrease due to NH₄⁺ uptake rather than direct competition for the cell wall binding sites between Al³⁺ and NH₄⁺.     

Tandem crystallization strategies for resolution of 3,3,3‐trifluorolactic acid [CF3CH(OH)COOH] by chiral benzylamines

Resolution of rac‐3,3,3‐trifluorolactic acid by diastereomeric salt formation was reinvestigated. The use of (S)‐1‐phenylethylamine gives coprecipitation of two diastereomeric phases, 1 (S)‐[NH₃CH(CH₃)Ph](S)‐[CF₃CH(OH)COO] and 2 (S)‐[NH₃CH(CH₃)Ph](R)‐[CF₃CH(OH)COO]·H₂O. Pure phase 1 may be obtained using molecular sieves as desiccants. Resolution by (S,S)‐2‐amino‐1‐phenylpropan‐1,3‐diol gives monoclinic (S,S)‐[NH₃CH(CH₂OH)CHOHPh] (R)‐[CF₃CH(OH)‐COO] 3 with minor (S)‐3,3,3‐trifluorolactate contamination, which is precluded in the recrystallized orthorhombic form 4 . A new resolution using inexpensive phenylglycinol gives pure phase 5 (S)‐[NH₃CH(CH₂OH)Ph] (S)‐[CF₃CH(OH)COO] in 76% yield, 94% ee in a single step, in preference to its (S)‐(R) diastereomer 6 . Overall efficient resolution for both enantiomers of the trifluorolactic acid (each ca. 70% yield, 99% ee) may be achieved by various two‐step “tandem” crystallizations, involving direct addition of either water or a second base to the filtrate from the initial reaction.     

Increase in intracellular cAMP is a prerequisite signal for initiation of physiological oocyte meiotic maturation in the hydrozoan Cytaeis uchidae

In medusae of the hydrozoan Cytaeis uchidae, oocyte meiotic maturation and spawning occur as a consequence of dark-light transition. In this study, we investigated the mechanism underlying the initiation of meiotic maturation using in vitro (isolated oocytes from ovaries) and in vivo (ovarian oocytes in medusae) systems. Injection of cAMP derivatives into isolated oocytes induced meiotic maturation in a dose-dependent manner. Meiotic maturation was also achieved in isolated oocytes preloaded with caged cAMP and exposed to UV irradiation. The caged cAMP/UV irradiation-induced meiotic maturation was completely inhibited by blockers of protein kinase A (PKA), H-89, KT5720, and Rp-cAMPS. The medusae from which most parts of the umbrella were removed (umbrella-free medusae) survived for at least 2 weeks, during which time oocyte meiotic maturation and spawning occurred. When H-89 and Rp-cAMPS were injected into ovarian oocytes of umbrella-free medusae within 3 min of dark-light stimulation, meiotic maturation was inhibited or delayed. An increase in intracellular cAMP was confirmed by FlCRhR, a fluorescent cAMP indicator, in ovarian oocytes exposed to dark-light transition as well as in isolated oocytes stimulated by caged cAMP/UV irradiation. These results indicate that the cAMP/PKA signaling pathway positively contributes to light-triggered physiological oocyte meiotic maturation in Cytaeis uchidae.     

Degradation of the Adriatic medusa <Emphasis Type="Italic">Aurelia</Emphasis> sp. by ambient bacteria

The decomposition of jellyfish after major bloom events results in the release of large amounts of nutrients, which can significantly alter nutrient and oxygen dynamics in the surrounding environment. The response of the ambient bacterial community to decomposing jellyfish biomass was evaluated in two marine ecosystems, the Gulf of Trieste (northern Adriatic Sea) and Big Lake (Mljet Island, southern Adriatic Sea). The major difference between these two ecosystems is that Aurelia sp. medusae occur throughout the year in the oligotrophic Big Lake, whereas in the mesotrophic Gulf of Trieste, they occur only seasonally and often as blooms. Addition of homogenized jellyfish to enclosed bottles containing ambient water from each of these systems triggered considerable changes in the bacterial community dynamics and in the nutrient regime. The high concentrations of protein, dissolved organic phosphorous (DOP), and PO₄ ³⁻ immediately after homogenate addition stimulated increase in bacterial abundance and production rate, coupled with NH₄ ⁺ accumulation in both ecosystems. Our preliminary results of the bacterial community structure, as determined with denaturing gradient gel electrophoresis, indicated differences in the bacterial community response between the two ecosystems. Despite divergence in the bacterial community responses to jellyfish homogenate, increased bacterial biomass and growth rates in both distinctive marine systems indicate potentially significant effects of decaying jellyfish blooms on microbial plankton.     

BAPTA‐AM dramatically improves maturation and development of bovine oocytes from grade‐3 cumulus‐oocyte complexes

Intracellular free calcium ([Ca²⁺]_i) is essential for oocyte maturation and early embryonic development. Here, we investigated the role of [Ca²⁺]_i in oocytes from cumulus‐oocyte complexes (COCs) with respect to maturation and early embryonic development, using the calcium‐buffering agent BAPTA‐AM (1,2‐bis[2‐aminophenoxy]ethane‐N,N,N′,N′‐tetraacetic acid tetrakis [acetoxymethyl ester]). COCs were graded based on compactness of the cumulus mass and appearance of the cytoplasm, with Grade 1 indicating higher quality and developmental potential than Grade 3. Results showed that: (i) [Ca²⁺]_i in metaphase‐II (MII) oocytes from Grade‐3 COCs was significantly higher than those from Grade‐1 COCs, and was significantly reduced by BAPTA‐AM; (ii) nuclear maturation of oocytes from Grade‐3 COCs treated with BAPTA‐AM was enhanced compared to untreated COCs; (iii) protein abundance of Cyclin B and oocyte‐specific Histone 1 (H1FOO) was improved in MII oocytes from Grade‐3 COCs treated with BAPTA‐AM; (iv) Ca²⁺ transients were triggered in each group upon fertilization, and the amplitude of [Ca²⁺]_i oscillations increased in the Grade‐3 group upon treatment with BAPTA‐AM, with the magnitude approaching that of the Grade‐1 group; and (v) cleavage rates and blastocyst‐formation rates were improved in the Grade‐3 group treated with BAPTA‐AM compared to untreated controls following in vitro fertilization and parthenogenetic activation. Therefore, BAPTA‐AM dramatically improved oocyte maturation, oocyte quality, and embryonic development of oocytes from Grade‐3 COCs.     

Time course of oocyte development in winter flounder Pseudopleuronectes americanus and spawning seasonality for the Gulf of Maine,Georges Bank and southern New England stocks

Winter flounder Pseudopleuronectes americanus were collected at monthly intervals from December 2009 to May 2011, to describe the pattern and seasonality of oocyte development, including: (1) the group‐synchronous transition from primary to secondary oocytes that initiates immediately after spawning, (2) the slow (months) development of vitellogenic oocytes followed by the rapid (weeks) maturation of oocytes, (3) the synchronous nature of mature oocytes ovulating, but the discrete releases of benthic eggs in batches, (4) the protracted (months) degradation of postovulatory follicles and (5) the occurrence of follicular atresia. Although fish were collected across only c. 2° latitudinal range, the spawning season was c. 1 month later in the Gulf of Maine (GOM) than on Georges Bank and in southern New England. This is probably due to lower temperatures in the GOM. These stock‐specific data regarding the time course of oogenesis are of practical value. This information is discussed in relation to measuring and interpreting elements of reproductive potential such as maturation, skipped spawning and fecundity, the response of reproductive traits by this widely distributed species to changing climate and the response by this common, marine‐estuarine species to urbanization, particularly environmental pollutants and dredging.     

Description of the ovarian follicle growth of the neotropical cichlids Petenia splendida and Parachromis managuensis (Perciformes: Cichlidae)

The ovarian follicle growth in Petenia splendida and Parachromis managuensis was analyzed. Both species presented analogous follicular growth, reaching similar values within the gonadosomatic and somatic indices (I_G) to those reported in other cichlids; however, with regard to maturity, these indices were significantly greater in Pe. splendida than in Pa. managuensis. The histology of oogenesis coincided with that known from most teleosts, except for one difference: the granulosa layer of Pa. managuensis was composed of pseudo‐stratified columnar cells, whereas other species presented columnar cells. Another conspicuous difference was registered in the first stage of oocyte maturation: Pa. managuensis exhibited the entire spectrum from primary to vitellogenic follicles, whereas in Pe. splendida only primary follicles occurred at that stage. It is concluded that Pa. managuensis shows a reproductive strategy with very short spawning periods, influencing the colonization capacity in the Grijalva‐Usumacinta River system. Both species, however, may still be considered as synchronic breeders, based on the characteristics of the maturation process of their oocytes despite their slightly different mode.     

Cryptic diets of forage fish: jellyfish consumption observed in the Celtic Sea and western English Channel

To establish if fishes’ consumption of jellyfish changes through the year, we conducted a molecular gut-content assessment on opportunistically sampled species from the Celtic Sea in October and compared these with samples previously collected in February and March from the Irish Sea. Mackerel Scomber scombrus were found to feed on hydrozoan jellyfish relatively frequently in autumn, with rare consumption also detected in sardine Sardina pilchardus and sprat Sprattus sprattus. By October, moon jellyfish Aurelia aurita appeared to have escaped predation, potentially through somatic growth and the development of stinging tentacles. This is in contrast with sampling in February and March where A. aurita ephyrae were heavily preyed upon. No significant change in predation rate was observed in S. sprattus, but jellyfish predation by S. scombrus feeding in autumn was significantly higher than that seen during winter. This increase in consumption appears to be driven by the consumption of different, smaller jellyfish species than were targeted during the winter.     

Reproductive biology of female striped marlin Kajikia audax in the western Pacific Ocean

Length and mass data for 1260 (536 females, 683 males, 41 sex unknown) striped marlin Kajikia audax were collected at the fish markets of Tungkang, Singkang and Nanfangao from July 2004 to September 2010. Of these samples, 534 gonads (236 females and 298 males) ranging from 95 to 206 cm in eye‐to‐fork length (L _EF ) and 8 to 88 kg in round mass (M _R), were collected. Chi‐square tests indicated sex ratios were homogeneous among months in 2004 and 2006–2008, but not in 2005, 2009 and 2010; and there were significant differences in sex ratio by size. The overall sex ratio (R _S ) differed significantly from the expected 0·5. Kajikia audax are sexually dimorphic and the proportions of females increased with size between 140 and 210 cm L _EF . Reproductive activity was assessed using a gonado‐somatic index (I _G ), external appearance of the gonads and histological examination and results indicated that the spawning season occurred from April to August with a peak in June to July. Based on histological observations and the distribution of oocyte diameters, K. audax are multiple spawners and their oocytes develop asynchronously. The estimated length‐at‐50% maturity (L _EF50 ) was c . 181 cm (c . 4·8 years of age) for females. The proportion of reproductively active females in the spawning season with ovaries containing postovulatory follicles (0·27) indicated that they spawned every 3·7 days on average. The hydrated oocyte method estimated mean ± S.D. batch fecundity (F _B ) to be 4·4 ± 2·02 million eggs; average relative fecundity was 53·6 ± 13·9 oocytes g^?1 M _R; and the average annual fecundity was 181·3 ± 48·3 million eggs. The parameters estimated in this study are key information for stock assessments of K. audax in the north‐western and central Pacific and will contribute to the conservation, management and sustainable yield of this species.     

Effects of structural analogues of nociceptin(1-13)NH₂ on brain antioxidant status in kainic acid-treated rats

The in vivo effects of nociceptin (N/OFQ(1–13)NH₂) and its structural analogues ([Dab⁹]N/OFQ(1–13)NH₂, [Dap⁹]N/OFQ(1–13)NH₂ and [Cav⁹]N/OFQ(1–13)NH₂) on the levels of lipid peroxidation and cell antioxidants (enzyme and non‐enzyme) in brain of control and kainic acid (KA)‐treated rats were studied. In control animals, [Dab⁹]N/OFQ(1–13)NH₂ and [Dap⁹]N/OFQ(1–13)NH₂, unlike N/OFQ(1–13)NH₂ and [Cav⁹]N/OFQ(1–13)NH₂, slightly increased the brain lipid peroxidation; the rest of the parameters were unchanged by all neuropeptides tested. KA (0.25 µg in 0.5 µl, i.c.v) increased the lipid peroxidation (4 and 24 h after KA‐injection) and decreased the glutathione level (1 h after KA‐administration). One hour after KA‐administration, the neuropeptides (2 µg in 0.5 µl, injected 30 min before KA) showed the following effects: a slight decrease in the KA‐induced lipid peroxidation by all nociceptin analogues and an enhancement of the KA‐decreased GSH level, but by [Cav⁹]N/OFQ(1–13)NH₂ only. The brain antioxidant enzyme activities were unchanged in all used experimental groups. In addition, the nociceptin analogues, especially [Can⁹]N/OFQ(1–13)NH₂, showed a good antioxidant capacity in chemical systems, generating reactive oxygen species. In conclusion, the substitution of lysin (Lys) in N/OFQ(1–13)NH₂ molecule with other amino acids might contribute to changes in its antioxidant properties. Copyright © 2011 John Wiley & Sons, Ltd.     

Life history characteristics and age validation of southern kingfish (Menticirrhus americanus (Linnaeus, 1758)) in the middle South Atlantic Bight

The purpose of this study was to determine critical components of the life history including otolith age validation, growth estimation, and reproductive characteristics for southern kingfish Menticirrhus americanus. A total of 2233 southern kingfish were collected from March 2009 to December 2010. Ages were estimated and validated using thin‐sectioned otoliths. Marginal increment analysis showed a single annulus was deposited once a year between April and May. Growth was significantly different (P < 0.0001) between sexes L_inf = 418.97 ± 16.58 mm, k = 0.29 ± 0.03, t₀ = ?1.30 ± 0.10 for females and L_inf = 290.74 ± 6.93 mm, k = 0.52 ± 0.05, t₀ = ?1.08 ± 0.11 for males. Southern kingfish spawn from March to August with a peak spawn in April. Based on evidence of multiple oocyte maturation stages and post‐ovulatory follicles (POFs) southern kingfish are multiple spawners exhibiting indeterminate fecundity. Spawning frequency for females ranging from 222 to 351 mm TL (age 1–5) was estimated as one spawning event every 2.0–4.2 days with up to 6 million total ova produced per spawning season per female.     

Angiotensin II, progesterone, and prostaglandins are sequential steps in the pathway to bovine oocyte nuclear maturation

Oocyte meiotic resumption is triggered by the ovulatory gonadotropin surge; in cattle, angiotensin II (AngII) and prostaglandins (PG) are key mediators of this gonadotropin-induced event. Here, we tested the hypothesis that progesterone (P₄) is also involved in oocyte meiotic resumption induced by the gonadotropin surge. In Experiment I, P₄ induced nuclear maturation in a dose-dependent manner using a coculture of follicular hemisections and cumulus-oocyte complexes. In the second experiment, using an in vivo model, an injection of mifepristone (MIFE; P₄ receptor antagonist) at the antrum of preovulatory follicles prevented GnRH-induced oocyte meiotic resumption in vivo. In Experiment III (coculture system similar to that of Experiment I), MIFE prevented stimulatory effects of AngII on resumption of meiosis, but saralasin (AngII receptor antagonist) did not inhibit P₄ actions. In Experiments IV and V, fibroblast growth Factor 10 (FGF10; known to suppress steroidogenesis in granulosa cells), blocked AngII-but not P₄-induced oocyte meiotic resumption. Therefore, we inferred that AngII is upstream to P₄ in a cascade to induce meiotic resumption. Previously, we had reported that AngII acted throughout the PGs pathway to modulate nuclear progression. In Experiment V, indomethacin inhibited resumption of meiosis induced by P₄, providing further support to the AngII-P₄ sequential effect on meiotic resumption. In conclusion, we inferred that AngII, P₄ and PGs are sequential steps in the same pathway that culminates with bovine oocyte maturation.     

DFP-sensitive multicatalytic protease complexes (proteasomes) involved in the control of oocyte maturation in the toad,Bufo japonicus

The inhibition of progesterone-induced oocyte maturation by diisopropylfluorophosphate (DFP), a typical serine protease inhibitor, was investigated in oocytes of the Japanese toad Bufo japonicus for the first time. Oocytes to which DFP was externally applied did not undergo germinal vesicle breakdown (GVBD), which is an early signal of oocyte maturation, in response to progesterone. The more inhibitory period was found to be 0–0.5 GVBD₅₀ on a relative time scale [when the time at which 50% of the oocytes had completed GVBD (GVBD₅₀) was set at 1.0], namely, before the beginning of GVBD. DFP-sensitive proteases, which seem to be multifunctional nonlysosomal protease complexes (proteasomes), may already be present in the cytosol of premature oocytes. Peptide hydrolyzing activity, as reflected by proteasome activity, was found to be regulated before and after GVBD. In addition, immunoblotting regarding the native electrophoretic protein profile of the proteasomes throughout the maturational process demonstrated that they undergo alterations in mobility dependent upon the maturational process. These findings raise the possibility that the activities of some endogenous DFP-sensitive proteasomes play distinct, essential roles in oocyte maturation triggered by progesterone in Bufo. © 1994 Wiley-Liss, Inc.     

Goosefish Lophius americanus fecundity and spawning frequency,with implications for population reproductive potential

To improve knowledge of goosefish Lophius americanus' reproductive biology, females were collected during 2009–2012 from the Mid‐Atlantic Bight shelf region of the U.S. east coast. Batch fecundity increased with total length (L_T), from 229 100 to 2 243 300 mature oocytes per female (L_T range: 55·5–112 cm; n = 54). This estimate of fecundity at L_T is lower than one derived from a sample collected during 1982–1985. Examination of whole oocyte diameters in different months indicated that L. americanus is a serial spawner, releasing more than one egg veil per spawning season, as suspected or observed for other Lophius species. Seasonality of spawning was evident from whole oocytes and gonad histology, and from larval fish surveys spanning the U.S. north‐east shelf, and confirmed a protracted (c. 6 months) spawning period. Peak spawning activity progressed northward from spring to autumn. The population‐level implications of these results were explored by estimating population reproductive potential (P_RP), which considered the value of both current and future per capita reproduction using decade‐specific age structure and fecundity at length. P_RP is now more than 50% lower compared with the historical period (1982–1985), a result of the lower proportions of large females and reduced fecundity across all sizes. Mechanisms that could explain this loss of stock productivity are fishing‐induced size–age truncation or regime shifts in egg production caused by changes in energy density of common forage species.     

Comparative proteome analysis of porcine follicular fluid and serum reveals that excessive α2‐macroglobulin in serum hampers successful expansion of cumulus‐oocyte complexes

Porcine follicular fluid (pFF) constitutes the micro‐environment of the maturing oocyte. Although pFF is a transudate of serum, in pigs, it is superior to serum in promoting in vitro expansion of the cumulus cells, a specialized cell population surrounding the oocyte. A comparative proteome analysis of autologous serum and pFF was performed to investigate proteins involved in successful cumulus expansion of porcine oocytes. iTRAQ labeling followed by 2‐D LC ESI‐Q‐TOF MS/MS revealed 63 proteins common to both fluids of which the abundance of 13 proteins was significantly different (p<0.05). Seven proteins were more concentrated in serum whereas six proteins were more abundant in pFF. To investigate the importance of these proteins, the cumulus matrices of COCs were collected after in vitro maturation in media supplemented with either of both biologically fluids and then subjected to 2‐D PAGE analysis. α₂‐Macroglobulin and CH4 and secrete domains of swine IgM, which were both less abundant in pFF, were absent from cumulus matrix extracts after in vitro maturation in pFF. Although both proteins were incorporated in the matrices of cumulus‐oocyte complexes matured in serum, depletion of α₂‐macroglobulin from serum could significantly compensate for the impaired cumulus expansion of oocytes matured in serum.