Lipid and fatty acid content in wild white seabream (Diplodus sargus) broodstock at different stages of the reproductive cycle

The lipid and fatty acid content of the gonads, liver and muscle of wild white seabream males and females was studied at different stages of the reproductive cycle. Samples were taken from mature white seabream at pre-spawning (November), mid-spawning (March) and post-spawning (June) stages. The results showed that lipid accumulates in gonads and muscle from November to March. The gonadosomatic index (GSI) was also increased during this period. Male gonads showed a greater increase in polar lipid (PL) than neutral (NL), while female gonads displayed the reverse. The increase in both neutral and polar lipid was higher in the muscle of males than in females. In the same period, male livers showed no changes either in lipid content or the hepatosomatic index (HSI), while female livers registered an increase in both lipid content and HSI. Between March and June, in both males and females, total, neutral and polar lipid decreased sharply in the gonads and muscle. Muscular lipid content reduction was more pronounced in males than females. On the other hand, the lipid content of the liver in males and females remained relatively constant. In general terms, the amounts of major fatty acids (16:0, 18:1n-9, 20:5n-3 and 22:6n-3) in gonadal and muscular polar and neutral lipid in both males and females increased from November to March and declined thereafter. Variations of the liver fatty acid content were less extreme. In the period from mid-spawning to post-spawning, the presence of 20:4n-6 in polar and neutral lipid increased to a notable extent in all organs studied.     

Cell cooperation in coelomocyte cytotoxic activity of Paracentrotus lividus coelomocytes

The coelomic fluid from the sea urchin Paracentrotus lividus contains several coelomocyte types including amoebocytes and uncoloured spherulocytes involved in immune defences. In the present paper, we show a Ca(2+)-dependent cytotoxic activity for the unfractionated coelomocytes assayed in vitro, with rabbit erythrocytes and the K562 tumour cell line. In a plaque-forming assay, whole coelomocyte preparations as well as density gradient separated coelomocyte populations revealed that cell populations enriched in uncoloured spherulocytes, exerted high cytotoxic activity by releasing lysins in the presence of amoebocytes. This cooperative effect could be dependent on soluble factors released by amoebocytes. With regard to this, we show that an enhanced cytotoxic activity was found by adding the supernatant from sonicated amoebocytes or hemocyte culture medium into spherulocyte preparations.     

Cellular anamnesis in earthworms

The quantitative response of coelomic cells associated with first- and second-set Eisenia xenografts transplanted to Lumbricus hosts at 20 ° C was compared with autografts and nonspecific wounds. Coelomocyte numbers were significantly lower in response to first than second-set xenografts. Coelomocytes also increased in association with autografts and nonspecific wounds, but the reaction is short lived, and essential for early wound healing and repair. Such nonspecific increases are different from subsequent specific immunologic longer-lasting coelomocyte responses. First-set xenografts induced a relatively slow increase in coelomocytes, which declined after 3–4 days postgrafting. By contrast, second-set xenografts caused an accelerated rise in coelomocytes, usually 20 to 30% greater than the maximum coelomocyte response induced by first-set xenografts. The mean survival time for first-set xenografts (non-self) was 17 ± 1 days, but repeat second-sets were rejected in an accelerated time of 6 ± 1 days. Autografts (self) are never destroyed. After priming with a first-set xenograft, this heightened coelomocyte reaction, to a second-set xenograft, was interpreted as an anamnestic response. The memory response is measurable in two ways: grossly as accelerated rejection of repeat xenografts, and at the cellular level, heightened coelomocyte numbers. Specific cellular immunity is demonstrable phylogenetically at the level of annelid worms.     

Immune Challenge and Pre- and Post-copulatory Female Choice in the Cricket Teleogryllus commodus

Life history theory predicts a trade off between the expression of male sexual traits and the immune system. To test for this trade off, male crickets Teleogryllus commodus were injected with bacterial lipopolysaccharides (LPS) to induce an immune response and their subsequent pre- and post-copulatory sexual attractiveness to virgin and non-virgin females was assessed. Pre-copulatory attractiveness was quantified based on the time taken for males to court and mate with a female. Post-copulatory attractiveness was measured as the time that elapsed between mating and a female interrupting sperm transfer by removing the externally attached spermatophore. We found no difference in pre- or post-copulatory attractiveness between LPS and control males. In contrast, virgin females retained spermatophores for almost twice as long as non-virgins, presumably to enhance fertilization and begin egg-laying. Finally, we note that although LPS is a widely used immune elicitor in insects, its effect might be transitory. After 24 h there was no detectable elevation in haemolymph antibacterial activity of LPS injected crickets compared to that of controls.     

Evidence for male alternative reproductive tactics in convict cichlids (<Emphasis Type="Italic">Amatitlania siquia</Emphasis>) in Lake Xiloá, Nicaragua

We present evidence suggesting that some male convict cichlids (Amatitlania siquia) in Lake Xiloá, Nicaragua engage in alternative reproductive tactics (ARTs). These putative ART males were smaller than typical parental males, displayed coloration similar to breeding females, and possessed enlarged gonads. Gonadosomatic indices in these males were 16-fold higher than parental males and three-fold higher than females. This phenotype is consistent with the ‘sneaker’ or ‘satellite’ phenotype reported in other species. A survey of 282 fish in 2014 found three males (1% of all fish, 2% of males) with these characteristics. This finding is significant because convict cichlids are frequently studied in laboratory and field in the context of monogamy and biparental care.     

Accumulation of the major yolk protein and zinc in the agametogenic sea urchin gonad

Sea urchins of both sexes store the nutrients necessary for gametogenesis in nutritive phagocytes of the agametogenic gonad. A zinc-binding protein termed the major yolk protein (MYP) is stored here as two isoforms: the egg-type (predominant in egg yolk granules) and the coelomic fluid-type (a precursor with greater zinc-binding capacity). MYP is used during gametogenesis as material for synthesizing gametic proteins and other components. We investigated its accumulation and relationship to zinc contents in gonads during the non-reproductive season in Pseudocentrotus depressus. MYP constituted most of the protein in coelomic fluid and gonads. Both ovaries and testes grew gradually, accumulating MYP and zinc during the year. Total zinc contents and the ratio of coelomic fluid-type to egg-type protein were higher in ovaries than in testes as gametogenesis approached. Most of the zinc in the coelomic fluid was bound to MYP, and the concentrations of MYP and zinc were elevated toward the onset of oogenesis in the female coelomic fluid. Thus, MYP accumulates in the agametogenic ovaries and testes during the non-reproductive season, playing a role as a carrier to transport zinc to the gonad. Transportation of zinc by MYP is more active in females than in males.     

Sexually dimorphic immune response in the harem polygynous Wellington tree weta Hemideina crassidens

Abstract Adult males are often less immunocompetent than females. One explanation for this is that intense sexual selection causes males to trade‐off investment in immunity with traits that increase mating success. This hypothesis is tested in the Wellington tree weta (Hemideina crassidens), a large, sexually dimorphic orthopteran insect in which males possess enormous mandibular weaponry used during fights for access to female mates. Field‐collected males have a significantly greater immune response (greater melanotic encapsulation) than females, suggesting that body condition, longevity or an allied trait is important to male fitness, or that females require materials for egg production that would otherwise be used to boost immunity. Although immunity is expected to trade‐off against reproductive traits in both sexes, there is no significant relationship between immune response and weapon or testes size in males, nor fecundity in females.     

Dexamethasone treatment in vitro resulted in different responses of two fractions of phagocytes of the holothurian Eupentacta fraudatrix

Echinoderm phagocytes are considered to be analogues to vertebrate macrophages. Previously, the phagocytes of some echinoderm species were divided into two fractions with unclearly identified functional properties. This study aims at modeling the immune response of two phagocyte fractions (P1 and P2) of the holothurian Eupentacta fraudatrix to the synthetic glucocorticoid hormone dexamethasone (Dex) in vitro and at comparison of the effects of such pretreatment on humoral cooperation of each phagocyte fraction with another type of immunocytes, morula cells. During 48-h incubation, Dex (0.1–100 μM) induced apoptosis in a direct (in the P1 fraction) or reverse (in the P2 fraction) concentration-dependent manner. In addition, 100 μM Dex differently affected the cytokin-like substance level in the P1 and P2 phagocyte fractions. Moreover, the supernatants of the Dex(100 μM)-pretreated phagocytes induced opposite changes in the IL-1-like substance level in morula cells. These results indicate a striking functional difference between the two phagocyte fractions. The data obtained provide a new insight into the evolution of macrophage response and into the prospects of the use of in vitro holothurian phagocyte model.     

Modulation of behavior in zebrafish,Danio rerio,according to female reproductive status and visual and chemical cues

Zebrafish, Danio rerio, is one of the most studied vertebrate models. However, there are still many aspects of its reproductive behavior to be elucidated. The aim of this work was to clarify whether males and females of this species display different behaviors according to sexual status, and the kind of cues they were exposed to (visual and/or chemical). Females in two different sexual status, pre- (PreS) or post-spawning (PostS), were exposed to single males cues (visual or chemical) or complementary cues (visual and chemical together). PreS females spent more time near the male’s compartment than PostS when they were exposed to complementary cues, but no differences were found when only one cue was present. Males showed a higher proximity to females when they were exposed to visual, and both cues together, but no difference was found according to females’ reproductive status. When no barrier was present, males and PreS females spent more time swimming together than males with PostS females. These results showed that females’ reproductive status, and the kind of cues to which females and males are exposed to, can modulate behaviors related to reproduction. Particularly, both cues together (visual and chemical) are necessary to trigger different behaviors in females according to their reproductive status.     

Sex-Related Effects of Reproduction on Biomarkers of Oxidative Damage in Free-living Barn Swallows (Hirundo rustica)

According to life-history theory, the allocation of limiting resources to one trait has negative consequences for other traits requiring the same resource, resulting in trade-offs among life-history traits, such as reproduction and survival. In vertebrates, oxidative stress is increasingly being considered among the physiological mechanisms forming the currency of life-history trade-offs. In this study of the barn swallow (Hirundo rustica), we focus on the oxidative costs of reproduction, especially egg laying, by investigating the effects of breeding stage (pre- vs. post-laying) and progression of the season on three biomarkers of oxidative damage (OD) to plasma proteins, namely the concentration of malondialdehyde (MDA)-protein adducts and of protein thiol groups (PSH), and the protein carbonyl (PCO) content. Moreover, we investigated whether males and females differed in plasma OD levels, because the inherent sex differences in reproductive roles and physiology may originate sex-specific patterns of OD during breeding. We found that MDA-protein adduct levels were higher in the pre-laying than in the post-laying phase, that males had lower levels of MDA-modified proteins than females, and that the decline of MDA-protein adduct concentration between the pre- and the post-laying phase was more marked for females than males. In addition, MDA-protein adduct levels declined with sampling date, but only during the pre-laying phase. On the other hand, plasma PCO levels increased from the pre- to the post-laying phase in both sexes, and females had higher levels of PCO than males. PSH concentration was unaffected by breeding stage, sex or sampling date. On the whole, our findings indicate that biomarkers of protein oxidation closely track the short-term variation in breeding stage of both male and female barn swallows. Moreover, the higher protein OD levels observed among females compared to males suggest that egg laying entails oxidative costs, which might negatively affect female residual reproductive value.     

Pathways and places associated with nonindigenous aquatic species introductions in the Laurentian Great Lakes

The present study aimed to evaluate the health status of Octopus maya females on different days after spawning (days 0, 10, 20, 30, and 40). A total of 25 O. maya females were examined in terms of physiological (i.e., weight loss, hepatosomatic and gonadosomatic indexes, and hemocyanin, protein, glucose, cholesterol, and acylglycerides concentrations in plasma) and immunological variables (i.e., total hemocyte count, hemagglutination, and phenoloxidase activity). We hypothesized that O. maya females should maintain their physiological integrity throughout the post-spawning period until the hatching of the offspring. Results showed that the physiological and immunological indicators measured in post-spawning females significantly changed with time. Loss of body weight over time and a decrease in the hepatosomatic and gonadosomatic indexes were observed. Hemolymph components showed variations that reflect the consumption of reserves and coincide with an increased immune process of hemagglutination and phenoloxidase activity in hemocytes. Our results demonstrate that O. maya females are adapted to maintain an adequate state of health to care for their spawn despite the long period of starvation and contribute to the identification of the mechanisms involved in maintaining the integrity of these animals during one of the most critical phases of their life cycle.     

Growth and sexual strategies in the fishThalassoma duperrey (Labridae), a protogynous hermaphrodite

Synopsis Adults of the fishThalassoma duperrey, a protogynous hermaphrodite, were collected and growth observed in captivity to study the relationship between growth and reproduction among primary males, females, and secondary males. Sexual maturity is reached at about 60 mm standard length, probably less than 1 year after fertilization. Gonosomatic index in both males and females peaks at about 120 mm, nearly 2 years later. Shortly thereafter females typically change sex, and both primary and secondary males undergo color change. At the same time gonosomatic index falls abruptly and remains low in large fish. The above changes appear to reflect differences in reproductive effort over a lifetime and are interpreted as the optimum strategy given the social and mating system of this fish. Unless they cannot acquire enough food to develop large gonads, small individuals put a much greater proportion of energy into growth than reproduction apparently to minimize the period of low fitness. Intermediate-sized males and females generally invest heavily in gametes, though some retain small gonads. Large individuals (both primary and secondary males) greatly reduce their investment in gametes, probably trading the energy required to maintain reproductive territories for it. This kind of gonad ontogeny involving gonad regression, as inT. duperrey and other labrid fishes, is unique among vertebrates.     

Comparative immunological analysis of echinoderm cellular and humoral defense factors

Coelomocyte are found in the fluid filling coelomic cavity of echinoderms and depending on species can be a mixture of several morphologically different types. There are among them: granular and agranular amoebocytes, morula cells, vibratile and lymphocyte-like cells. All these cells take part in cellular response to immune challenges through phagocytosis, clotting, encapsulation of foreign particles, cytotoxicity, and the production of antimicrobial agents, such as reactive oxygen and nitric oxide. The data are given on a variety of humoral factors found in the coelomic fluid, including different types of lectines, agglutinins, hemolysins, acute phase proteins and antimicrobial factors. The discussion on cooperation between cellular and humoral arms of defense reactions during inflammation reveals the crucial role of coelomocytes in immune response. It is suggested that the sea urchin complement system (that is homologous to the alternative pathway in vertebrates) is appeared initially in echinoderms as a protein cascade that points to opsonization of foreign cells and particles, augmenting their phagocytosis and subsequent destruction by coelomocytes. So the identification of a simple complement system as a part of the echinoderm immune response shows that these animals as well as all invertebrate deuterostomes share innate immune system homologies with vertebrates. Studying the simpler immune response demonstrated by echinoderms is important for understanding the ancestral deuterostome defense system and reconstructing the evolution of immune system in higher vertebrates.     

Litter quality and inflammatory response are dependent on mating strategy in a reptile

Maintenance of health and the production of offspring are competing processes that can result in trade-offs. As vertebrates invest substantial resources in their immune system, it is crucial to understand the interactions between immunity and reproductive strategies. In the lizard Zootoca vivipara, females have condition- and context-dependent mating strategies. We predicted that, if the risk of infection is higher for polyandrous females, then polyandrous females should invest more in immune system while monandrous females should invest more in reproduction. In order to test our prediction, we captured 62 gravid females of known age in a natural population; we kept them until parturition to access to their offspring. Then, using microsatellite marker-based paternity analyses within litters, we determine the mating strategy of females (monandrous or polyandrous). Females were also challenged with PHA to estimate their inflammatory response. Our results show that polyandrous females have a higher PHA response than the monandrous females, and that monandrous females produce more males and more juveniles of better body condition than polyandrous females. The relationship between mating behaviour and immune function may have consequences for females and may shape the evolution of mating systems.     

A test of the haploid susceptibility hypothesis using a species with naturally occurring variation in ploidy

The haploid susceptibility hypothesis (HSH) was proposed as an explanation for how behavioral roles in haplodiploid social systems evolved. It posits that haploid males are more susceptible to disease than diploid females due to decreased genetic variability at key disease resistance loci. The resulting decreased immunocompetence is hypothesized to have played a role in the evolution of social behavior by limiting the behavioral repertoire haploids perform. Here, we test this hypothesis in a study system that separates ploidy from behavioral sex roles: Polistes dominulus, a social wasp, has colonies with naturally occurring diploid males. We report results from two immune function assays—hemolymph phenoloxidase activity and encapsulation response—performed on haploid males, diploid males, and diploid females. Our data suggest that ploidy is not a significant contributor to immune function in P. dominulus; thus, our data do not support the HSH for the evolution of behavioral roles. Instead, our data indicate that time of emergence is the best predictor of immune function in Polistes. We speculate that seasonal trends result from seasonal differences in pathogens and parasites.     

Gonadal state of wild amphioxus populations and spawning success in captive conditions during the breeding period in Japan

Adult individuals of amphioxus (Branchiostoma belcheri) were collected by dredging from a research vessel at selected stations in two areas off the coast of Japan in July 2000: Deyama and Takamatsu so named by local fishermen in the Enshu Nada Sea. The number of males collected exceeded that of females at all the stations in Takamatsu and at four of five stations in Deyama. The over all sex ratio (males : females) of the collected animals was 1.2 : 1. The animals showed various maturational stages of the gonad, and approximately 70% had mature gonads. However, post-spawning animals were identified only at two stations in Takamatsu. Mature animals were placed in laboratory tanks. These animals remained in good conditions for about two months, and many animals spontaneously spawned in the tanks. This is the first report of spontaneous spawning of B. belcheri in Japan.     

Inbreeding and extreme outbreeding cause sex differences in immune defence and life history traits in Epirrita autumnata

Empirical studies in vertebrates support the hypothesis that inbreeding reduces resistance against parasites and pathogens. However, studies in insects have not found any evidence that inbreeding compromises immune defence. Here we tested whether one generation of brother-sister mating or extreme outbreeding (mating between two populations) have an effect on innate immunity and life history traits in the autumnal moth, Epirrita autumnata. We show that the effect of inbreeding on immune response differed between the sexes: whereas in females, inbreeding significantly reduced encapsulation response against nylon monofilament ability, it did not have a significant effect on male immune response. There were also differences in the correlation of the immune response with other traits: in females increased immune response was positively correlated with large size, whereas in males immune response increased with a reduction in development time. Immune response differed significantly among families in males but not in females, both for the inbreeding and extreme outbreeding experiments. In conjunction with the observed immune responses to inbreeding, these data suggest that in males genetic variation for immune response is largely additive or non-directional with respect to dominance, whereas in females variation is much reduced and consists of directional dominance variance. Further, we show that encapsulation response against nylon monofilament is associated with the resistance against real pathogens suggesting that this widely used method to measure the strength of immune defence in insects is also a biologically relevant method.     

Sex differences in contaminant concentrations of fish: a synthesis

A comparison of whole-fish polychlorinated biphenyl (PCB) and total mercury (Hg) concentrations in mature males with those in mature females may provide insights into sex differences in behavior, metabolism, and other physiological processes. In eight species of fish, we observed that males exceeded females in whole-fish PCB concentration by 17 to 43 %. Based on results from hypothesis testing, we concluded that these sex differences were most likely primarily driven by a higher rate of energy expenditure, stemming from higher resting metabolic rate (or standard metabolic rate (SMR)) and higher swimming activity, in males compared with females. A higher rate of energy expenditure led to a higher rate of food consumption, which, in turn, resulted in a higher rate of PCB accumulation. For two fish species, the growth dilution effect also made a substantial contribution to the sex difference in PCB concentrations, although the higher energy expenditure rate for males was still the primary driver. Hg concentration data were available for five of the eight species. For four of these five species, the ratio of PCB concentration in males to PCB concentration in females was substantially greater than the ratio of Hg concentration in males to Hg concentration in females. In sea lamprey (Petromyzon marinus), a very primitive fish, the two ratios were nearly identical. The most plausible explanation for this pattern was that certain androgens, such as testosterone and 11-ketotestosterone, enhanced Hg-elimination rate in males. In contrast, long-term elimination of PCBs is negligible for both sexes. According to this explanation, males not only ingest Hg at a higher rate than females but also eliminate Hg at a higher rate than females, in fish species other than sea lamprey. Male sea lamprey do not possess either of the above-specified androgens. These apparent sex differences in SMRs, activities, and Hg-elimination rates in teleost fishes may also apply, to some degree, to higher vertebrates including humans. Our synthesis findings will be useful in (1) developing sex-specific bioenergetics models for fish, (2) developing sex-specific risk assessment models for exposure of humans and wildlife to contaminants, and (3) refining Hg mass balance models for fish and higher vertebrates.