A Correlation Between Pituitary and Integumentary Structure in the Nine-Spined Stickleback,Pungitius pungitius L.

Benjamin, M. 1980. A correlation between pituitary and integumentary structure in the nine-spined stickleback, Pungitius pungitius L. (Department of Anatomy, University College, Cardiff, Wales, U.K.) — Acta zool. (Stockh.) 61(2): 105–109. Naturally occurring, large pituitary cysts, that almost excluded prolactin cells from the pituitary of Pungitius pungitius L., offered a unique opportunity to study a target organ for prolactin (the integument) in fish that were “partially hypophysectomised” without any accompanying surgical trauma. In fish with large pituitary cysts, the epidermis from the lateral body wall was thinner and its mucocytes less abundant, than in fish with normal pituitaries and thus many prolactin cells. In support of the hypothesis that prolactin produced the observed integumentary changes, was the similarity of other pituitary cells in animals with and without cysts. Evidently, prolactin can influence the integument of Pungitius, even though it does not seem essential for freshwater survival.     

Geographic Variation in Age Structure and Longevity in the Nine-Spined Stickleback (Pungitius pungitius)

Variation in age and size of mature nine-spined sticklebacks (Pungitius pungitius) within and among 16 Fennoscandian populations were assessed using skeletochronology. The average age of individuals in a given population varied from 1.7 to 4.7 years. Fish from pond populations were on average older than those from lake and marine populations, and females tended to be older than males. Reproduction in marine and lake populations commenced typically at an age of two years, whereas that in ponds at an age of three years. The maximum life span of the fish varied from 3 to 7 years. Mean body size within and among populations increased with increasing age, but the habitat and population differences in body size persisted even after accounting for variation in population age (and sex) structure. Hence, the population differences in mean body size are not explainable by age differences alone. As such, much of the pronounced intraspecific variation in population age structure can be attributed to delayed maturation and extended longevity of the pond fish. The results are contrasted and discussed in the context of similar data from the three-spined stickleback (Gasterosteus aculeatus) occupying the same geographic area.     

Parasites of the nine-spined stickleback Pungitius pungitius (L)

Eleven species of parasite are reported from the nine-spined stickleback Pungitius pungitius (L). Nine of these, namely, Trichodina domerguei, T. tenuidens, Vorticella sp., Epistylis?, Diplostomum spathaceum, Cryptocotyle lingua, Proteocephalus filicollis, Schistocephalus solidus and glochidia of Anodonta cygnea, are new host records for Great Britain. Gyrodactylus spp. and Thersitina gasterostei were also found.     

The origin of pituitary cysts in the rostral pars distalis of the nine-spined stickleback,Pungitius pungitius L.

Summary Pituitary cysts in the nine-spined stickleback, Pungitius pungitius L., develop next to blood vessels passing through the prolactin zone of the rostral pars distalis to the connective tissue capsule at its periphery. Cysts were most frequent when pituitaries were large compared with body lengths. However, the incidence of cysts could not be closely related to body length alone. As the rostral pars distalis is more highly vascularised in fish with large pituitaries, and as there was no evidence of accumulating secretion around these blood vessels, it is suggested that cysts develop when vascular demands (or supplies) become excessive. Associated with the greater vascularity of the rostral pars distalis in large pituitaries was a remarkable development of non-granulated cells. Indeed cysts may originate as enlarged intercellular spaces between such cells, as the latter often surround blood vessels. The non-granulated cells are also important in enlarging cyst cavities (by phagocytosing prolactin-cell debris) and perhaps for maintaining their structural integrity. It is suggested that the macrophages within cyst cavities are derived from the non-granulated cells.     

Carotenoids in fish. XXVI. Pungitius pungitius (L.) and Gasterosteus aculeatus L. (Gasterosteidae)

The author investigated the presence of various carotenoids in the different parts of the body of Pungitius pungitius (L.) and Gasterosteus aculeatus L. by means of columnar and thin-layer chromatography. The investigations revealed the presence of the following carotenoids:

in Pungitius pungitius. α-carotene, β-carotene, β-cryptoxanthin, mutatochrome, zeaxanthin and astaxanthin;

in Gasterosteus aculeatus: β-carotene, β-cryptoxanthin, β-carotene epoxide, neothxanthin, canthaxanthin, mutatochrome, lutein, phoenicoxanthin, zeaxanthin, taraxanthin, tunaxanthin, astaxanthin, astaxanthin ester and α-doradexanthin. The total carotenoid content ranged from 2.229 to 138.504 µg/g wet weight.

     

Quantitative trait loci for growth and body size in the nine‐spined stickleback Pungitius pungitius L.

Body size is an ecologically important trait shown to be genetically variable both within and among different animal populations as revealed by quantitative genetic studies. However, few studies have looked into underlying genetic architecture of body size variability in the wild using genetic mapping methods. With the aid of quantitative trait loci (QTL) analyses based on 226 microsatellite markers, we mapped body size and growth rate traits in the nine‐spined stickleback (Pungitius pungitius) using an F₂‐intercross (n = 283 offspring) between size‐divergent populations. In total, 17 QTL locations were detected. The proportion of phenotypic variation explained by individual body size‐related QTL ranged from 3% to 12% and those related to growth parameters and increments from 3% to 10%. Several of the detected QTL affected either early or late growth. These results provide a solid starting point for more in depth investigations of structure and function of genomic regions involved in determination of body size in this popular model of ecological and evolutionary research.     

Comparative ultrastructural studies on the prolactin cells in the pituitary of nine-spined sticklebacks,Pungitius pungitius L., with and without adenohypophyseal cysts

Summary The ultrastructure of the prolactin cells in nine-spined sticklebacks (Pungitius pungitius L.) with and without large pituitary cysts was compared. Prolactin cells from animals with cysts were less active as regards hormone synthesis and release than those from animals without cysts. Rough endoplasmic reticulum, mitochondria, Golgi apparatus and exocytotic figures were all more prominent in animals without cysts. Lysosomes and mature secretory granules were more plentiful in animals with cysts. The correlation between inactive prolactin cells and pituitary cysts argues against the hypothesis that cysts store prolactin released by holocrine secretion. It is more likely that the origin of cysts from degenerating cells signals extreme inactivity in the rostral pars distalis.     

Lactate dehydrogenase isozymes and allozymes of the nine-spined stickleback Pungitius pungitius (L.) (Osteichthyes: Gasterosteidae)

Zymograms indicate the existence of three loci coding for lactate dehydrogenase in the nine-spined stickleback Pungitius pungitius. The skeletal muscle locus is polymorphic for two codominant alleles: Ldh-A(100). and Ldh-A(140). Differences in allele frequencies among nine samples, obtained from eight geographically isolated populations, proved not significant in 28/36 pairwise comparisons. The frequency of Ldh-A(100) varied from 0.426 to 0.715. Significant differences in apparent Km (pyruvate) values were found among the LDH-A allozymes suggesting a functional basis for the selective maintenance of this polymorphism.     

Factors influencing the stability of nutrient-enriched freshwater macrophyte communities: the role of sticklebacks Pungitius pungitius and freshwater snails

1. Enclosures, with the following characteristics, were used to investigate the effects of increased nutrient (nitrate and phosphate) loading on freshwater communities: (a) controls with normal densities of invertebrates, and including macrophytes, molluscs and fish (sticklebacks), and communities similar to the controls but with (b) much reduced snail densities and (c) increased fish densities. 2. The addition of nutrients resulted in increases in the biomass of phytoplankton and epiphyton, as well as zooplankton counts, in all the experimental enclosures. 3. A reduction in the snail population density resulted in a significant decrease in phytoplankton density and an increase, compared to controls, in the density of epiphytic algae growing on the leaves of the submerged macrophytes, Potamogeton crispus and Groenlandia densa. It also resulted in a significant increase (3.5 times that in the controls) in chlorophyll-a values of epilithic algae growing on glass slides, an increase in senescent tissue in macrophytes and a decline in the mass of Groenlandia densa by the end of the experiment. 4. An increase in the fish population resulted in a significant decline, compared to the controls, in the densities of zooplankton (including Chydorus sphaericus and copepods), Lymnaea peregra (from May to mid-June), Asellus meridianus, Crangonyx pseudagracilis, Culex (P.) molestus and Physa fontinalis. It also resulted in a change in the composition of the phytoplankton, with an increase in the large colonial Eudorina elegans and a decline in smaller planktonic algae, including Ankistrodesmus and Cryptomonas spp. 5. The possible mechanisms responsible for the effects are evaluated and their relevance to conservation and management of freshwater macrophyte communities are discussed.     

Some effects of low oxygen tensions on the distribution of the three-spined stickleback Gasterosteus aculeatus L. and the nine-spined stickleback Pungitius pungitius (L.)

During extensive sampling of populations of sticklebacks for parasites, it became apparent that marked differences existed in the distribution of the 2 British freshwater species. Observation of the survival, respiratory rates and distribution of three- and nine-spined sticklebacks from a variety of habitats supports the suggestion that physiologically, the nine-spined stickleback is much better adapted to life in closed, shallow, weedy, eutrophic waters, depleted in oxygen. By comparison, Gasterosteus aculeatus favours more open well oxygenated water.     

A Redescription of the Cestodes Proteocephalus filicollis (Rudolphi) from Gasterosteus aculeatus L., and P. ambiguus (Dujardin) from Pungitius pungitius (L.)

Based on material from two stickleback species living in the same biotope, Proteocephalus filicollis (Rudolphi, 1802) and Proteocephalus ambiguus (Dujardin, 1845) are regarded as two distinct species. The most useful character for their discrimination is the presence and absence of an apical scolex of P. filicollis and P. ambiguus , respectively. Furthermore, transverse sections revealed that the longitudinal muscles consist of approximately 5 layers of muscle fibres in P. filicollis , as opposed to a single layer in P. ambiguus . The two species differ also in total length, width, number of segments and in the state (progress) of maturation of the proglottids along the strobila.     

Changes in the mucous cells of the gills, buccal cavity and epidermis of the nine-spined stickleback, Pungitius pungitius L., induced by transferring the fish to sea water

A histochemical analysis of mucous cells in the gills, buccal cavity and epidermis of the nine-spined stickleback, Pungitius pungitius L., using alcian blue and PAS, showed that most cells contained more than one type of glycoprotein. In all regions, the cell content of sialylated glycoproteins increased, and of sulphated glycoproteins decreased during adaptation to sea water. The histochemical properties of the cuticle-secreting cells in the epidermis were less easy to study, but it seems that their content of neutral glycoproteins increased and their content of acid glycoproteins decreased, during adaptation to sea water. Mucous cells were generally less common in seawater-adapted animals, though in the epidermis of fish kept in sea water for 21 days, there were as many as in the freshwater controls. Sulphated glycoproteins may be more effective than others in freshwater osmoregulation for they are highly charged and could attract cations strongly. They may also help to combat bacterial and fungal infections, and perhaps these are less likely when laboratory fish are transferred to sea water.     

Fine scale genetic population structure of the freshwater and Omono types of nine-spined stickleback Pungitius pungitius (L.) within the Omono River system, Japan

The fine scale geographic population structure of two types of nine-spined stickleback Pungitius pungitius (the widely distributed freshwater type and a local endemic, the Omono type) within the Omono River system, Japan, was investigated. A principal components analysis of allele frequencies and neighbour-joining tree for pair-wise F _ST values, based on 10 allozyme loci, revealed that the Omono type was comprised of four regional groups with relatively high genetic divergence. This grouping was also supported by hierarchical analysis of molecular variance (AMOVA) with a higher variance component among the regional groups, and by an exact test with significant genotypic differentiation for all sample pairs among the regional groups. Moreover, in the clustering of individuals using the Bayesian method, most of individuals in each regional group were assigned the corresponding cluster. On the other hand, there were less pronounced regional groups of the freshwater type, although AMOVA, exact test for genotypic differentiation and Bayesian analysis indicated genetic divergence between two sampling sites in lower reach of the Omono River and other sites. The results suggest that the Omono type represented an earlier colonization, with subsequent invasion of the freshwater type.     

Hybrid male sterility between the fresh- and brackish-water types of ninespine stickleback Pungitius pungitius (Pisces, Gasterosteidae)

Two ecologically distinct forms, fresh- and brackish-water types, of ninespine stickleback co-exist in several freshwater systems on the coast of eastern Hokkaido. Recent genetic analyses of 13 allozyme loci revealed genetic separation between the two types even though their spawning grounds were in close proximity. On the other hand, there is only a small difference in mitochondrial DNA (mtDNA) sequence between the two types suggesting that they diverged quite recently or that mtDNA introgression occurred between them. To test for postzygotic reproductive isolating mechanisms and hybrid mediated gene flow, we examined the viability and reproductive performance of reciprocal F1 hybrids. The hybrids grew to the adult size normally and both sexes expressed secondary sexual characters in the reciprocal crosses. The female hybrids were reciprocally fertile, while the male hybrids were reciprocally sterile. Histological and flow-cytometric analyses of the hybrid testis revealed that the sterility pattern was classified as 'gametic sterility,' with gonads of normal size but abnormal spermatogenesis. To our knowledge, the present finding is a novel example of one sex hybrid sterility in the stickleback family (Gasterosteidae).     

Observations on the occurrence of Diplostomum spathaceum and Schistocephalus sp. in ninespine sticklebacks (Pungitius pungitius) from the Belcher Islands, Northwest Territories, Canada

All 175 ninespine sticklebacks, Pungitius pungitius (Linné), collected from the Belcher Islands were parasitized by Diplostomum spathaceum (Rudolphi) and 43% by Schistocephalus sp. D. spathaceum metacercariae were mostly confined to a dorso-ventral band encircling the lens of the eye, and were concentrated in the anterio-dorsal sector of this band. The central area of the lens was thus relatively free of diplostomula, probably minimizing interference with the vision of the fish. The frequency distribution of D. spathaceum abundance in P. pungitius was closely approximated by a negative binomial, while that for Schistocephalus was best fitted by a Poisson. None of the fish condition factors examined appeared related to the intensity of the parasitic infections.     

Climate and Landscape Factors Associated with Buruli Ulcer Incidence in Victoria,Australia

Background

Buruli ulcer (BU), caused by Mycobacterium ulcerans (M. ulcerans), is a necrotizing skin disease found in more than 30 countries worldwide. BU incidence is highest in West Africa; however, cases have substantially increased in coastal regions of southern Australia over the past 30 years. Although the mode of transmission remains uncertain, the spatial pattern of BU emergence in recent years seems to suggest that there is an environmental niche for M. ulcerans and BU prevalence.

Methodology/Principal Findings

Network analysis was applied to BU cases in Victoria, Australia, from 1981–2008. Results revealed a non-random spatio-temporal pattern at the regional scale as well as a stable and efficient BU disease network, indicating that deterministic factors influence the occurrence of this disease. Monthly BU incidence reported by locality was analyzed with landscape and climate data using a multilevel Poisson regression approach. The results suggest the highest BU risk areas occur at low elevations with forested land cover, similar to previous studies of BU risk in West Africa. Additionally, climate conditions as far as 1.5 years in advance appear to impact disease incidence. Warmer and wetter conditions 18–19 months prior to case emergence, followed by a dry period approximately 5 months prior to case emergence seem to favor the occurrence of BU.

Conclusions/Significance

The BU network structure in Victoria, Australia, suggests external environmental factors favor M. ulcerans transmission and, therefore, BU incidence. A unique combination of environmental conditions, including land cover type, temperature and a wet-dry sequence, may produce habitat characteristics that support M. ulcerans transmission and BU prevalence. These findings imply that future BU research efforts on transmission mechanisms should focus on potential vectors/reservoirs found in those environmental niches. Further, this study is the first to quantitatively estimate environmental lag times associated with BU outbreaks, providing insights for future transmission investigations.     

Factors Controlling the Seasonal Variation of Nitrate in Lake Erken

The seasonal variation of the nitrate concentration in the mesotrophic Lake Erken is markedly regular and shows some important differences compared with that of phosphate. Nitrification occurs mainly at the sediment surface. Nitrate accumulates when the nitrification-denitrification sequence is broken at a time when the nitrate assimilation is small. This occurs in Lake Erken during autumn turnover.     

Comparison of taste preferences in the three-spined Gasterosteus aculeatus and nine-spined Pungitius pungitius sticklebacks from the White Sea Basin

Similarity between the taste preferences of classical taste substances and free L-amino acids in adult three-spined stickleback Gasterosteus aculeatus (forma leiurus) and nine-spined stickleback Pungitius pungitius (forma laevis) was found. The strongest and the most significant responses in both species were evoked by citric acid and cysteine, asparatic, and glutamic acids. Sodium chloride, calcium chloride, sucrose, and the remaining 18 amino acids do not elicit a statistically significant effect on the consumption of agar-agar pellets by the fish or have weak taste attractiveness. Similarity of taste preferences in the three-spined and nine-spined sticklebacks are supported by correlation analysis. Absolute values of the consumption of pellets of the same types are also similar in the two species. There were, however, differences in the behavioral taste response, repeated snaps, and the duration of processing of the pellets. The taste response of the nine-spined stickleback is more similar to taste responses in fish of the limnophilic complex than to the response in the three-spined stickleback. It is hypothesized that taste spectra may be very similar in fish with similar ecology and feeding patterns not only in sticklebacks, but also in other related species.     

The effect of suspended sediments on ninespine stickleback,Pungitius pungitius,and golden shiner,Notemigonus crysoleucas,in a current of varying velocity

Synopsis Ninespine stickleback, Pungitius pungitius, and golden shiner, Notemigonus crysoleucas, were exposed at 5 and 20°C to 0, 15, 75 and 150 JTU (Jackson Turbidity Units) of suspended sediments. Fish were tested in a trough inclined at 2.3° with an inflow rate of 27 ml sec^-1. Changes in swimming behaviour were only noted for golden shiner and at 20°C and 15, 75 and 150 JTU. Under these conditions golden shiners were more active, changing from location to location in the apparatus significantly more often at higher than at lower concentrations of suspended sediments. This behaviour is compatible with a fleeing response from a stress inducing agent.