Morphological differences in the skin of marble trout Salmo marmoratus and of brown trout Salmo trutta

Despite being genetically very closely related, the marble trout Salmo marmoratus and the brown trout Salmo trutta exhibit marked phenotypic differences, particularly with regard to skin pigmentation. Histological analysis of skin from the head and gill cover of differently aged individuals of the two species was carried out in order to characterize differences in skin structure. The basic structure of skin of the individuals studied corresponded with that described for other salmonids, though the head epidermis was somewhat thicker in S. marmoratus than in S. trutta, thickening with age in both species. Numerous secretory goblet cells and sporadic secretory sacciform cells were observed in the upper and middle part of the epidermis in both species. Melanophores were present in both species only in the dermis, and were bigger in S. marmoratus and present at lower average density than in S. trutta, and more or less constant across all age classes. In adult S. marmoratus with fully established marble pigmentation, light areas at low density with small (i.e. aggregated) melanophores were present, while in S. trutta melanophores were more uniformly distributed.     

Sympatric relationship between redband trout and non-native brook trout in the Southeastern Oregon Great Basin

Brook trout (Salvelinus fontinalis) and rainbow trout (Oncorhynchus mykiss) have been widely introduced outside their respective ranges within North America causing declines and displacement of native trout. Yet, successful coexistence of native and non-native trout has received little attention. Here we evaluated the effect of introduced brook trout on the size and density of native redband trout in two invaded sub-basins in southeastern Oregon. In a multi-year study, we investigated whether habitat and fish communities differed between streams and stream reaches where redband trout were allopatric versus where redband trout were sympatric with brook trout. We hypothesized that redband trout would be less dense and have smaller total length in sympatry with brook trout than in allopatry, but that total trout density would not differ. We investigated whether differences in habitat existed between sympatric and allopatric locations that would indicate differentiation in site level habitat preferences for each trout species. We found that sympatric locations had more wood but similar fish community structure. Mean length and densities of redband trout were higher at allopatric locations. However, in most years at sympatric locations total trout density was twice that of allopatric redband trout sites. Using comparable data from an eastern United States system where brook trout are native, sympatric sites had lower densities of brook trout; however, total trout density did not differ. We conclude that invading trout negatively impact native trout densities; but in southeastern Oregon system the negative impact is minimized.     

Season of birth and morningness: comparison between the northern and southern hemispheres

The present study explored the possible role of the photoperiod at birth on morningness by collecting data in the northern (Italy) and southern (Australia) hemispheres. To assess circadian typology, the Composite Scale of Morningness (CS) was administered to a sample of 1734 university students (977 Italian and 757 Australian; 1099 females and 635 males; age 24.79?±?7.45 yrs [mean?±?SD]). Consistent with the literature, females reported higher CS scores (morningness) than males, and Australian participants reported higher CS scores than Italian participants. Allowing for the fact the seasons are reversed between the hemispheres, the results are in line with previous studies. The authors found more evening types were born during the seasons associated with longer photoperiod (spring and summer), and more morning types were born during the seasons associated with shorter photoperiod (autumn and winter), indirectly supporting an imprinting-like phenomenon played by the photoperiod at birth.     

Evolutionary relationship between initial enzymes of tetrapyrrole biosynthesis

Glutamate-1-semialdehyde 2,1-aminomutase (GSAM) is the second enzyme in the C(5) pathway of tetrapyrrole biosynthesis found in most bacteria, in archaea and in plants. It catalyzes the transamination of glutamate-1-semialdehyde to 5-aminolevulinic acid (ALA) in a pyridoxal 5'-phosphate (PLP)-dependent manner. We present the crystal structure of GSAM from the thermophilic cyanobacterium Thermosynechococcus elongatus (GSAM(Tel)) in its PLP-bound form at 2.85A resolution. GSAM(Tel) is a symmetric homodimer, whereas GSAM from Synechococcus (GSAM(Syn)) has been described as asymmetric. The symmetry of GSAM(Tel) thus challenges the previously proposed negative cooperativity between monomers of this enzyme. Furthermore, GSAM(Tel) reveals an extensive flexible region at the interface of the proposed complex of GSAM with glutamyl-tRNA reductase (GluTR), the preceding enzyme in tetrapyrrole biosynthesis. Compared to GSAM(Syn), the monomers of GSAM(Tel) are rotated away from each other along the dimerization interface by 10 degrees . The associated flexibility of GSAM may be essential for complex formation with GluTR to occur. Unexpectedly, we find that GSAM is structurally related to 5-aminolevulinate synthase (ALAS), the ALA-producing enzyme in the Shemin pathway of alpha-proteobacteria and non-plant eukaryotes. This structural relationship applies also to the corresponding subfamilies of PLP-dependent enzymes. We thus propose that the CoA-subfamily (including ALAS) and the aminotransferase subfamily II (including GSAM) are evolutionarily closely related and that ALAS may thus have evolved from GSAM.     

Reproduction of Pelagia noctiluca in the central and northern Adriatic Sea

The sequence of vitellogenesis as related to size increase of the oocytes of Pelagia noctiluca (Forskål) (Scyphozoa, Semaeostomeae) was examined to assess the influence of climatic factors on its reproductive period in the central and northern Adriatic Sea. From 1981 to 1985, 5 specimens with similar diameter were sampled each month. One ovary was excised from each individual and examined both with a videoanalyzer, to count the oocytes and to check their size distribution, and through histology to assess the stage of maturation in relation to the diameter. Oocytes of all stages were present in the ovaries of individuals down to a bell diameter of 3.5 cm. Thus reproduction occurs throughout the year in the central and north Adriatic Sea. However, the number of oocytes in different developmental stages in a gonad may range from a minimum value recorded in summer to two peaks in spring and autumn. The quantitative distribution is related to sea temperature and thus to metabolic rate, and to food availability.     

Evolutionary relationship between human major histocompatibility complexHLA-DR haplotypes

 HLA-DR haplotypes of the human major histocompatibility complex are organized in five different groups. They can be identified based on the serological specificity expressed by the polymorphic DRB1 locus and by the presence of a characteristic set of DRB genes. The nucleotide sequences of introns 4 and 5 of the two DRB genes (DRB1 ^* 01 and DRB6 ^* 01) from a DR1 haplotype and the three DRB genes (DRB1 ^* 15, DRB6 ^* 15, and DRB5 ^* 15), from a DR51 haplotype were determined. This study identified endogenous retroviral long terminal repeat elements (ERV9 LTR) located at identical positions in intron 5 of the DRB1 genes in both the DR1 and DR51 haplotypes. Phylogenetic analyses revealed a close evolutionary relationship between these two haplotypes. The DRB5 gene, unique for the DR51 haplotype, may have been lost by a recent gene deletion event creating the DR1 haplotype. A model for the evolution of the human DR haplotypes involving separate duplication and contraction events is presented. Received: 10 October 1995 / Revised: 22 November 1995     

The benthic foraminiferal communities of the northern Adriatic continental shelf

Off the Po Delta in the northern Adriatic, three different foraminiferal associations were identified in the fraction >0.125 mm of 25 sediment samples. The first association concerns sample stations between depths of 5 and 13.5 m in the shallow, nutrient-rich belt and is characterised by dominant Ammonia beccarii. The second occupies the 29.5–38.5-m-deep, nutrient-rich zone of clay-rich sediment, where inputs from the Po are concentrated, and is dominated by Nonionella opima. The third association, in the 21–46-m-deep and nutrient-poor zone, is dominated by Textularia agglutinans. The same distribution of communities was obtained using total associations (living and dead specimens) and biocenosis (stained individuals). The good correspondence with the foraminiferal distributions described in the past indicates that, in spite of the occurrence of anoxic and dysoxic events, the environmental state in the northern Adriatic may be considered stable.     

Genetic introgression between wild and stocked brown trout in the Douro River basin, Spain

The genetic diversity of Spanish brown trout is currently threatened by stocking with exogenous brown trout from Central and Northern Europe. In the Douro River basin 25% of the analysed populations in the present study showed introgression by genes of hatchery origin. The mean introgression estimated by the single locus approach ( S ) varied from 0 to 22% among populations, with a mean value of 3%. The hatchery allele markers were absent in populations where stocking ceased in 1993. However, the introgression effect was observed in all populations stocked until 1998. It seems that cessation of stocking is a good measure for restoring native populations. A thorough review of published and present data of genetic interactions between wild and stocked brown trout in Spanish rivers indicates different levels of introgression between basins. The absence of a clear geographical pattern in the introgression level suggests that ecological interactions and local stocking programmes may play an important role in stocking success. Finally, several guidelines are provided for conservation and management of native brown trout populations in Spanish rivers.     

Boundary zone between northern and southern pig-tailed macaques and their morphological differences

Based on previous conflicting reports that the two forms of pig-tailed macaque (northern and southern) exist as separate species, subspecies, or forms, and that their boundary zone lies in Thailand, a survey of the distribution range and morphology of pig-tailed macaques in Thailand was conducted during 2003–2010. We first conducted a questionnaire survey. Questionnaires were sent to 7,410 subdistricts throughout Thailand. We then traveled to 72 of the 123 subdistricts reporting the presence of pig-tailed macaques. However, due to a lack of reports of the presence of free-ranging pig-tailed macaques living south of the Isthmus of Kra, a survey of pet pig-tailed macaques was also conducted during 16–24 September 2011. Furthermore, 35 wild northern pig-tailed macaques inhabiting northern Thailand (13°13′N, 101°03′E) were temporarily caught and their morphological characters were measured and then compared to those of the southern form captured from Sumatra, Indonesia. Although largely allopatric, the ranges of the northern and southern pig-tailed macaques in Thailand were found to have a partially sympatric boundary at the Surat Thani–Krabi depression (8–9°30′N). Morphologically, these two forms were very distinctive, with different morphological characters such as the crown patch, the white color of the triangle above the eyes, the red streak at the external rim of the eyes, pelage color, ischial callosity, tail length and carriage, facial height, and limb length in both sexes, and patterns of sex skin swelling and reddening in females. These differences in morphological characters between the northern and southern forms should help settle the problems of their taxonomy.     

The effect of recurrent floods on genetic composition of marble trout populations

A changing global climate can threaten the diversity of species and ecosystems. We explore the consequences of catastrophic disturbances in determining the evolutionary and demographic histories of secluded marble trout populations in Slovenian streams subjected to weather extremes, in particular recurrent flash floods and debris flows causing massive mortalities. Using microsatellite data, a pattern of extreme genetic differentiation was found among populations (global F(ST) of 0.716), which exceeds the highest values reported in freshwater fish. All locations showed low levels of genetic diversity as evidenced by low heterozygosities and a mean of only 2 alleles per locus, with few or no rare alleles. Many loci showed a discontinuous allele distribution, with missing alleles across the allele size range, suggestive of a population contraction. Accordingly, bottleneck episodes were inferred for all samples with a reduction in population size of 3-4 orders of magnitude. The reduced level of genetic diversity observed in all populations implies a strong impact of genetic drift, and suggests that along with limited gene flow, genetic differentiation might have been exacerbated by recurrent mortalities likely caused by flash flood and debris flows. Due to its low evolutionary potential the species might fail to cope with an intensification and altered frequency of flash flood events predicted to occur with climate change.     

The evolution and phytoplankton composition of mucilaginous aggregates in the northern Adriatic Sea

Recurrent occurrences of visible mucilage “clouds” that cover areas up to several hundred kilometres with vertical dimensions of 20–30 m have been recorded in the stratified water column in the northern Adriatic. In the past this was described as “mare sporco” phenomenon. Past studies of the phenomenon indicated that phytoplankton is an important component of mucilage. Our research revealed the composition of phytoplankton assemblages in different types of mucilaginous aggregates collected during the summers of 1997 and 2000 using pigment biomarkers (HPLC). Phytoplankton biomass in the mucilage samples was very high, ranging from 7.9 μg g⁻¹ to 390.8 μg g⁻¹ of chlorophyll a per unit of dry mass of mucilage. The phytoplankton community in the early, loose stage of mucilaginous aggregates was heterogeneous, as indicated by the diversity of detected pigments. The number of phytoplankton groups decreased as the aggregates aged and diatoms increased in relative biomass (up to 92.7%). Phytoplankton biomass in seawater was similar in years with and without mucilage; however, significantly higher contributions to the total biomass of 19′-hexanoyloxyfucoxanthin-containing phytoplankton (prymnesiophytes) were found in the upper 10 m in spring of the “mucilaginous years” (1997 and 2000) followed by prevalence of diatoms in summer. The F_p pigment index used to assess seawater trophic conditions reached lower values in April–May in mucilaginous years (1997 and 2000) compared to non-mucilaginous years (1998 and 1999). We conclude that the role of prymnesiophytes and other small flagellates is crucial for the initial phases of mucilage appearance. Aggregates represent a favourable environment for the secondary development of opportunistic diatoms that foster mucilage formation.     

Long-term changes in community composition and life-history traits in a highly exploited basin (northern Adriatic Sea): the role of environment and anthropogenic pressures

The changes in a marine community in the northern Adriatic Sea were explored over a period of 65 years using landings data from a commercial fishing fleet, and the role of fishing pressure and environmental variations in driving these changes was investigated. A total of 40 taxonomic categories, including one or several species, were analysed, representing 93·7% of the total landings. From 1945 to 2010 a significant decrease in the evenness index was observed, indicating a trend towards landings dominated by fewer taxa. The composition of the landings showed a temporal shift during the 1980s; from 1945 to the 1980s a continuous, clear change in composition took place, probably driven by an increase in fishing pressure as well as riverine nutrient inputs. Since the 1980s, a different trend of changing composition emerged. Among the analysed predictors, fishing capacity, summer seawater temperature, inflow from the Po River (the major river of the northern Adriatic Sea) and nutrients were related to the changes in landings. In relation to life-history traits of the landed species, the community shifted from large, late-maturing species to more fecund, smaller and earlier-maturing species. A high fishing pressure is probably the major cause of these changes, possibly acting synergistically with environmental variations.     

On the origin of northern and southern hemisphere grasslands

The origin of the grassy habit during the Eocene and the development of C4 grasses during the Miocene/Pliocene boundary are discussed before the origin of primary and secondary grassland in Eurasia and North America are discussed. A comparison shows that both Northern and Southern hemisphere primary grassland originated due to climatic changes to drier conditions during the end of the Eocene, and that modern grassland vegetation types can be traced back to the Oligocene. The Eurasian steppes becomes more fragmented towards the west and south and relicts of primary grassland exists only in the most xerothermic localised habitats in central and western Europe. Secondary grassland clearly due to manmade deforestation, started with the spread of Neolithic husbandry. Southern African grasslands were however not only determined by droughty conditions, but cooler conditions at high altitudes are one of the major driving forces that prevent colonisation by trees of a generally tropical origin.     

Oocyte development in four species of scyphomedusa in the northern Adriatic Sea

Oocyte development was followed in 4 species of Scyphomedusae. In Pelagia noctiluca a centrifugal maturity gradient is present. Vitellogenesis may be related first to exogenous endodermal production and later to oocyte endogenous activity. Simultaneously, the paraovular body (POB) develops from the secondary endoderm; it is connected to the oocyte and controls secretion of mucus, which envelops the oocyte during spawning. In Aurelia aurita, there is no maturity gradient, nor any differentiated structures of endodermal origin, associated with oocytes. In Discomedusa lobata a maturity gradient is absent. Its vitellogenesis is similar to that in P. noctiluca, and is associated with structural modification of the secondary endoderm in the area contacting the oocyte. This structure is cytologically similar to the POB of P. noctiluca, though less differentiated. Spawning is similar to that of P. noctiluca, with fenestration of the surrounding endodermal cells as the oocyte passes from the ovary to the genital sinus. In Rhizostoma pulmo a maturity gradient is absent. An early and fairly evident development of the vitelline membrane was observed.     

Sarcinomyces petricola, a new microcolonial fungus from marble in the Mediterranean basin

A new meristematic black yeast species, Sarcinomyces petricola, is described. All strains known to date were isolated from sun-exposed marble in the Mediterranean basin. On the basis of PCR-ribotyping and nutritional physiology, the species is classified as an anamorph member of the ascomycete family Herpotrichiellaceae (Chaetothyriales).     

Gene pool differences between northern and southern Altaians inferred from the data on Y-chromosomal haplogroups

Y-chromosomal haplogroups composition and frequencies were analyzed in Northern and Southern Altaians. In the gene pool of Altaians a total of 18 Y-chromosomal haplogroups were identified, including C3xM77, C3c, DxM15, E, F*, J2, I1a, I1b, K*, N*, N2, N3a, O3, P*, Q*, R1*, R1a1, and R1b3. The structured nature of the Altaic gene pool is determined by the presence of the Caucasoid and Mongoloid components, along with the ancient genetic substratum, marked by the corresponding Western and Eastern Eurasian haplogroups. Haplogroup R1a1 prevailed in both ethnic groups, accounting for about 53 and 38% of paternal lineages in Southern and Northern Altaians, respectively. This haplogroup is thought to be associated with the eastward expansion of early Indo-Europeans, and marks Caucasoid element in the gene pools of South Siberian populations. Similarly to haplogroup K*, the second frequent haplogroup Q* represents paleo-Asiatic marker, probably associated with the Ket and Samoyedic contributions to the Altaic gene pool. The presence of lineages N2 and N3a can be explained as the contribution of Finno--Ugric tribes, assimilated by ancient Turks. The presence of haplogroups C3xM77, C3c, N*, and 03 reflects the contribution of Central Asian Mongoloid groups. These haplogroups, probably, mark the latest movements of Mongolian migrants from the territory of contemporary Tuva and Mongolia. The data of factor analysis, variance analysis, cluster analysis, and phylogenetic analysis point to substantial genetic differentiation of Northern and Southern Altaians. The differences between Northern and Southern Altaians in the haplogroup composition, as well as in the internal haplotype structure were demonstrated.     

Evolutionary ecology of the relationship between oviposition preference and performance of offspring in phytophagous insects

The relationship between oviposition preference and growth, survival, and reproduction of offspring is the crux of the problem in the evolution of host associations between phytophagous insects and plants. Observed relationships between oviposition preference and performance of offspring range from good to poor. At least four hypotheses have been suggested to explain observed use of particular host plants that may not result in the fastest growth rates or greatest pupal masses: time, patch dynamics, parasite versus grazer lifestyles, and enemy-free space. Our current understanding of these relationships, however, is hampered by an almost complete lack of data on how preference and performance are related genetically. These data are needed to understand the origins of covariance between preference and performance and constraints on the evolution of host associations.