A phyletic study on lacustrine haplochromine fishes (Perciformes, Cichlidae) of East Africa, based on scale and squamation characters

Phyletic relations within the haplochromine cichlids of East Africa were investigated using scale and squamation characters. Within the L. Victoria–Edward–Kivu species flock most of the genera proposed in Greenwood's revision could be confirmed by this approach. In addition the genera could be interrelated phylogenetically. They form two distinct superlineages comprising several genera each. The genus Astatotilapia as conceived by Greenwood is diphyletic. The fluviatile members of the genus form the sister taxon of the L. Victoria–Edward–Kivu flock, while the rest are a subgroup of that flock. The flock seems to be of monophyletic origin.     

The status of the West African fish Gobius nigricinctus with reference to New World autochthones and an Old World colour-analogue

The systematic features of a small West African marine gobiid fish, Gobius nigricinctus Delais 1951, are redescribed from the holotype with special emphasis on the head lateral-line canal and sensory papillae (tree neuromast) systems. A junior synonym is found to be Gobius lepidogenys Robins 1970. The status of G. nigricinctus is best expressed in a new monotypic genus, Gorogobius , with closest affinity to the Atlantic-Mediterranean Corcyrogobius and Odondebuenia , Similarities in head sensory papillae arrangement exist between Gorogobius and certain 'seven-spined' genera of the New World tropical insular fauna, but G. nigricinctus is shown not to be a recent transatlantic immigrant. The validity of the tribe Gobiosomini as a natural grouping endemic to the Americas is questioned. Close resemblance in striped coloration between Gorogobius and small Indo-West Pacific gobies, especially Quisquilius eugenius , is shown to be the result of convergent evolution.     

Immunological cross-reactions among gadidae parvalbumins

Antisera raised against apparently homogeneous whiting parvalbumin III have been found to recognize two non cross-reacting molecular species of parvalbumins. Aliquots of these antisera have been separately absorbed with two distinct parvalbumins from a near-related fish species, namely haddock parvalbumins II and III, and also with the homologous antigen. The immunochemical reactivities of absorbed and non-absorbed antisera toward parvalbumins from nine Gadidae species have been systematically explored by immunoelectrophoresis. The observed cross-reactions lead to distinguish two groups among Gadidae parvalbumins. So far this discrimination can be correlated with differences in amino-acid compositions, peptide maps and sequences which are known to characterize several protein members from each of the two groups. Using the same anti-whiting antisera, a tenuous common antigenic reactivity is shown between Gadidae and some Cyprinidae parvalbumins.     

Molecular ecophysiology of Antarctic notothenioid fishes

The notothenioid fishes of the Southern Ocean surrounding Antarctica are remarkable examples of organismal adaptation to extreme cold. Their evolution since the mid-Miocene in geographical isolation and a chronically cold marine environment has resulted in extreme stenothermality of the extant species. Given the unique thermal history of the notothenioids, one may ask what traits have been gained, and conversely, what characters have been lost through change in the information content of their genomes. Two dramatic changes that epitomize such evolutionary transformations are the gain of novel antifreeze proteins, which are obligatory for survival in icy seawater, by most notothenioids and the paradoxical loss of respiratory haemoproteins and red blood cells, normally deemed indispensable for vertebrate life, by the species of a highly derived notothenioid family, the icefishes. Here, we review recent advances in our understanding of these traits and their evolution and suggest future avenues of investigation.The formerly coherent paradigm of notothenioid freeze avoidance, developed from three decades of study of antifreeze glycoprotein (AFGP) based cold adaptation, now faces challenges stemming from the recent discovery of antifreeze-deficient, yet freeze-resistant, early notothenioid life stages and from definitive evidence that the liver is not the physiological source of AFGPs in notothenioid blood. The resolution of these intriguing observations is likely to reveal new physiological traits that are unique to the notothenioids. Similarly, the model of AFGP gene evolution from a notothenioid pancreatic trypsinogen-like gene precursor is being expanded and refined based on genome-level analyses of the linked AFGP loci and their ancestral precursors. Finally, the application of comparative genomics to study evolutionary change in the AFGP genotypes of cool-temperate notothenioids from sub-Antarctic habitats, where these genes are not necessary, will contribute to the mechanistic understanding of the dynamics of AFGP gene gain and loss.In humans and most vertebrates, mutations in the alpha- or beta-globin genes or defects in globin chain synthesis are causes of severe genetic disease. Thus, the 16 species of haemoglobinless, erythrocyte-null icefishes are surprising anomalies -- in fact, they could only have evolved and thrived due to relaxed selection pressure for oxygen-binding proteins in the cold, oxygen-rich waters of the Southern Ocean. Fifteen of the sixteen icefish species have lost most of the adult alphabeta-globin locus and retain only a small 3' fragment of the alpha-globin gene. The only exception to this pattern occurs in Neopagetopsis ionah, which possesses a disrupted alphabeta-globin gene complex that probably represents a non-functional intermediate on the evolutionary pathway to near total globin gene extinction. By contrast, six of the icefish species fail to express myoglobin. The absence of myoglobin expression has occurred by several independent mutations and distinct mechanisms. Haemoprotein loss is correlated with dramatic increases in cellular mitochondrial density, heart size, blood volume and capillary bed volume. Evolution of these compensatory traits was probably facilitated by the homeostatic activity of nitric oxide, a key modulator of angiogenesis and mitochondrial biogenesis. These natural knockouts of the red blood cell lineage are an excellent genomic resource for erythroid gene discovery by comparative genomics, as illustrated for the newly described gene, bloodthirsty.     

Female throat ornamentation does not reflect cell-mediated immune response in bluethroats Luscinia s. svecica

The brilliantly coloured throat patch in male bluethroats, Luscinia s. svecica, influences their social mating success and both within- and extra-pair paternity. Female bluethroats are highly variable in their extent of throat coloration, from entirely drab to almost male-like. The ornament in females could be due to a genetic correlation between the sexes. However, it has been shown that male bluethroats prefer brightly coloured females, suggesting that female ornamentation has evolved by direct sexual selection on females through male choice. Males may prefer extravagant traits in females if these reliably signal female quality, such as resistance to disease. We investigated whether variation in the extent of structural and melanin plumage ornamentation in female bluethroats reflects cell-mediated immune response. We caught the females at their nests and measured their immune response as a swelling following a challenge by phytohemagglutinin. An analysis of the data from two years of study revealed that the cell-mediated immune response was not related to female ornamentation. However, the immune response was strongly correlated with female body condition. Thus, our results do not support the hypothesis that female ornament expression signals quality in terms of cell-mediated immunity.     

眼皮肤白化病分型及珊基因新突变的鉴定

目的了解我国眼皮肤白化病（oculocutaneous albinism,OCA）的分型和相关基因突变类型,探讨新突变可能的分子致病机制。方法应用PCR方法扩增TYR基因,经DNA序列测定检出突变,采用错配引物PCR进行新突变的群体筛查,结合生物信息学方法探讨一种新突变的致病性和可能的分子致病机制。结果10名患者中有5人存在2个突变TYR等位基因,共计8种突变类型,其中c．71G〉A（C24Y）和c．841G〉T（E281X）是OCA1A致病性新突变;C24极可能参与二硫键形成,C24Y将导致酪氨酸酶肽链内此二硫键消失,进而引起蛋白空间构象变化和功能异常而致病。结论从基因水平初步了解了我国OCA1所占的比例,探讨了TYR基因C24Y的致病性并初步阐明了其致病的分子机制。本结果丰富了人类TYR基因突变类型,为我国OCA分型诊断、产前基因诊断和遗传咨询等积累了有价值的数据资料。     

Coincident disruptive coloration

Even if an animal matches its surroundings perfectly in colour and texture, any mismatch between the spatial phase of its pattern and that of the background, or shadow created by its three-dimensional relief, is potentially revealing. Nevertheless, for camouflage to be fully broken, the shape must be recognizable. Disruptive coloration acts against object recognition by the use of high-contrast internal colour boundaries to break up shape and form. As well as the general outline, characteristic features such as eyes and limbs must also be concealed; this can be achieved by having the colour patterns on different, but adjacent, body parts aligned to match each other (i.e. in phase). Such 'coincident disruptive coloration' ensures that there is no phase disjunction where body parts meet, and causes different sections of the body to blend perceptually. We tested this theory using field experiments with predation by wild birds on artificial moth-like targets, whose wings and (edible pastry) bodies had colour patterns that were variously coincident or not. We also carried out an experiment with humans searching for analogous targets on a computer screen. Both experiments show that coincident disruptive coloration is an effective mechanism for concealing an otherwise revealing body form.     

Albinism in the domestic cat (Felis catus) is associated with a tyrosinase (TYR) mutation

Albino phenotypes are documented in a variety of species including the domestic cat. As albino phenotypes in other species are associated with tyrosinase (TYR) mutations, TYR was proposed as a candidate gene for albinism in cats. An Oriental and Colourpoint Shorthair cat pedigree segregating for albinism was analysed for association with TYR by linkage and sequence analyses. Microsatellite FCA931, which is closely linked to TYR and TYR sequence variants were tested for segregation with the albinism phenotype. Sequence analysis of genomic DNA from wild-type and albino cats identified a cytosine deletion in TYR at position 975 in exon 2, which causes a frame shift resulting in a premature stop codon nine residues downstream from the mutation. The deletion mutation in TYR and an allele of FCA931 segregated concordantly with the albino phenotype. Taken together, our results suggest that the TYR gene corresponds to the colour locus in cats and its alleles, from dominant to recessive, are as follows: C (full colour) > c(b) (burmese) > or = c(s) (siamese) > c (albino).     

Morphological evaluation of spermatogenesis in Lake Magadi tilapia (Alcolapia grahami): A fish living on the edge

Spermatogenesis in Lake Magadi tilapia (Alcolapia grahami), a cichlid fish endemic to the highly alkaline and saline Lake Magadi in Kenya, was evaluated using light and transmission electron microscopy. Spermatogenesis, typified by its three major phases (spermatocytogenesis, meiosis and spermiogenesis), was demonstrated by the presence of maturational spermatogenic cells namely spermatogonia, spermatocytes, spermatids and spermatozoa. Primary spermatogonia, the largest of all the germ cells, underwent a series of mitotic divisions producing primary spermatocytes, which then entered two consecutive meiotic divisions to produce secondary spermatocytes and spermatids. Spermatids, in turn, passed through three structurally distinct developmental stages typical of type-I spermiogenesis to yield typical primitive anacrosomal spermatozoa of the externally fertilizing type (aquasperm). The spermatozoon of this fish exhibited a spheroidal head with the nucleus containing highly electron-dense chromatin globules, a midpiece containing ten ovoid mitochondria arranged in two rows and a flagellum formed by the typical 9 + 2 microtubule axoneme. In addition, the midpiece, with no cytoplasmic sheath, appeared to end blindly distally in a lobe-like pattern around the flagellum; a feature that was unique and considered adaptive for the spermatozoon of this species to the harsh external environment. These observations show that the testis of A. grahami often undergoes active spermatogenesis despite the harsh environmental conditions to which it is exposed on a daily basis within the lake. Further, the spermiogenic features and spermatozoal ultrastructure appear to be characteristic of Cichlidae and, therefore, may be of phylogenetic significance.