Helminth assemblages of the turtle Emydura macquarii (Pleurodira: Chelidae) Queensland, Australia

The helminth fauna of 76 Emydura macquarii from 3 river systems in central and northern Queensland was examined. Eleven species were found, including 2 nematodes, 6 trematodes, 1 aspidogastrean, 1 cestode, and 1 monogenean. Analysis of helminth diversity showed that the Fitzroy and Ross River turtles had communities of comparable diversity, but the helminth communities in Proserpine River turtles were much less diverse. The helminth communities in all localities were dominated by trematodes. Polystomoides australiensis was the most prevalent, being found in 60% of the Ross River turtles, 57% of the Fitzroy River turtles, and 46% of the Proserpine River turtles. Notopronocephalus peekayi was the most abundant species, with mean abundances of 5.9 in the Ross River turtles and 9.8 in the Fitzroy River turtles. Species richness, Simpson's Reciprocal Index, was highest, 4.68, for the Ross River helminth community, Sorensen's Qualitative Index showed 95% similarity between the Ross River and Fitzroy River communities, although Sorensen's Quantitative Index indicated only 35% similarity between the 2 sites. Host feeding patterns are likely the most important factor affecting species richness of the helminth infracommunities, as the majority of helminth species are transmitted by food-web interactions involving intermediate hosts.     

A phylogeny for side-necked turtles (Chelonia: Pleurodira) based on mitochondrial and nuclear gene sequence variation

Aspects of the phylogeny of pleurodiran turtles are contentious, particularly within the Chelidae. Morphological analyses group the long-necked Australasian Chelodina and the long-necked South American Chelus and Hydromedusa into a single clade, suggesting a common derived origin of the long neck and associated habits that predated the separation of Australia from South America. In contrast, published analyses of 12SrRNA and cytochrome b sequences suggest that the long-necked Chelodina are more closely related to the short-necked Australasian genera than to either Chelus or Hydromedusa. This paper adds partial sequences of 16S rRNA and CO1 mitochondrial genes and partial sequences of the nuclear oncogene c-mos to test a range of previous hypotheses on the phylogenetic relationships among chelid turtles. In total, 1382 nucleotides were available for each of 25 taxa after elimination of ambiguously aligned regions. These taxa included representatives of all the genera of the turtle families Chelidae and Pelomedusidae, the three sub-genera of Phrynops, and recognized sub-generic groups of Elseya and Chelodina. Of the four genes examined, 12S rRNA was the most informative, followed by c-mos with 16S rRNA and CO1 the least informative. The molecular data support the currently accepted arrangement for pelomedusid genera, that is, a sister relationship between the African Pelusios and Pelomedusa and a clade comprising the South American Peltoceplhalus and Podocnemis with the Madagascan Erymnochelys. However, there is also support for Erymnochelys and Podocnemis as sister taxa to the exclusion of Peltocephalus (bootstrap values of 69–80%) which is at odds with the most commonly accepted arrangement. The South American chelids are monophyletic (76–82%). This clade includes the long-necked Chelus and Hydromedusa, but excludes the Australasian long-necked Chelodina. Furthermore, the South American long-necked chelids are not themselves monophyletic, with 98–100% bootstrap values for the node supporting Chelus and the remaining South American chelids to the exclusion of Hydromedusa. Hence, the hypothesis of a monophyletic grouping of the long-necked genera of South America and Australasia is not supported by the molecular data. Although reciprocal monophyly of the South American and Australasian chelid faunas was the most likely and the most parsimonious arrangement in all but one analysis, bootstrap support for the monophyly of the Australasian chelids was low (52–66%). The South American chelids, Chelodina and the short-necked Australasian chelids form an unresolved trichotomy. The genera Phrynops and Elseya are paraphyletic, leading to a recommendation to elevate the three sub-genera of Phrynops to generic status and support for previous suggestions to erect a new genus for Elseya latistermum and close relatives. A revised classification of the extant Pleurodira is presented, consistent with the phylogenetic relationships that emerge from this study.     

The primary structure of myoglobin from pacific green sea turtle (Chelonia mydas caranigra)

The amino acid sequence of the main component myoglobin from skeletal muscle of Pacific green sea turtle (Chelonia mydas caranigra) has been determined. The globin is 153 residues in length and has a free amino-terminus. The heme-binding and internal residues are as found in mammalian myoglobins. Ten substitutions are observed between this myoglobin and that from map turtle. About 38, 52, 47 and 86 substitutions are noted in comparison with the myoglobins of other reptiles, mammals, birds and fish, respectively. The inferred pattern of structural stabilization and conservation of two loci are typical of tetrapod myoglobin.     

Morphology and function of the feeding apparatus of Pelusios castaneus (Chelonia; Pleurodira)

Feeding mechanics of vertebrates depend on physical constraints of the surrounding media, water or air. Such functions are inseparably combined with form. The aim of this study is to show this linkage for the pleurodiran freshwater turtle Pelusios castaneus and, additionally, to point out the major functional and biomechanical distinctions between aquatic and terrestrial feeding turtles as well as several intermediate forms. Gross morphological investigations of skull, hyoid, tongue, and connected musculature, as well as scanning electron microscopy of the tongue surface, show typical features of an aquatic feeder, e.g., strongly developed hyoid apparatus vs. a small tongue with only moderate papillae, and massive jaw and hyoid musculature. Additionally, the special function of the esophagus during feeding is investigated to elucidate the problems of a bidirectional feeder. The esophagus is highly distensible in order to store the excess water sucked in during feeding until the prey is fixed by the jaws. The distension is probably achieved by a coincidence of active (branchial horn) as well as passive (water) components. P. castaneus is a feeding generalist, and is well adapted to the aquatic medium in terms of its functional as well as morphological features.     

Nematode parasites of the turtle Pelusios sinuatus (pelomedusidae: Pleurodira) from southern Africa

Summary Two nematode parasites are described from the turtle Pelusios sinuatus of southern Africa. Camallanus chelonius n. sp. (Camallanoidae) is easily distinguished from other species reported from Africa in possessing less than 10 smooth ridges in the buccal valves. It most closely resembles a group of seven species described from Indian amphibians but may be differentiated from these by a combination of characters: shape of the female tail and distal end of the spicules, male caudal papillae, presence or absence of small barbs between the bases of the buccal valve ridges. C. chelonius is intermediate in cephalic morphology between other Camallanus spp., which are all restricted to fish and amphibian hosts, and the genus Serpinema reported only in turtles. Falcaustra pelusios n.sp. (Cosmocercoidea) is the first species of the genus reported in pelomedusid turtles. It is easily distinguished from all other species by the presence of two large and complex cheilostomal rings in the cephalic end, a very short male tail, large gubernaculum, relatively short thick spicules and large number (more than 50 pairs) of subventral preanal muscle cells posterior to the sucker. ac]19810907     

Reproduction of the Australian freshwater turtle Emydura krefftii (Chelonia: Chelidae)

A study of the reproduction of Krefft's river tortoise, Emydura krefftii , was conducted in the perched dune lakes of Fraser Island, Queensland. Mature male specimens exhibit a postnuptial pattern of spermatogenesis typical of temperate-zone turtles elsewhere, with a peak in spermatogenic activity in autumn and a cessation of activity during the breeding season in spring and early summer. The spermatogenic cycle is paralleled by seasonal variation in testicular weight (standardized for body size) and in the diameter of the seminiferous tubules. Sperm are abundant in the epididymal canals throughout the year. Mating was observed in autumn, late winter and spring.
Females have a cyclic reproductive pattern, with distinct phases of follicular enlargement, ovulation and oviducal period, and quiescence. Yolk begins to accumulate in the ovaries in late summer, and the accumulation continues unabated through the winter, presumably by the transfer of material from fat stores to the ovaries. Ovulations occur from late winter to mid-summer. Atresia of follicles that fail to ovulate was demonstrated histologically.
Emydura krefftii lay up to three clutches of hard-shelled ellipsoid eggs per season. Each clutch contains between four and 10 eggs; the number is strongly correlated with maternal body size. Reproductive potential ranges from 12 eggs per annum for a female that has recently matured (carapace length c. 150 mm), to 30 eggs per annum for a full-sized female (length c. 250 mm). Selected life-history traits of Emydura krefftii are discussed in the context of findings for other populations of the species and for other species of freshwater turtle.     

The Green sea turtle (Chelonia mydas): mating, nesting and hatching on a farm

The collection of eggs from wild rookeries for incubation and hatching on the Mariculture Ltd farm on Grand Cayman Island, BWI, was described in the previous paper. It was realized, however, that this method of stocking the farm must sooner or later be superseded by the production of farm-laid eggs, and at an early stage a start was made on the task of establishing a breeding colony. The necessary collection of adult turtles and progress in breeding to the end of 1973 is described in the present paper.     

Oviducal development in a Krefft's river turtle,Emydura krefftii gray (Chelonia: Chelidae)

A clutch of Emydura krefftii eggs hatched 20 days after oviposition, in contrast to the normal incubation period of 45–50 days for this species. This shortened incubation and the presence of stage 20–21 embryos at oviposition indicates facultative oviducal development in E krefftii.     

The primary structures of gundi (Ctenodactylus gundi, Rodentia) hemoglobin and myoglobin

The primary structures of the alpha- and beta-chains of hemoglobin and myoglobin from the gundi (Ctenodactylus gundi, Rodentia) are presented. The sequences were determined after enzymatic and chemical cleavages of the polypeptide chains and by sequencing of the peptides mainly by automated sequence analysis. The sequences of gundi hemoglobin chains and of myoglobin are compared with those of other rodents.     

Characterization of polymorphic microsatellite markers for the green turtle (Chelonia mydas)

We describe primers and polymerase chain reaction conditions to amplify 12 microsatellite loci from the green turtle (Chelonia mydas), including one dinucleotide, four trinucleotide and seven tetranucleotide loci. The primers were tested on 78 individuals from a Pacific population nesting in the Hawaiian Islands. The primer pairs developed in this study yielded an average of 8.33 alleles per locus (range of 3-15 alleles), an average observed heterozygosity of 0.668 (range 0.309-0.910), and an average polymorphic information content of 0.647 (range 0.287-0.894).     

The Green sea turtle (Chelonia mydas): further observations on breeding in captivity

Mating, nesting and hatching of the Green sea turtle on Mariculture Ltd's farm on Grand Cayman Island, BWI in 1973 were recorded in a previous paper. The results described were the first of their kind, so that events in the farm breeding colony in the following year were awaited with much interest, especially as to hatchability of the eggs. The observations made in 1974, which extended and mainly confirmed those made in 1973, are described below.     

The Green sea turtle (Chelonia mydas): nesting on Ascension Island, 1973–1974

The collection of eggs of Chelonia mydas from beaches on Ascension Island and elsewhere for hatching at the Mariculture Ltd farm on Grand Cayman was described in a previous paper (Simon, 1975). Improved organization of these collections has made it possible to record many incidental observations which throw light on the nesting behaviour and performance of the female Chelonia , and Ascension Island, because of its small size, numerous beaches and good communications, proved to be particularly favourable for such research. The present paper records observations made in February and March 1973 and 1974. The second author has contributed only by the analysis of the data and the preparation of the paper.     

Two new species of Choanocotyle Jue Sue and Platt, 1998 (Digenea: Choanocotylidae) from an Australian freshwater turtle (Testudines: Pleurodira: Chelidae)

Choanocotyle hobbsi n. sp. and Choanocotyle juesuei n. sp. are described from the small intestine of the oblong turtle Chelodina oblonga from the vicinity of Perth, Western Australia. These are the third and fourth species referred to Choanocotyle. Choanocotyle hobbsi is most similar to Choanocotyle nematoides but differs in the size and shape of the oral sucker and the absence of a median loop in the cirrus sac. Choanocotyle juesuei is most similar to Choanocotyle elegans but differs in the size of the oral sucker and other morphometric criteria. Comparative analysis of the sequences of different nuclear ribosomal deoxyribonucleic acid regions of C. nematoides and C. hobbsi has confirmed that they are closely related but distinct species.     

Conformational changes of alpha-macroglobulin and ovomacroglobulin from the green turtle (Chelonia mydas japonica)

Green turtle plasma alpha-macroglobulin and ovomacroglobulin underwent conformational changes when they were treated with proteinases or methylamine. Their conformational changes were studied by HPLC gel chromatography, circular dichroism, and electron microscopy. The Stokes radii of native green turtle alpha-macroglobulin and ovomacroglobulin were estimated to be 84.3 +/- 0.5 A, and 93.0 +/- 0.5 A, respectively, by means of an HPLC experiment. After reaction with methylamine or proteinases, the Stokes radius of alpha-macroglobulin changed to 83.0 +/- 0.5 A or 85.4 +/- 0.5 A, respectively, and that of ovomacroglobulin to 93.0 +/- 0.5 A or 87.1 +/- 0.5 A. The circular dichroic spectra of native alpha-macroglobulin and ovomacroglobulin exhibited a negative band at around 215 nm, indicating the presence of beta-structure. Reaction of the two macroglobulins with methylamine resulted in a slight decrease in the ellipticity and reaction with proteinases led to a slight increase. The electron micrographic images of native alpha-macroglobulin and ovomacroglobulin can be described as deformed rings for the former and rugby balls for the latter. A common characteristic feature of the two molecules was that the central parts of the molecules were only thinly occupied by subunit. After reaction of macroglobulins with proteinases, the void spaces became partially filled and their overall shape more rectangular. Methylamine treatment caused a structural change only in alpha-macroglobulin but not in ovomacroglobulin. The difference in the susceptibility of the macroglobulins to methylamine was taken as an indication of evolutional divergence of the two homologous proteins within the last 300 million years.     

The X-ray structure determination of bovine carbonmonoxy hemoglobin at 2.1 A resoultion and its relationship to the quaternary structures of other hemoglobin crystal froms

Crystallographic studies of the intermediate states between unliganded and fully liganded hemoglobin (Hb) have revealed a large range of subtle but functionally important structural differences. Only one T state has been reported, whereas three other quaternary states (the R state, B state, and R2 or Y state) for liganded Hb have been characterized; other studies have defined liganded Hbs that are intermediate between the T and R states. The high-salt crystal structure of bovine carbonmonoxy (CO bovine) Hb has been determined at a resolution of 2.1 A and is described here. A detailed comparison with other crystallographically solved Hb forms (T, R, R2 or Y) shows that the quaternary structure of CO bovine Hb closely resembles R state Hb. However, our analysis of these structures has identified several important differences between CO bovine Hb and R state Hb. Compared with the R state structures, the beta-subunit N-terminal region has shifted closer to the central water cavity in CO bovine Hb. In addition, both the alpha- and beta-subunits in CO bovine Hb have more constrained heme environments that appear to be intermediate between the T and R states. Moreover, the distal pocket of the beta-subunit heme in CO bovine Hb shows significantly closer interaction between the bound CO ligand and the Hb distal residues Val 63(E11) and His 63(E7). The constrained heme groups and the increased steric contact involving the CO ligand and the distal heme residues relative to human Hb may explain in part the low intrinsic oxygen affinity of bovine Hb.     

Hb(alphaalpha,betabeta): a novel fusion construct for a dimeric, four-domain hemoglobin

Hemoglobin-based blood substitutes are one of the options available to derive a resuscitating fluid taking into account clinical and physiological demands. In this paper we investigated a novel protein, Hb(alphaalpha,betabeta) obtained as a combination of two homodimers alpha(2) and beta(2) both derived from a fusion gene containing two alfa chains or two beta chains, each respectively coupled via a specific linker. The construct here described is thus a novel heterodimeric hemoglobin carrying four heme groups. The protein cannot dissociate into dimers, as demonstrated by its absence of reactivity versus haptoglobin, and is expected to have a relatively long circulating half-life. The modification does not increase the autoxidation rate, but increases the oxygen affinity, due to a destabilization of the T quaternary state. Characterization of the biochemical properties of this protein in comparison with HbA is reported.     

Structural analysis of the minor human hemoglobin components: Hb AIa1, Hb AIa2 and Hb AIb

Human hemolysate contains several minor hemoglobin components, including Hb AIa1, Hb AIa2, Hb AIb and Hb AIc which are post-translational modifications of the major component, Hb A0. Hb AIc is known to contain glucose attached to the N terminus of the beta chains by a ketoamine linkage. We separated the alpha and beta globin chains from purified Hb AIa1, Hb AIa2 and Hb AIb by ion-exchange chromatography. The beta chains were reducible by sodium borohydride and gave a positive thiobarbituric acid test. These results indicated that they are modified by ketoamine-linked carbohydrate. In addition, phosphate analysis revealed 1.5 phosphate residue associated with each beta AIa1 chain and 1 phosphate residue with each beta AIa2 chain. Hb AIa1, Hb AIa2 and Hb AIb were all found to be contaminated by non-globin proteins. Protein-sequencing approaches demonstrated that the N termini of beta AIa1, beta AIa2 and beta AIb were blocked. In support of this conclusion, analysis of tryptic digests of beta AIa2 and B AIb revealed modified N-terminal peptides. We conclude that, like Hb AIc, components Hb AIa1, Hb AIa2 and Hb AIb also contain a sugar moiety linked to the N terminus of the beta chain.