Isolation,purification and characterization of pepsin soluble collagen isolated from silvertip shark (Carcharhinus albimarginatus) skeletal and head bone

Type II pepsin soluble collagens (PSC) were isolated from skeletal and head bone of silvertip shark; and examined for their biochemical and structural properties. Among the raw materials, the protein content (8.99%) was high in skeletal bone and the ash content (28%) was high in head bone. After the collagen extraction, the raw materials contained higher amount of ash content ranging from 82 to 88%. The hydroxyproline content of skeletal and skeletal PSC (30 and 113 mg/g) was higher than those head and head PSC. Both collagens were composed of two different α-chains (α₁- and α₂-chains) and were characterized as type II collagen. Amino acid analysis of skeletal and head PSC indicated imino acid contents of 156 and 175 amino acid residues per 1000 residues, respectively. Similar, Fourier transform infrared spectra of SCII and HCII were observed, which suggested that the isolation process did not affect the secondary structure and molecular order of collagen, particularly the triple–helical structure. Denaturation temperature of skeletal PSC (31 °C) was higher than that of head PSC. SEM microstructure of the collagens depicted a porous, fibrillary and multi-layered structure. These results suggested that the PSC isolated from skeletal and head bone of silvertip shark were found to be suitable biomaterial in commercial applications as alternatives to mammalian collagen.     

Effects of Including Misidentified Sharks in Life History Analyses: A Case Study on the Grey Reef Shark Carcharhinus amblyrhynchos from Papua New Guinea

Fisheries observer programs are used around the world to collect crucial information and samples that inform fisheries management. However, observer error may misidentify similar-looking shark species. This raises questions about the level of error that species misidentifications could introduce to estimates of species’ life history parameters. This study addressed these questions using the Grey Reef Shark Carcharhinus amblyrhynchos as a case study. Observer misidentification rates were quantified by validating species identifications using diagnostic photographs taken on board supplemented with DNA barcoding. Length-at-age and maturity ogive analyses were then estimated and compared with and without the misidentified individuals. Vertebrae were retained from a total of 155 sharks identified by observers as C. amblyrhynchos. However, 22 (14%) of these were sharks were misidentified by the observers and were subsequently re-identified based on photographs and/or DNA barcoding. Of the 22 individuals misidentified as C. amblyrhynchos, 16 (73%) were detected using photographs and a further 6 via genetic validation. If misidentified individuals had been included, substantial error would have been introduced to both the length-at-age and the maturity estimates. Thus validating the species identification, increased the accuracy of estimated life history parameters for C. amblyrhynchos. From the corrected sample a multi-model inference approach was used to estimate growth for C. amblyrhynchos using three candidate models. The model averaged length-at-age parameters for C. amblyrhynchos with the sexes combined were L¯∞ = 159 cm TL and L¯0 = 72 cm TL. Females mature at a greater length (l₅₀ = 136 cm TL) and older age (A₅₀ = 9.1 years) than males (l₅₀ = 123 cm TL; A₅₀ = 5.9 years). The inclusion of techniques to reduce misidentification in observer programs will improve the results of life history studies and ultimately improve management through the use of more accurate data for assessments.     

Scale bearing chrysophytes from Papua New Guinea

The scaled chrysophytes from Papua New Guinea were studied for the first time. Twenty two taxa of Chrysophyceae and Synurophyceae are reported. Species diversity was highest in black- and mixed water lakes and swamps of the Sepik floodplain. Most surprisingly. the oligotrophic highland lakes were very poor in chrysophytes.     

Blood parasites of mammals from Papua New Guinea

Thin blood smears were collected from 126 mammals representing four genera of marsupials and six genera of murid rodents. A species of Hepatozoon was discovered in the New Guinea spiny bandicoot (Echymipera kalubu), trypanosome infections were found in three genera of rodent hosts and the prevalence of a rickettsial parasite of the genus Grahamella was recorded in rodents from the genera Rattus and Melomys. Dried blood samples also were taken and screened serologically for antibodies to arenavirus infection but with negative results.     

Contributions to the Cladocera fauna from Papua New Guinea

Twenty-eight taxa of the Cladocera are identified in collections from Papua New Guinea, 17 being new records for New Guinea, bringing the total number of Cladocera taxa reported for this region to 39. Most of the taxa are circumtropical. One species (Sarsilatona papuana) is endemic to Papua New Guinea and northern Australia. The species list includes two species that are normally listed as Holarctic:Alonella nana andAlona rustica. Widespread genera such asDaphnia, Pleuroxus, Disparalona, Acroperus were strikingly absent from the Papua New Guinean material.     

Alpha-thalassemia in Papua New Guinea

Summary A study of the distribution of -thalassemia in Papua New Guinea (PNG) was carried out by DNA analysis. A total of 664 DNA samples were screened for -thalassemia 2 and -thalassemia 1 caused respectively by either deletion of one or both of the duplicated -globin genes. -Thalassemia 2 was detected in high frequencies in coastal and lowland regions where malaria has been holo- to hyperendemic but in low frequencies in non-malarious highland regions. The highest frequency was observed in the north coast of PNG. The distribution of -thalassemia 2 seems to be in accordance with other conditions such as ovalocytosis and G6PD deficiency which are also prevalent in this population, suggesting that they may interact in protection against malaria. However, it appears to be negatively correlated with -thalassemia and -thalassemia 1, the latter being extremely rare in this population. Analysis of the types and subtypes of the single -globin gene deletion revealed a predominance of the –^4.2 type in general, except in some regions in the south where the –^3.7 type is prevalent. The –^3.7 I subtype is the common form of the –^3.7 deletion in the PNG mainland. The –^3.7 III subtype, previously reported to be unique in Melanesians and Polynesians, was detected in an offshore island of PNG. However, this subtype is very rare in Melanesians from the PNG mainland.     

Malaria vectors of Papua New Guinea

Understanding malaria transmission in Papua New Guinea (PNG) requires exact knowledge of which Anopheles species are transmitting malaria and is complicated by the cryptic species status of many of these mosquitoes. To identify the malaria vectors in PNG we studied Anopheles specimens from 232 collection localities around human habitation throughout PNG (using CO₂ baited light traps and human bait collections). A total of 22,970 mosquitoes were individually assessed using a Plasmodium sporozoite enzyme-linked immunosorbent assay to identify Plasmodiumfalciparum, Plasmodiumvivax and Plasmodiummalariae circumsporozoite proteins. All mosquitoes were identified to species by morphology and/or PCR. Based on distribution, abundance and their ability to develop sporozoites, we identified five species as major vectors of malaria in PNG. These included: Anophelesfarauti, Anopheleshinesorum (incriminated here, to our knowledge, for the first time), Anophelesfarauti 4, Anopheleskoliensis and Anophelespunctulatus. Anopheleslongirostris and Anophelesbancroftii were also incriminated in this study. Surprisingly, An. longirostris showed a high incidence of infections in some areas. A newly identified taxon within the Punctulatus Group, tentatively called An. farauti 8, was also found positive for circumsporozoite protein. These latter three species, together with Anopheleskarwari and Anophelessubpictus, incriminated in other studies, appear to be only minor vectors, while Anophelesfarauti 6 appears to be the major vector in the highland river valleys (>1500 m above sea level). The nine remaining Anopheles species found in PNG have been little studied and their bionomics are unknown; most appear to be uncommon with limited distribution and their possible role in malaria transmission has yet to be determined.     

Hematozoa from montane forest birds in Papua New Guinea

Blood smears were examined from 141 montane forest birds of 45 species in southeastern Papua New Guinea. Haemoproteus spp. occurred in 46 (32.6%), Leucocytozoon fringillinarum Woodcock, 1910 in five, Trypanosoma sp. in one and Haemogregarina sp. in one. Intensity of infection by Haemoproteus was highest in those avian species and families with the highest prevalence; increasing altitude had no demonstrable effect on the prevalence of Haemoproteus spp.     

Bioactive Natural Products from Papua New Guinea Marine Sponges

The discovery of novel natural products for drug development relies heavily upon a rich biodiversity, of which the marine environment is an obvious example. Marine natural product research has spawned several drugs and many other candidates, some of which are the focus of current clinical trials. The sponge megadiversity of Papua New Guinea is a rich but underexplored source of bioactive natural products. Here, we review some of the many natural products derived from PNG sponges with an emphasis on those with interesting biological activity and, therefore, drug potential. Many bioactive natural products discussed here appear to be derived from non‐ribosomal peptide and polyketide biosynthesis pathways, strongly suggesting a microbial origin of these compounds. With this in mind, we also explore the notion of sponge‐symbiont biosynthesis of these bioactive compounds and present examples to support the working hypothesis.     

Health research in Papua New Guinea

The Papua New Guinea Institute of Medical Research (PNGIMR) is one of the most respected health research institutions in the developing world, and its studies of the local health problems of PNG have consistently had international relevance. This article examines the structural and philosophical factors that have enabled the success of the PNGIMR, and presents the PNGIMR approach to research as a potential model for other disease-endemic countries. An overview of PNGIMR research into malaria and filariasis is given with selected examples as an introduction to a Trends in Parasitology series on health research in Papua New Guinea.     

Parasitic zoonoses in Papua New Guinea

Relatively few species of zoonotic parasites have been recorded in humans in Papua New Guinea. A greater number of potentially zoonotic species, mostly nematodes, occur in animals but are yet to be reported from humans. Protozoa is the best represented group of those infecting man, with Giardia duodenalis, Cryptosporidium parvum, Cyclospora cayetanesis, Toxoplasma gondii, Sarcocystis spp., Entamoeba polecki, Balantidium coli and, possibly, Blastocystis hominis. The only zoonotic helminths infecting humans include the trematode Paragonimus westermani, the cestodes Hymenolepis nana, H. diminuta and the sparganum larva of Spirometra erinacea, and the nematodes Trichinella papuae and Angiostrongylus cantonensis and, possibly, Ascaris suum. Other groups represented are Acanthocephala (Macracanthorhynchus hirudinaceus)), insects (Chrysomya bezziana, Cimex sp., Ctenocephalides spp.), and mites (Leptotrombidium spp. and, possibly Sarcoptes scabiei, and Demodex sp.). One leech (Phytobdella lineata) may also be considered as being zoonotic. The paucity of zoonotic parasite species can be attributed to long historical isolation of the island of New Guinea and its people, and the absence until recent times of large placental mammals other than pig and dog. Some zoonotic helminths have entered the country with recent importation of domestic animals, in spite of quarantine regulations, and a few more (two cestodes, one nematode and one tick) are poised to enter from neighbouring countries, given the opportunity. Improvement in water supplies, human hygiene and sanitation would reduce the prevalence of many of these parasites, and thorough cooking of meat would lessen the risk of infection by some others.