Cheong Hoong Diong

Evolutionary genetics of the suiformes as reconstructed using mtDNA sequencing

We have amplified and sequnced the entire mitochondrial DNA cytochromeb gene from four species of Suidae: babirusa, warthog, bearded pig, and some specimens belonging to different subspecies and populations of wild and domestic pigs (Sus scrofa). These sequences were aligned with additional mammalian sequences retrieved from the literature and were used to obtain phylogenetic trees of the Suiformes (Artiodactyla). Several species of Carnivora, Perissodactyla. Cetacea, and other Artiodactyla were used as outgroups. Molecular phylogenetic relationships among the Suiformes reflect their current taxonomy: Hippopotamidae, Tayassuidae, and Suidae are separated by deep genetic gaps, and the division of the Suidae into the subfamilies Babyrousinae., Phacochoerinae, and Suinae has strong genetic correlates. Cytochromeb sequences show differences among Asian and Western populations ofSus scrofa, agreeing with other genetic information (karyotypes blood groups, and protein variability). The two Italian subspecies of wild boar have unique mtDNA cytochromeb haplotypes. The evolutionary rates of cytochromeb sequences are different at transitions versus transversions as well as at first, second, and third positions of codons. Therefore, these classes of substitutions reached different levels of mutational saturation. Only transversions and the conservative first and second position substitutions are linearly related to genetic distances among the Suiformes. Therefore, divergence times were computed using unsaturated conserved nucleotide substitutions and calibrated using paleontological divergence times between some Artiodactyla. Transversions apparently evolve at remarkably regular rates in ungulate taxa which have accumulated less than 20% estimated sequence divergence, corresponding to about 40–45 million years of independent evolution. Molecular, information suggests that Hippopotamidae and Tayassuidae are not closely related (as stated by Pickford, 1986, 1989, 1993) and that the origin of babirusa and warthog (about 10–19 and 5–15 million years ago, respectively) is more recent than supported by current evolutionary reconstructions. The inferred origin of bearded pig is about 2.1 million years old, and genetic divergence among differentSus scrofa populations is probably a Pleistocene event. The addition of new sequences of Suiformes does not help in resolving the phylogenetic position ofHippopotamus amphibius, which shows weak but recurrent linkages with the cetacean evolutionary lineage.

New phylogenetic perspectives among species of South-east Asian wild pig (Sus sp.) based on mtDNA sequences and morphometric data

There are more taxa of wild pig in South-east Asia (SEA) than in any other comparable area in the world, but the number of species and subspecies is still uncertain. The taxonomy of some wild pig populations distributed in Malaysia, Indonesia and the Philippines, was investigated using molecular and morphometric techniques. Our results suggest the existence of two main evolutionary clades that are likely to have diverged during the Pliocene in SEA: one including wild pig populations distributed in the Philippines (Sus cebifrons) and Sulawesi (S. celebensis); the other including the Indonesian and Malaysian bearded pigs (S. barbatus), and the widespread Eurasian wild boar (S. scrofa). A possible scenario for pig speciation in SEA is developed, and the need for a taxonomic revision of bearded pigs suggested, particularly concerning the taxonomic status of S. b. ahoenobarbus from Palawan Island, and the existence a new species distributed in the Tawi Tawi Islands (Philippines). Unexpectedly, bearded pigs in the Malay Peninsula are closely related to the Bornean population, but distinct from Sumatran S. barbatus, and they should be considered as belonging to a different subspecies.

Numbat nirvana: conservation ecology of the endangered numbat (Myrmecobius fasciatus) (Marsupialia : Myrmecobiidae) reintroduced to Scotia and Yookamurra Sanctuaries, Australia

Abstract. Despite a vigorous reintroduction program between 1985 and 2010, numbat populations in Western Australia are either static or declining. This study aimed to document the population ecology of numbats at two sites that are going against this trend: Scotia Sanctuary in far western New South Wales and Yookamurra Sanctuary in the riverland of South Australia. Scotia (64 659 ha) and Yookamurra (5026 ha) are conservation reserves owned and managed by the Australian Wildlife Conservancy and where numbats were reintroduced in 1999 and 1993 respectively. Both sites have large conservation-fence-protected introduced-species-free areas where there are no cats (Felis catus) or red foxes (Vulpes vulpes). Numbats were sourced from both wild and captive populations. From small founder populations, the Scotia numbats are now estimated to number 169 (113–225) with 44 at Yookamurra. Radio-collared individuals at Scotia were active between 13 and 31°C. Females had home ranges of 28.3 ± 6.8 ha and males 96.6 ± 18.2 ha, which leads to an estimated sustainable population or carrying capacity of 413–502 at Scotia. Captive-bred animals from Perth Zoo had a high mortality rate upon reintroduction at Scotia due to predation by raptors and starvation. The habitat preferences for mallee with a shrub understorey appear to be driven by availability of termites, and other reintroduced ecosystem engineers appear to have been facilitators by creating new refuge burrows for numbats. This study shows that numbats can be successfully reintroduced into areas of their former range if protected from introduced predators, and illustrates the difficulties in monitoring such cryptic species.

Changes in in-vivo autofluorescence spectra at different periods in rat colorectal tumor progression

The study focuses on the Laser-Induced Autofluorescence (LIAF) diagnosis technique to identify early tumor tissue. 442nm light from a Helium-Cadmium Laser is excited to investigate the spectra of the in vivo normal and tumor rat colorectal tissues. The experiment results show that the LIAF spectra of the normal and tumor colorectal tissues exhibit the significant differences. The results are potentially useful for the development of a clinical study for early colorectal cancer diagnosis.

Laser-induced autofluorescence of human colonic tissues

The purpose of this study is to perform a preliminary evaluation of the diagnostic potential of laser-induced autofluorescence spectroscopy for colonic tumors using fluorescence intensity ratios at specific wavelengths. Measurements were made on normal mucosa and adenocarcinoma of human colon tissues. Each tissue section was examined using an optical probe consisting of a central fiber for delivering the excitation laser and a fiber bundle for detection of the fluorescence. Using different wavelengths of a CW mixed-gas laser, we measured and analyzed the LIAF spectra of tissues through a polychromator coupled with a CCD detector. It can be found that in the range of 520-620 nm, the spectral shapes of tumor tissues are very similar to the normal tissue spectra, and the autofluorescence intensities of normal tissues are about threefold higher than those of tumor tissues. However, in the range of 625- 720nm, the autofluorescence intensities of tumor tissues are higher than those of normal tissue. The spectral characteristics peaks arising from endogenous porphyrins can be observed in some tumor tissues. The preliminary results show that the autofluorescence intensity ratio of I580/I630 or I580/I680 can be used to distinguish colonic tumors from normal tissues with good accuracy.

Application of laser induced autofluorescence spectra detection in human colorectal cancer screening

We investigated 48 normal patients and 25 diseased patients using our laser-induced autofluorescence spectra detection system during their regular colonoscopy. The colon and rectum mucosa autofluorescence were excited by 405 nm continue wavelength laser. We observed that cancer or diseased colorectal mucosa, their autofluorescence spectra are significantly different from normal area. The autofluorescence spectra intensity at about 500 nm was been used for our intensity ratio characteristics intensity for our diagnostic algorithm. The intensity ratios of RI-680/I-500 and RI-630/I-500 were performed to identify the detection area. From experimental result we concluded that both intensity ratios of RI-680/I-500 and RI-630/I-500 as guidelines can detect cancerous and polyps disease completely. Our investigation provided some useful insight for laser induced autofluorescence spectra as a diagnosis technique for clinical application.

Changes in autofluorescence emission intensities of human colonic tissues due to photobleaching process

Changes in autofluorescence intensities at 550, 580, 680 and 720 nm as functions of incident intensity and exposure time were measured in normal mucosa and adenocarcinomatous of human colonic tissues when excited by the wavelengths of 457.9, 488, 514.5 and 632.8 nm, respectively. The obtained results show that the photobleaching process of the autofluorescence follows a double-exponential function. The slower decay rates of the photobleaching at 550 and 580 nm emissions could be found in normal tissues compared to those in tumor tissues, however, the faster decay times at 680 and 720 nm emissions were also found in normal tissues. It appears that the quantitative measurements of photobleaching processes may provide a method to evaluate the fractional contribution of the autofluorescence from different layers in the colon tissues. The evaluation of temporal behavior of photobleaching processes of autofluorescence emissions may also reveal the different accumulated concentrations of endogenous fluorophores between normal and tumor tissues.

Comparison of human colorectal normal tissue with cancerous tissue autofluorescence image by optical sectioning with a confocal laser-scanning microscope

We investigated normal and cancerous human colorectal tissues (fresh thick biopsy specimens) using Olympus Confocal laser scanning biological microscope (FV300). The different layers of autofluorescence images of the specimen were captured by 488 nm laser scanning and sectioning. Optical sectioning can be performed in the vertical plane. Laser scanning can be performed in the horizontal plane. By comparing the autofluorescence image of the normal colorectal tissue with cancerous tissue, the structures of the optical sectioning image layer were found to be significantly different. We have also obtained fibrous autofluorescence image inside tissue specimen. Our investigation may help provide some useful insight to other autofluorescence research studies like laser induced autofluorescence spectra of human colorectal tissue study as a diagnosis technique for clinical application.

Laser-induced fluorescence spectrum of human colonic tissues by Monte Carlo modeling

Based on the microscopic properties of colonic tissues, a five-layer colon optical model was developed to calculate the excitation light distribution in the tissue and the fluorescence escape function from the tissue by Monte Carlo simulations. The theoretically modeled fluorescence spectrum fits well to the experimental results, demonstrating that the microscopic properties of tissue applied in the colon optical model can be quantitatively correlated with the macroscopic autofluorescence measurements.

Light distribution in human lung tissue at 413.1 nm in vitro

By using an isotropic fiber-optic probe together with an accurate mechanical positioning system, the fluence rate distributions (2-D, 3-D) were measured in normal and squama- carcinomatous human lung tissues in vitro for incident irradiance of 22 mW/cm2