Determination of thick and thin fibres distribution in Sunda porcupine dorsal skin (Hystrix javanica) using Picrosirius red staining.

The complexity of the Sunda porcupine skin has become an important topic due to the unique characteristics of its quill follicles. The structure and chemical composition of the skin has affected many physiological and other conditions. Generally, quills are larger, stronger and stiffer than hair; therefore, the skin structure needs to adapt to support their physiology. The strength of the skin is determined by its collagen composition and arrangement; therefore, this study aims to analyse the composition and distribution of thick and thin fibres based on the specific characteristics of Sunda porcupine skin under polarized light using picrosirius red staining. The skin samples used were from the thoracodorsal and lumbosacral regions of eight Sunda porcupine adults. The histological staining was carried out using the picrosirius red method, while the samples were observed under a polarized light microscope and analysed with software. The results showed that the skin is composed of 36%-65% thick fibres, 20%-35% thin fibres and small amounts of other types with the lumbosacral region having higher compositions of thick and thin fibres than those in the thoracodorsal region. Furthermore, the thoracodorsal and lumbosacral regions have the highest composition of thick fibre in the deeper dermis and quill follicle, respectively. These demonstrated that the complexity of the skin structure of Sunda porcupine due to its quill derivates correlated with its collagen composition and distribution.

Fatty acid composition profiling in the dorsal skin of Sunda porcupine (Hystrix javanica).

The fatty acid composition in the skin of Sunda porcupine (Hystrix javanica) is an interesting topic due to the special features of quills, especially in the dorsal region. Therefore, this study aims to analyze the composition of fatty acids in the dorsal region of Sunda porcupine skin. It was conducted using skin samples of the thoracodorsal and lumbosacral regions taken by biopsies and from frozen specimens. The skin lipid was extracted and then derivatized into fatty acid methyl ester before analyzing with gas chromatography mass spectrometry. The results showed that the skin is composed of up to 25 fatty acids ranging from C12 to C25 with various types but only 16 were found in both regions and sexes. Fatty acids with an antibacterial effect were found abundantly, such as oleic, palmitic, stearic, and linoleic acids. The total abundance in the thoracodorsal region was higher than lumbosacral, while the composition in male was higher than in female. Based on the results, the fatty acid composition in the dorsal skin region of Sunda porcupine consists of at least 16 types ranging from C12-C25. Additionally, the region and sex were observed to contribute significantly to the variation in skin fatty acid composition.

Localization of uncoupling protein 1 (UCP-1) in the sebaceous gland of the dorsal region in the Sunda porcupine (Hystrix javanica).

Uncoupling protein 1 (UCP-1) was believed to be an exclusive protein found in the brown adipose tissue of small rodents and humans; however, recent studies show that the expression of UCP-1 protein has been found in the sebaceous glands of the mouse tail and human skin. There are a few reports about the presence of UCP-1 in the sebaceous glands of other rodents, such as the Sunda porcupine (Hystrix javanica), a wild spiny rodent commonly found in Indonesia with a large sebaceous gland. The aim of this study was to identify the presence of UCP-1 in the sebaceous glands on the skin of the Sunda porcupine. The skin from three regions (thoracodorsal, lumbosacral and apex caudal) of eight adult Sunda porcupines was used to detect UCP-1-immunopositive cells through immunohistochemistry. All three regions were found immunopositive to anti-UCP-1 antibody in the sebaceous gland of quill and hair follicles, and the epidermal layer in quill and hair follicles with various intensities. The result of immunohistochemistry revealed that the thoracodorsal and apex caudal region was the most intense immunoreaction followed by the lumbosacral region. These findings proved that the presence of UCP-1 was also identified in the sebaceous glands of other rodent (Hystrix javanica) and regions of the body, which has not been reported previously.

Morphological evaluation of polysaccharide content and collagen composition during cutaneous wound healing in the Sunda porcupine (Hystrix javanica).

Wound healing in the Sunda porcupine is believed to occur quickly, although the wound is large and severe. Wound enclosure involves many processes to restore the lost or damaged skin structure where conjugated polysaccharide-protein and collagen, as the main components deposited in wound tissue to restore it. The aim of this study was to evaluate alteration of polysaccharide contents and collagen in untreated full-thickness wound healing in the thoracodorsal and lumbosacral regions in the Sunda porcupines. Histological analysis was performed by periodic acid Schiff, alcian blue pH 2.5, picrosirius red staining method and Low Vacuum Scanning Electron Microscope (LV-SEM) imaging to obtain the fundamental data of healing process. Wound healing began with re-epithelization followed by progressive wound contraction with 4 overlapping stages in about 30-50 days until the wound closed (21-30 days in thoracodorsal and 30-50 days in lumbosacral). Neutral polysaccharide was more widely distributed compared to the acid polysaccharide in almost all stages of wound healing. The ratio of collagen I to III appeared to be higher in the thoracodorsal region than the lumbosacral region during healing process. LV-SEM imaging showed changes in connective tissue structure in the wound border and granulation tissue which appeared abundant and mixed of thin and thick fiber. In conclusion, cutaneous full thickness wound healing in the Sunda porcupine occurred faster in the thoracodorsal region, which might be correlated to the role of neutral polysaccharide and a high ratio of collagen I to III.

The dorsal skin structure contributes to the surface bacteria populations of Sunda Porcupine (Hystrix javanica).

Skin becomes the largest organ in the body and protects its own inner layer. The structure and chemical composition of the skin contribute to skin condition and affect the habitat of certain bacteria. The Sunda Porcupine is one of endemic animals of Indonesia which possesses quill as the main derivate of its skin and as a defence tool against predators. The present study used nine adults (five females and four males) of Sunda Porcupine and aimed to observe the correlation of skin structure with bacterial population at the surface level. The skin was wavy due to the protrusion of quill follicle orifices on the skin surface and formed clusters. The skin of Sunda Porcupine was also wrinkled and had a lot of flakiness. Histologically, the skin was composed of epidermis, dermis, hypodermis and subcutaneous muscle. The quill follicles and their properties were the dominant structure component of the skin. No sweat gland was observed in the skin of the Sunda Porcupine, and sebaceous gland was found only around quill and hair follicles. The bacterias identified in the skin were Staphylococcus aureus, S. epidermidis, Micrococcus sp. and Salmonella sp. When compared, the bacterial population was higher in the lumbosacral region than in the thoracodorsal region, but the difference was not significant. The density of quill clusters was negatively correlated to the bacterial population. It was suggested the structure of the skin has contribution to bacterial population in dorsal trunk of the Sunda Porcupine.

Nutritional ecology of wild Bornean orangutans (Pongo pygmaeus wurmbii) in a peat swamp habitat: Effects of age, sex, and season.

The spatial and temporal variation in food abundance has strong effects on wildlife feeding and nutrition. This variation is exemplified by the peatland forests of Central Kalimantan, which are characterized by unpredictable fruiting fluctuations, relatively low levels of fruit availability, and low fruit periods (<3% of trees fruiting) that can last nearly a year. Challenged by these environments, large, arboreal frugivores like orangutans must periodically rely on non-preferred, lower-quality foods to meet their nutritional needs. We examined variation in nutrient intake among age-sex classes and seasons over a 7-year period at the Tuanan Orangutan Research Station in Central Kalimantan. We conducted 2,316 full-day focal follows on 62 habituated orangutans (Pongo pygmaeus wurmbii). We found differences in total energy and macronutrient intake across age-sex classes, controlling for metabolic body mass. Intake of both total energy and macronutrients varied with fruit availability, and preference of dietary items increased with their nutritional quality. Foraging-related variables, such as day journey length, travel time, and feeding time, also varied among age-sex classes and with fruit availability. Our results add to the growing body of literature suggesting that great variation in foraging strategies exists among species, populations, and age-sex classes and in response to periods of resource scarcity. RESEARCH HIGHLIGHTS: The spatial and temporal variation in food abundance has strong effects on wildlife feeding and nutrition. Here we present the first long term study of the effects of variation in fruit availability and age/sex class on nutritional ecology of wild Bornean orangutans. We examined variation in nutrient intake of wild orangutans in living in a peat swamp habitat over a 7-year period at the Tuanan Orangutan Research Station in Central Kalimantan. We conducted 2,316 full-day focal follows on 62 habituated orangutans (Pongo pygmaeus wurmbii). We found differences in total energy and macronutrient intake across age-sex classes, controlling for metabolic body mass. Intake of both total energy and macronutrients varied with fruit availability, and preference of dietary items increased with their nutritional quality. Foraging-related variables, such as day journey length, travel time, and feeding time, also varied among age-sex classes and with fruit availability. Our results add to the growing body of literature suggesting that great variation in foraging strategies exists among species, populations, and age-sex classes and in response to periods of resource scarcity.

Nutritional Differences between Two Orangutan Habitats: Implications for Population Density.

Bottom-up regulatory factors have been proposed to exert a strong influence on mammalian population density. Studies relating habitat quality to population density have typically made comparisons among distant species or communities without considering variation in food quality among localities. We compared dietary nutritional quality of two Bornean orangutan populations with differing population densities in peatland habitats, Tuanan and Sabangau, separated by 63 km. We hypothesized that because Tuanan is alluvial, the plant species included in the orangutan diet would be of higher nutritional quality compared to Sabangau, resulting in higher daily caloric intake in Tuanan. We also predicted that forest productivity would be greater in Tuanan compared to Sabangau. In support of these hypotheses, the overall quality of the diet and the quality of matched dietary items were higher in Tuanan, resulting in higher daily caloric intake compared to Sabangau. These differences in dietary nutritional quality may provide insights into why orangutan population density is almost two times greater in Tuanan compared to Sabangau, in agreement with a potentially important influence of diet quality on primate population density.