A new species of <i>Leptolalax</i> (Anura: Megophryidae) from northern Vietnam

We describe a new, medium-sized Leptolalax species from Vietnam. Leptolalax petrops sp. nov. is distinguished from its congeners by a combination of having a medium-sized body (23.6-27.6 mm in 21 adult males, 30.3-47.0 mm in 17 adult females), immaculate white chest and belly, no distinct black markings on the head, highly tuberculate skin texture, toes lacking webbing and with narrow lateral fringes, and a call consisting of an average of four notes and a dominant frequency of 5.6-6.4 kHz (at 24.5-25.3 °C). Uncorrected sequence divergences between L. petrops sp. nov. and all homologous DNA sequences available for the 16S rRNA gene are >8%.

Five new, microendemic Asian Leaf-litter Frogs (Leptolalax) from the southern Annamite mountains, Vietnam

The Leptolalax applebyi group of Asian leaf-litter frogs currently comprises four species of particularly small-bodied (<40 mm SVL) species distributed in the Central Highlands of Vietnam and northeastern Cambodia. In addition to their small size, the group is characterized by their morphological and genetic similarities, as well as their breeding habitat at headwaters of small mountain streams and seeps. A recent study suggested that at least two-thirds of the diversity of the group remained hidden within morphologically cryptic lineages. We expand upon the molecular, morphometric, and acoustic data and formally delineate and describe five of these lineages as distinct species: Leptolalax ardens sp. nov., Leptolalax kalonensis sp. nov., Leptolalax pallidus sp. nov., Leptolalax maculosus sp. nov., and Leptolalax tadungensis sp. nov. Due to habitat loss, the current ranges of these species are likely to be a fraction of their historical extent and under continued threat from deforestation.

A new species of Leptolalax (Anura: Megophryidae) from Vietnam and Cambodia

We describe a new, medium-sized Leptolalax species from the Kon Tum Plateau of Vietnam and adjacent Cambodia. Leptolalax isos sp. nov. is distinguished from its congeners by a combination of an absence of distinct dark brown/black dorsolateral markings; toes with rudimentary webbing, wide lateral dermal fringes in males and weak or absent lateral dermal fringes in females; most males with wide lateral dermal fringes on Finger II, a body size of 23.7-27.9 mm in 38 adult males and 28.6-31.5 mm in 9 adult females, near immaculate white chest and belly; absence of white speckling on the dorsum; and a call consisting of 2-3 notes with a dominant frequency of 5.9-6.2 kHz (at 22.4-22.8º C). Uncorrected sequence divergences between L. isos sp. nov. and all homologous 16S rRNA sequences available are &gt;10%. At present, the new species is known from montane evergreen forest between ~650-1100 m elevation in northeastern Cambodia and central Vietnam. Habitat within the range of the new species is threatened by deforestation and upstream hydroelectric dams.

Undiagnosed cryptic diversity in small, microendemic frogs (Leptolalax) from the Central Highlands of Vietnam

A major obstacle in prioritizing species or habitats for conservation is the degree of unrecognized diversity hidden within complexes of morphologically similar, "cryptic" species. Given that amphibians are one of the most threatened groups of organisms on the planet, our inability to diagnose their true diversity is likely to have significant conservation consequences. This is particularly true in areas undergoing rapid deforestation, such as Southeast Asia. The Southeast Asian genus Leptolalax is a group of small-bodied, morphologically conserved frogs that inhabit the forest-floor. We examined a particularly small-bodied and morphologically conserved subset, the Leptolalax applebyi group, using a combination of molecular, morphometric, and acoustic data to identify previously unknown diversity within. In order to predict the geographic distribution of the group, estimate the effects of habitat loss and assess the degree of habitat protection, we used our locality data to perform ecological niche modelling using MaxEnt. Molecular (mtDNA and nuDNA), acoustic and subtle morphometric differences revealed a significant underestimation of diversity in the L. applebyi group; at least two-thirds of the diversity may be unrecognised. Patterns of diversification and microendemism in the group appear driven by limited dispersal, likely due to their small body size, with several lineages restricted to watershed basins. The L. applebyi group is predicted to have historically occurred over a large area of the Central Highlands of Vietnam, a considerable portion of which has already been deforested. Less than a quarter of the remaining forest predicted to be suitable for the group falls within current protected areas. The predicted distribution of the L. applebyi group extends into unsurveyed watershed basins, each potentially containing unsampled diversity, some of which may have already been lost due to deforestation. Current estimates of amphibian diversity based on morphology alone are misleading, and accurate alpha taxonomy is essential to accurately prioritize conservation efforts.

Electronic imaging system incorporating a hand-held fundus camera for canine ophthalmology

An electronic imaging system incorporating a hand-held fundus camera was used to collect images of the canine ocular fundus. The electronic imaging system comprised a hand-held fundus camera, an IBM personal computer (PC 350), Microsoft Windows NT 4.0, Adobe Photoshop, and a color printer (Tektronix Phaser 550) and was used to store, edit, and print the images captured by the fundus camera. Hand-held fundus cameras are essential for use in canine ophthalmology. The Nidek NM-100 hand-held fundus camera digitalizes images, enabling their direct transfer into reports and their storage on writeable CDs.

Extrathyroidally mediated changes in circulating thyroid hormone concentrations in the male rat following administration of an experimental oxyacetamide (FOE 5043)

Evidence of increased hepatic metabolizing capacity coupled with reductions in serum thyroxine (T4) levels were noted in the rat during preliminary toxicity studies with FOE 5043, an oxyacetamide with herbicidal properties. These findings were consistent with reports in the literature suggesting that declines in T4 as a result of exposure to various classes of chemicals may be mediated extrathyroidally, such as through chemical induction of hepatic thyroid hormone metabolism. To examine this question with respect to FOE 5043, male rats were surgically thyroidectomized and provided thyroid hormone replacement therapy via implanted osmotic minipumps capable of maintaining a T4/triiodothyronine (T3) serum concentration for approximately 4 weeks at a level comparable to that of euthyroid controls. Seven days after minipump implantation, thyroidectomized + T4/T3 (TX + T4/T3) and nonthyroidectomized intact rats (NTX) were fed diets containing 0, 25, 1000, or 3000 ppm FOE 5043 for up to 3 weeks. Dose-related and equivalent declines in total and free serum T4 levels in both TX + T4/T3 and NTX rats were measured at Weeks 1, 2, and 3. Alterations in thyrotropin, total, free, and reverse serum T3 levels were also noted in both TX and NTX animals; however, a compound-related trend was difficult to discern and, when compared to the T4 response, the changes were markedly less consistent with respect to both time and dose. Additionally, dose-related increases in absolute and relative liver weights were measured in both TX + T4/T3 and NTX animals. As the only source of thyroid hormone in the TX + T4/T3 animals was that provided by the pump, these data suggest that FOE 5043-induced alterations in serum thyroid hormone levels, most notably T4, are being mediated indirectly, possibly as a result of increased hepatic metabolism, rather than through a direct effect on the thyroid gland.

Neurotensin stimulates growth of small intestine in rats

Neurotensin has many actions on digestive tract motility and secretion and stimulates pancreatic growth. We examined effects of chronic administration of neurotensin on growth of small intestine and colon. Four groups of 10 rats were injected with saline or neurotensin (33, 100, or 300 micrograms/kg) every 8 h for 5 days. The small intestine was divided into four segments of equal length, weighed, and assayed for DNA, protein, and brush-border digestive enzymes. The colon was weighed and assayed for DNA and protein. Neurotensin caused dose-related increases in growth of small intestine; at the highest dose, similar increases in weight (12-20%), DNA (23-35%), and protein content (33-39%) occurred in each segment of small intestine. Maltase, sucrase, and leucine aminopeptidase (but not lactase) contents were also significantly increased after neurotensin, but the largest effects were seen in the proximal small intestine. Neurotensin had no effect on weight, DNA, or protein content of the colon. These results suggest a role for neurotensin in regulating growth of small intestine.

Interaction of neurotensin with caerulein or secretin on digestive tract growth in rats

Because neurotensin may potentiate exocrine pancreatic secretory responses to cholecystokinin and secretin, we examined interactions of neurotensin with caerulein or secretin on growth of pancreas, stomach, small intestine, and colon. Rats were injected with saline, neurotensin (100 micrograms/kg), caerulein (0.67 micrograms/kg), secretin (100 micrograms/kg), or neurotensin plus caerulein or secretin every 8 h for 5 days. Pancreas, stomach, small intestine, and colon were weighed and assayed for DNA, protein, and digestive enzymes. Although neurotensin increased pancreatic weight (P less than 0.01), DNA (P less than 0.01), and protein content (P less than 0.05) by 20-30%, it had less than additive effects on responses to caerulein and secretin. Neurotensin had no effects on pancreatic enzymes or on responses to caerulein or secretin. Neurotensin alone had no effects on growth of the oxyntic gland area or antrum but inhibited increases in antral weight, DNA, and protein caused by secretin. Neurotensin increased small intestine weight (9%, P less than 0.05) and protein content (23%, P less than 0.01). Secretin also increased weight (22%), DNA (29%), and protein content (48%) of the small intestine (all P less than 0.01), but neurotensin and secretin together had less than additive effects. Our results suggest that neurotensin inhibits rather than potentiates certain growth effects of caerulein or secretin on the pancreas and other organs.

Effect of neurotensin on pancreatic and gastric secretion and growth in rats

Plasma levels of neurotensin are increased by ingestion of fat, making this peptide a candidate for mediation of pancreatic adaptation to dietary fat. We examined the effects of doses of neurotensin on pancreatic secretion and growth to determine whether doses stimulating secretion also increased pancreatic growth and lipase content in rats. Because neurotensin inhibits gastric secretion in other species, we also measured its effects on gastric secretion and growth. In conscious rats, neurotensin (33, 100, and 300 micrograms kg-1 subcutaneously in gelatin) produced dose-related increases in pancreatic amylase output and decreases in basal gastric secretion. Duration of acid inhibition by neurotensin was longer than stimulation of amylase secretion. Chronic administration of the same doses of neurotensin to groups of rats every 8 h for 5 days produced small but statistically significant trophic effects on the pancreas. The highest dose of neurotensin significantly increased pancreatic weight (16%) and content of DNA (12%), protein (17%), and chymotrypsinogen (60%) but did not affect amylase or lipase content. There were no effects of neurotensin on any measurement of oxyntic or pyloric gland area growth. We conclude that although neurotensin stimulates both pancreatic secretion and growth, it is not the mediator of fat-induced pancreatic adaptation.