Localization of photoreceptors in the cercariae of Proterometra macrostoma (Trematoda: Azygiidae)

The swimming behavior of the cercaria of the digenetic trematode Proterometra macrostoma changes in response to light. However, this cercaria does not possess obvious eyes or eyespots. Using behavioral assays, we were able to show that both intact and distome-removed cercariae swim significantly greater vertical distances under dim, red light than under brighter, white light. Electrophysiological experiments confirmed this result and further showed that the transverse band of the tail, known to control cercariae swimming behavior, was necessary and sufficient for the display of the light-dependent swimming behavior. Together, these data show that the distome is not required for light-dependent swimming behavior in P. macrostoma cercariae and indirectly demonstrates the presence of photoreceptors in the transverse band of the cercaria tail.     

Effect of extracellular products of Pseudoalteromonas atlantica on the edible crab Cancer pagurus

Previous studies have shown that injection of extracellular products (ECP) of Pseudoalteromononas atlantica isolated from shell disease-infected edible crabs (Cancer pagurus) into healthy crabs causes rapid death. In this study we examined the nature of the active lethal factor(s) in ECP. Injection of ECP into crabs caused a rapid decline in the total number of circulating hemocytes (blood cells), and the crabs died within 60 to 90 min. The individuals that died showed eyestalk retraction, limb paralysis, and lack of antennal sensitivity, suggesting that the active factor(s) targeted the nervous system. Histopathological investigations showed that affected crabs had large aggregates of hemocytes in the gills, and there was destruction of the tubules in the hepatopancreas. The active factor in ECP was not sensitive to heat treatment (100 degrees C for 30 min) and proteinase K digestion. As lipopolysaccharide (LPS) was a potential candidate for the lethal factor, it was purified from whole P. atlantica bacteria or ECP and subsequently injected into crabs. These crabs had all of the external symptoms observed previously with ECP, such as limb paralysis and eyestalk retraction, and they died within 90 min after challenge, although no significant decline in the number of circulating hemocytes was observed. Similarly, in vitro incubation of hemocytes with purified LPS (1 to 20 microg) from P. atlantica did not result in the clumping reaction observed with ECP but did result in a degranulation reaction and eventual cell lysis. Injection of crabs with Escherichia coli or Pseudomonas aeruginosa LPS (1 microg g of body weight(-1)) did not cause any of the characteristic symptoms observed following exposure to P. atlantica LPS. No mortality of crabs followed the injection of E. coli LPS, but P. aeruginosa LPS caused ca. 80% mortality at 2 h after injection. Overall, these results show that the main virulence factor of P. atlantica for edible crabs is LPS either alone or in combination with other heat-stable factors.     

Tricyclic pyridones as functionally selective human GABAA alpha 2/3 receptor-ion channel ligands

A series of tricyclic pyridones has been evaluated as benzodiazepine site ligands with functional selectivity for the alpha(3) over the alpha(1) containing subtype of the human GABA(A) receptor ion channel. This investigation led to the identification of a high affinity, functionally selective, orally bioavailable benzodiazepine site ligand that demonstrated activity in rodent anxiolysis models and reduced sedation relative to diazepam.     

Differential expression of CYP102 in Bacillus megaterium by 17-beta-estradiol and 4-sec-butylphenol

Previously we have reported the induction of CYP102 in Bacillus megaterium by 17beta-estradiol (E2) and 4-sec-butylphenol (4-sBP). Electrophoretic mobility shift assay analyses demonstrated that E2 and 4-sBP both cause a dose-dependent disassociation of the Bm3R1 repressor protein from its binding site on the operator sequence of the CYP102 gene. Equimolar combinations of E2 and 4-sBP demonstrated additive induction of CYP102 compared to equivalent samples of E2 and 4-sBP added alone. Two gene constructs were used in this investigation. One construct designated BMC143 contained the entire regulatory region of CYP102. The other gene construct, designated BMA45, had the "Barbie box" sequence deleted. While the induction of CYP102 by 4-sBP was much higher in the BMC 143 construct, E2 induced CYP102 in both constructs to the same extent. This difference in induction of CYP102 by these two inducers indicates that they act at different sites, either on the Bm3R1 repressor protein or on positive regulatory sites, or that they act, in part, through different mechanisms.     

Relative placement of the mandibular fossa in great apes and humans

Several researchers have investigated, or commented on, the relative placement of the hominin mandibular fossa with regard to brain expansion and masticatory function. Two confounding factors are identified in this previous work. First, a number of different measurement techniques have been applied, confusing comparisons between studies. Second, the effects of squamous thickening due to temporal bone pneumatization are shown to influence measurements based relative to the ectocranial margin of the skull.To investigate the influence of these factors, a sample of adult human (n=12), chimpanzee (n=12), gorilla (n=15), and orang-utan (n=8) skulls from the Cleveland Museum of Natural History, University of Wisconsin Zoology Museum, and University of Wisconsin Anthropology collections, were CT scanned. Coronal scans were horizontally aligned and measured on a personal computer using ImageJ (NIH). To identify fossa placement, fossa breadth was measured as the projected distance in the coronal plane between the tip of the entoglenoid to lateral margin of the articular surface. A second distance, from the tip of the entoglenoid to a sagittal plane, tangent to the lateralmost margin of the endocranial surface was taken to indicate the extent of medial placement of the fossa. By eliminating the influence of pneumatization, these data unambiguously confirmed the medial placement of the human fossa and show all great apes as having a laterally placed fossa. Similar measurements on three fossil hominins, KNM-BC 1 (Homo sp. indet.), OH 5 and KNM-ER 23000 (Paranthropus boisei) demonstrate that, while all specimens demonstrate a broad fossa, only KNM-BC 1 is characterized by a relatively medial placement while the latter two display lateral placement.     

Thalassiolins A-C: new marine-derived inhibitors of HIV cDNA integrase

Human immunodeficiency virus (HIV) replication requires integration of viral cDNA into the host genome, a process mediated by the viral enzyme integrase. We describe a new series of HIV integrase inhibitors, thalassiolins A-C (1-3), isolated from the Caribbean sea grass Thalassia testudinum. The thalassiolins are distinguished from other flavones previously studied by the substitution of a sulfated beta-D-glucose at the 7-position, a substituent that imparts increased potency against integrase in biochemical assays. The most active of these molecules, thalassiolin A (1), displays in vitro inhibition of the integrase catalyzed strand transfer reaction (IC50=0.4 microM) and an antiviral IC50 of 30 microM. Molecular modeling studies indicate a favorable binding mode is probable at the catalytic core domain of HIV-1 integrase.