VHL and p53: tumor suppressors team up to prevent cancer

In a recent issue of Molecular Cell, Roe et al. (2006) report that the von Hippel-Lindau (VHL) protein is a positive regulator of p53, thus providing insight into the mechanisms by which VHL loss of function leads to cancer.     

Escape Behavior of the Formosan Subterranean Termite (Isoptera: Rhinotermitidae) in Response to Disturbance

Disturbances to monitors and baits have often been noted as a confounding factor for the success of termite baiting systems. We studied escape behavior of Coptotermes formosanus Shiraki to a food source disturbance in the laboratory. Four peripheral chambers connected to the central food chamber through tubes served as escape routes from which escape patterns, escape and return times and differences in soldier and worker responses were recorded. We used two sand conditions: moist and dry to test whether favorable versus unfavorable conditions change escape behavior. The post disturbance responses were video recorded for 1 h. C. formosanus quickly escaped from the central chamber when disturbed. The time taken to reach the maximum number of termites that escaped ranged from 20 s to 210 s followed by a gradual return to the disturbed chamber. The majority of the escapees returned to the disturbed area within a few minutes after evacuation in both dry and wet sand conditions. A significantly higher percentage of termites escaped in wet sand arenas (43%) than in the dry sand arenas (31%). Our experiments demonstrate that C. formosanus is highly unlikely to abandon bait stations for extensive periods of time as a result of mechanical disturbances regardless of habitat quality.     

Topological analysis of small leucine-rich repeat proteoglycan nyctalopin

Nyctalopin is a small leucine rich repeat proteoglycan (SLRP) whose function is critical for normal vision. The absence of nyctalopin results in the complete form of congenital stationary night blindness. Normally, glutamate released by photoreceptors binds to the metabotropic glutamate receptor type 6 (GRM6), which through a G-protein cascade closes the non-specific cation channel, TRPM1, on the dendritic tips of depolarizing bipolar cells (DBCs) in the retina. Nyctalopin has been shown to interact with TRPM1 and expression of TRPM1 on the dendritic tips of the DBCs is dependent on nyctalopin expression. In the current study, we used yeast two hybrid and biochemical approaches to investigate whether murine nyctalopin was membrane bound, and if so by what mechanism, and also whether the functional form was as a homodimer. Our results show that murine nyctalopin is anchored to the plasma membrane by a single transmembrane domain, such that the LRR domain is located in the extracellular space.     

Abbott Physicochemical Tiering (APT)--a unified approach to HTS triage

The selection of the highest quality chemical matter from high throughput screening (HTS) is the ultimate aim of any triage process. Typically there are many hundreds or thousands of hits capable of modulating a given biological target in HTS with a wide range of physicochemical properties that should be taken into consideration during triage. Given the multitude of physicochemical properties that define drug-like space, a system needs to be in place that allows for a rapid selection of chemical matter based on a prioritized range of these properties. With this goal in mind, we have developed a tool, coined Abbott Physicochemical Tiering (APT) that enables hit prioritization based on ranges of these important physicochemical properties. This tool is now used routinely at Abbott to help prioritize hits out of HTS during the triage process. Herein we describe how this tool was developed and validated using Abbott internal high throughput ADME data (HT-ADME).     

Differential survival of Ichthyophonus isolates indicates parasite adaptation to its host environment

In vitro viability of Ichthyophonus spp. spores in seawater and freshwater corresponded with the water type of the host from which the spores were isolated. Among Ichthyophonus spp. spores from both marine and freshwater fish hosts (Pacific herring, Clupea pallasii, and rainbow trout, Oncorhynchus mykiss, respectively), viability was significantly greater (P < 0.05) after incubation in seawater than in freshwater at all time points from 1 to 60 min after immersion; however, magnitude of the spore tolerances to water type differed with host origin. Ichthyophonus sp. adaptation to its host environment was indicated by greater seawater tolerance of spores from the marine host and greater freshwater tolerance of spores from the freshwater host. Prolonged aqueous survival of Ichthyophonus spp. spores in the absence of a host provides insight into routes of transmission, particularly among planktivorous fishes, and should be considered when designing strategies to dispose of infected fish carcasses and tissues.     

The normalization of gene expression data in melanoma: investigating the use of glyceraldehyde 3-phosphate dehydrogenase and 18S ribosomal RNA as internal reference genes for quantitative real-time PCR

We examined a panel of 26 melanoma and fibroblast samples (tissues and cultured cells) to evaluate the suitability of two commonly used housekeeping genes, glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and 18S ribosomal RNA (rRNA), for quantitative real-time PCR. Both genes showed significant variations within the individual cell line and tissue groups. Although no overall trends were observed in the expression of the 18S rRNA, GAPDH was up-regulated in melanoma tissue and cultured cells compared with the corresponding normal samples. In melanoma and fibroblast cell lines and tissues, absolute quantification appears to be more appropriate than normalizing messenger RNA (mRNA) expression via GAPDH or 18S rRNA housekeeping genes.     

Invasive species in China — an overview

China is a vast country with rich biodiversity, which makes China especially vulnerable to invasive species. It has a long history of introduction of non-native species, especially those with perceived beneficial impacts. Its rapid economic development, including an explosive growth in international trade and transportation, has increased the potential for new introductions. Currently, alien species are widespread in the country, occur in many ecosystems, represent most major taxonomic groups, and are introduced unintentionally as well as intentionally for cultivation. The paper lists various cases of invasive species which have caused significant threats or damages to local natural or artificial ecosystems, and indicates that two example industries (fresh water fisheries and lawn grasses) have brought or tend to bring in many invasive species and hence have caused or will cause changes and loss of biodiversity in local ecosystems. Based on these studies, it is suggested that China combat the problem through enhancing awareness, development of a database on invasive species, strengthening international co-operation, preparing case studies and introducing the necessary legislation, regulations and monitoring.     

Arginine kinase isoforms in the closest protozoan relative of metazoans

The genome of the choanoflagellate Monosiga brevicollis contains at least three genes for the phosphoryl transfer enzyme, arginine kinase (AK; EC 2.7.3.3). Bioinformatic analyses of the deduced amino acid sequences of the proteins coded for by two of these genes showed that one of these AKs is cytoplasmic (denoted AK1) while the other appears to have an N-terminal mitochondrial targeting peptide (denoted AK2). Cloning and expression of the cDNA for AK1 yielded considerable soluble AK activity. Three AK2 constructs were expressed - one corresponding to the full length protein and two corresponding to truncated versions in which the signal peptide had been deleted. Expression of the former construct yielded minimal soluble activity. In contrast, significant AK activity was found in both truncated constructs confirming the importance of removal of the targeting peptide for proper folding and catalytic activity. Both AK1 and AK2 are functional oligomers unlike typical AKs which are monomeric. A phylogenetic analysis showed that these choanoflagellate AKs group more closely with a supercluster consisting of cytoplasmic and mitochondrial CKs and invertebrate AKs that evolved secondarily from a CK-like ancestor. Reaction-diffusion constraints in choanoflagellates are likely mitigated by the presence of AK isoforms which facilitate energy transport in these highly polarized cells.