Induction of the 47 kDa platelet substrate of protein kinase C during differentiation of HL-60 cells.

Immunoblot analysis showed that the 47 kDa platelet substrate of protein kinase C (P47) was expressed at low levels in undifferentiated HL-60 leukaemia cells. Treatment of these cells with dimethyl sulphoxide, 1 alpha,25-dihydroxycholecalciferol or retinoic acid caused progressive increases in P47 content. Retinoic acid (1 microM) elicited the largest response, a 4-fold increase in P47 protein after 7 days that was accompanied by an increase in translatable P47 mRNA. The induction of P47 by retinoic acid preceded cessation of cell proliferation and development of the capacity to reduce Nitro Blue Tetrazolium, indicating that its expression is an early event in the myeloid differentiation of HL-60 cells.     

The pharmacological characterization of 5-HT3 receptor binding sites in rabbit ileum: Comparison with those in rat ileum and rat brain

We have further characterized the 5-HT₃ receptors in rat and rabbit tissues by evaluating the binding of the 5-HT₃ receptor ligand, [³H]GR67330 to homogenates of rabbit ileum, rat ileum and rat brain (entorhinal cortex). In each tissue specific [³H]GR67330 binding represented a single saturable, high affinity site (K_d = 0.14, 0.18, 0.076 nM in rabbit ileum, rat ileum and rat brain respectively). The densities of sites present in rabbit and rat ileum were similar to that present in rat brain (B_max = 63, 47, 72 fmol/mg protein in rabbit ileum, rat ileum and rat brain respectively).

In each tissue, 5-HT₃ receptor agonists and antagonists potently competed for [³H]GR67330 binding. Derived inhibition constants were similar in rat ileum and brain. However marked differences in IC₅₀s were apparent for rabbit ileum compared with rat brain or ileum. These were most apparent with agonists. Thus, mCPBG [1-(meta-chlorophenylbiguanide)], phenylbiguanide, 5-HT and 2-methyl 5-HT were at least 5 times less potent to inhibit [³H]GR67330 binding in rabbit ileum than rat brain. The most pronounced differences were evident with phenylbiguanide and mCPBG which were 70 and 300 times less potent in the rabbit ileum respectively compared with the rat tissues. These differences were unlikely to be due to depletion effects because tissue combination experiments (rabbit ileum and rat brain) yielded biphasic inhibition curves for phenylbiguanide with affinities for each component similar to those in the individual tissues. Antagonist affinities also varied between the rabbit and rat tissues, although less markedly. Amongst the antagonists, the most marked differences were apparent with SDZ 206–830 and quipazine each being 10 times less potent to inhibit binding to rabbit than rat tissue.

Hill coefficients for inhibition of binding varied with tissue. In rat brain, as previously described for [³H]GR67330, Hill coefficients for agonist (and quipazine) inhibition of binding were greater than unity. This was less marked in rat and rabbit ileum tissues.

The present studies provide further evidence for species variation in 5-HT₃ receptors.     

Bridging the Gap Between Salmon Spawner Abundance and Marine Nutrient Assimilation by Juvenile Salmon: Seasonal Cycles and Landscape Effects at the Watershed Scale

Ecosystems - Anadromous Pacific salmon are semelparous, and resource subsidies from spawning adults (marine-derived nutrients, or MDN) benefit juvenile salmonids rearing in freshwater. However, it...     

Signal and preference divergence among populations of the non‐endemic basal Lake Malawi cichlid fish Astatotilapia calliptera (Perciformes: Cichlidae)

In Lake Malawi and Lake Victoria, cichlid fishes have diversified into hundreds of species, many reproductively isolated by mate choice. Territorial males tend to be more aggressive to similar‐coloured males, facilitating coexistence of divergent colour morphs or species. Behavioural mate choice and aggression biases of species and allopatric populations of specialized rocky shore cichlids are influenced by divergent signals such as male colour. Believed to be basal to the Lake Malawi haplochromine radiation, and inhabiting shallow weedy areas of the lake and neighbouring water bodies, Astatotilapia calliptera also shows allopatric variation in colour. Here, it is demonstrated that such signal divergence is associated with tendencies of females to mate with males of their own population and also for males to preferentially attack males of their own population, indicating that preference divergence related to signal divergence in allopatry may have operated throughout the adaptive radiation of the Malawian cichlids. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110 , 180–188.     

Structure-templated predictions of novel protein interactions from sequence information

The multitude of functions performed in the cell are largely controlled by a set of carefully orchestrated protein interactions often facilitated by specific binding of conserved domains in the interacting proteins. Interacting domains commonly exhibit distinct binding specificity to short and conserved recognition peptides called binding profiles. Although many conserved domains are known in nature, only a few have well-characterized binding profiles. Here, we describe a novel predictive method known as domain–motif interactions from structural topology (D-MIST) for elucidating the binding profiles of interacting domains. A set of domains and their corresponding binding profiles were derived from extant protein structures and protein interaction data and then used to predict novel protein interactions in yeast. A number of the predicted interactions were verified experimentally, including new interactions of the mitotic exit network, RNA polymerases, nucleotide metabolism enzymes, and the chaperone complex. These results demonstrate that new protein interactions can be predicted exclusively from sequence information.     

Widespread colonisation of Tanzanian catchments by introduced Oreochromis tilapia fishes: the legacy from decades of deliberate introduction

From the 1950s onwards, programmes to promote aquaculture and improve capture fisheries in East Africa have relied heavily on the promise held by introduced species. In Tanzania these introductions have been poorly documented. Here we report the findings of surveys of inland water bodies across Tanzania between 2011 and 2017 that clarify distributions of tilapiine cichlids of the genus Oreochromis. We identified Oreochromis from 123 sampling locations, including 14 taxa restricted to their native range and three species that have established populations beyond their native range. Of these three species, the only exotic species found was blue-spotted tilapia (Oreochromis leucostictus), while Nile tilapia (Oreochromis niloticus) and Singida tilapia (Oreochromis esculentus), which are both naturally found within the country of Tanzania, have been translocated beyond their native range. Using our records, we developed models of suitable habitat for the introduced species based on recent (1960–1990) and projected (2050, 2070) East African climate. These models indicated that presence of suitable habitat for these introduced species will persist and potentially expand across the region. The clarification of distributions provided here can help inform the monitoring and management of biodiversity, and inform policy related to the future role of introduced species in fisheries and aquaculture.