Comparative studies on the timing of reproduction and foetal number in six species of Australian conilurine rodents (Muridae: Hydromyinae)

The timing of reproduction and number of foetuses in the wild caught conilurine rodents Notomys mitchelli, N. alexis, Pseudomys albocinereus, P. hermannsburgensis, P. delicatulus and P. nanus was ascertained from museum preserved specimens. The two species from southern Australia ( N. mitchelli, P. albocinereus ) appeared to have a breeding season from late winter to early summer, whereas in those from the central region ( N. alexis and P. hermannsburgensis ) no such breeding season was evident. The little data available for the northern species, P. delicatulus , suggests at least reproduction during the winter. Foetal number was similar for the four species from southern and central Australia but tended to be slightly less in the two northern species. The significance of these findings in relation to the control of reproduction is briefly discussed.     

Sperm morphology in the Malagasy rodents (Muroidea: Nesomyinae)

The morphology of the spermatozoon of representative species of the subfamily Nesomyinae (Muroidea: Nesomyidae), a monophyletic group of rodents endemic to Madagascar, was examined by light and electron microscopy to determine the sperm head shape and tail length across the species. Marked interspecific differences were found to occur in both the form of the sperm head and length of the tail. The species that possess a sperm head with an apical hook, which largely contains acrosomal material, generally displayed longer sperm tails, and a species with a spatulate sperm head had the shortest tail. The association between sperm head shape and tail length mirrors that previously found in Eurasian and Australasian murine rodents. Thus, the repeated association between sperm head shape and tail length across these groups of muroid rodents clearly indicates a functional relationship between these two features. A comparison of sperm morphology of the nesomyines to that of related muroid rodents on the mainland of Africa suggests that the possession of an apical hook is the ancestral condition. J. Morphol., 2010. © 2010 Wiley‐Liss, Inc.     

The effect of temperature on the continuous ferrous-iron oxidation kinetics of a predominantly Leptospirillum ferrooxidans culture.

The ferrous-iron oxidation kinetics of a bacterial culture consisting predominantly of Leptospirillum ferrooxidans were studied in continuous-flow bioreactors. The bacterial culture was fed with a salts solution containing 12 g/L ferrous-iron, at dilution rates ranging from 0.01 to 0.06 l/h, and temperatures ranging from 30 to 40 degrees C, at a pH of 1.75. The growth rate, and the oxygen and ferrous-iron utilization rates of the bacteria, were monitored by means of off-gas analysis and redox-potential measurement. The degree-of-reduction balance was used to compare the theoretical and experimental values of r(CO(2)), -r(O(2)) and -r(Fe(+2)), and the correlation found to be good. The maximum bacterial yield on ferrous-iron and the maintenance coefficient on ferrous-iron, were determined using the Pirt equation. An increase in the temperature from 30 to 40 degrees C did not appear to have an effect on either the maximum yield or maintenance coefficient on ferrous-iron. The average maximum bacterial yield and maintenance coefficient on ferrous-iron were found to be 0.0059 mmol C/mmol Fe(2+) and 0.7970 mmol Fe(2+)/mmol C)/h, respectively. The maximum specific growth rate was found to be 0.077 l/h. The maximum specific ferrous-iron utilization rate increased from 8.65 to 13.58 mmol Fe(2+)/mmol C/h across the range from 30 to 40 degrees C, and could be described using the Arrhenius equation. The kinetic constant in bacterial ferrous-iron oxidation increased linearly with increasing temperature. The ferrous-iron kinetics could be accurately described in terms of the ferric/ferrous-iron ratio by means of a Michaelis-Menten-based model modified to account for the effect of temperature. A threshold ferrous-iron level, below which no further ferrous-iron utilization occurred, was found at a ferric/ferrous-iron ratio of about 2500. At an overall iron concentration of 12 g/L, this value corresponds to a threshold ferrous-iron concentration of 78.5 x10(-3) mM.     

Synthesis and evaluation of triazolones as checkpoint kinase 1 inhibitors

Checkpoint kinase 1 (Chk1, CHEK1) is a Ser/Thr protein kinase that plays a key role in mediating the cellular response to DNA-damage. Synthesis and evaluation of a previously described class of Chk1 inhibitors, triazoloquinolones/triazolones (TZs) is further described herein. Our investigation of structure-activity relationships led to the identification of potent inhibitors 14c, 14h and 16e. Key challenges included modulation of physicochemical properties and pharmacokinetic (PK) parameters to enable compound testing in a Chk1 specific hollow fiber pharmacodynamic model. In this model, 16e was shown to abrogate topotecan-induced cell cycle arrest in a dose dependent manner. The demonstrated activity of TZs in this model in combination with a chemotherapeutic agent as well as radiotherapy validates this series of Chk1 inhibitors. X-ray crystal structures (PDB code: 2YEX and 2YER) for an initial lead and an optimized analog are also presented.     

Glc7/protein phosphatase 1 regulatory subunits can oppose the Ipl1/aurora protein kinase by redistributing Glc7

Faithful chromosome segregation depends on the opposing activities of the budding yeast Glc7/PP1 protein phosphatase and Ipl1/Aurora protein kinase. We explored the relationship between Glc7 and Ipl1 and found that the phosphorylation of the Ipl1 substrate, Dam1, was altered by decreased Glc7 activity, whereas Ipl1 levels, localization, and kinase activity were not. These data strongly suggest that Glc7 ensures accurate chromosome segregation by dephosphorylating Ipl1 targets rather than regulating the Ipl1 kinase. To identify potential Glc7 and Ipl1 substrates, we isolated ipl1-321 dosage suppressors. Seven genes (SDS22, BUD14, GIP3, GIP4, SOL1, SOL2, and PEX31) encode newly identified ipl1 dosage suppressors, and all 10 suppressors encode proteins that physically interact with Glc7. The overexpression of the Gip3 and Gip4 suppressors altered Glc7 localization, indicating they are previously unidentified Glc7 regulatory subunits. In addition, the overexpression of Gip3 and Gip4 from the galactose promoter restored Dam1 phosphorylation in ipl1-321 mutant cells and caused wild-type cells to arrest in metaphase with unsegregated chromosomes, suggesting that Gip3 and Gip4 overexpression impairs Glc7's mitotic functions. We therefore propose that the overexpression of Glc7 regulatory subunits can titrate Glc7 away from relevant Ipl1 targets and thereby suppress ipl1-321 cells by restoring the balance of phosphatase/kinase activity.     

SAR and inhibitor complex structure determination of a novel class of potent and specific Aurora kinase inhibitors

A novel series of 5-aminopyrimidinyl quinazolines has been developed from anilino-quinazoline 1, which was identified in a high throughput screen for Aurora A. Introduction of the pyrimidine ring and optimisation of the substituents both on this ring and at the C7 position of the quinazoline led to the discovery of compounds that are highly specific Aurora kinase inhibitors. Co-crystallisation of one of these inhibitors with a fragment of Aurora A shows the importance of the benzamido group in achieving selectivity.     

Vaccination against Eimeria tenella infection using a fraction of E. tenella sporozoites selected by the capacity to activate T cells

At 8 days after a primary Eimeria tenella infection, a subset of T cells, of which the protective role is as yet unclear, circulates in the peripheral blood. In order to investigate this, the in vitro cellular responsiveness of these peripheral blood lymphocytes has been used as selection criterion to identify potentially protective E. tenella sporozoite antigens. The hydrophilic protein phase of purified E. tenella sporozoite homogenates obtained by Triton X-114 extraction was fractionated using preparative gel electrophoresis. Nine fractions, separated according to different molecular weight, were tested for their ability to stimulate T-cell responses. Both the proliferation of peripheral blood lymphocytes and the macrophage activating activity released in the culture supernatants were measured. On the basis of this responsiveness, four fractions were selected and used to vaccinate chickens. All vaccine preparations induced strong T-cell responses. One fraction immunised chickens against subsequent challenge infection, in that the caecal lesion scores were significantly lower as compared with that of the unvaccinated controls. This fraction contained hydrophilic polypeptides with a molecular mass that ranged from 26 to 30 kDa.