Procedure and Analysis of a Useful Method in Determining Mycelial Dry Weights from Agar Plates

The evaluation of growth by dry weight determination of fungus mycelium for agar plates was examined. The data obtained were statistically analyzed. This method was shown to be sufficiently accurate to be used as an investigative tool.     

Externally attached radio transmitters do not affect the parental care behaviour of rock bass

Turning, pectoral fin and caudal fin rates and time spent on the nest of male rock bass Ambloplites rupestris , engaged in parental care, were not affected after the attachment of external radio transmitters. Reproductive success was similar between treatment and control fish. Micro external radio transmitters can be used on small fishes for studying parental care duration and post-care movement without altering their behaviour.     

Interactions between two catalytically distinct MCM subgroups are essential for coordinated ATP hydrolysis and DNA replication.

The six MCM (minichromosome maintenance) proteins are essential DNA replication factors that each contain a putative ATP binding motif and together form a heterohexameric complex. We show that these motifs are required for viability in vivo and coordinated ATP hydrolysis in vitro. Mutational analysis discriminates between two functionally distinct MCM protein subgroups: Mcm4p, 6p, and 7p contribute canonical ATP binding motifs essential for catalysis, whereas the related motifs in Mcm2p, 3p, and 5p serve a regulatory function. Reconstitution experiments indicate that specific functional interactions between these two subgroups are required for robust ATP hydrolysis. Our observations show parallels between the MCM complex and the F1-ATPase, and we discuss how ATP hydrolysis by the MCM complex might be coupled to DNA strand separation.     

An antigenic HIV-1 peptide sequence engineered into the surface structure of transferrin does not elicit an antibody response.

One novel approach for the biological delivery of peptide drugs is to incorporate the sequence of the peptide into the structure of a natural transport protein such as human serum transferrin (HST). However, a potential drawback is that the HST may increase the immunoreactivity of the peptide, in the same way that carrier proteins can be used to generate highly immunogenic peptide hapten conjugates. In this study we have generated a recombinant HST carrier protein that contains a peptide substrate of HIV-1 protease (VSQNYPIVL). The protein retained native HST function, and the peptide was surface exposed since it was immunoreactive in native dot blots, and was cleaved by HIV-1 protease. Immunisation of rabbits with the recombinant protein elicited only a very poor anti-peptide immune response. In contrast, strong anti-peptide immune responses were raised against both the peptide alone, and a chemical conjugate of the peptide with HST. These data demonstrate that it is possible to attenuate the immune response normally directed against an immunogenic peptide sequence by engineering into a surface exposed loop of HST. These findings may have an important impact on the future design of peptide delivery systems.     

Sexually dimorphic expression of myosin heavy chains in the adult mouse masseter.

Little is known regarding the role of androgenic hormones in the maintenance of myosin heavy chain (MHC) composition of rodent masticatory muscles. Because the masseter is the principal jaw closer in rodents, we felt it was important to characterize the influence of androgenic hormones on the MHC composition of the masseter. To determine the extent of sexual dimorphism in the phenotype of masseter muscle fibers of adult (10-mo-old) C57 mice, we stained tissue sections with antibodies specific to type IIa and IIb MHC isoforms. Females contain twice as many fibers containing the IIa MHC as males, and males contain twice as many fibers containing the IIb MHC as females. There is a modest amount of regionalization of MHC phenotypes in the mouse masseter. The rostral portions of the masseter are composed mostly of type IIa fibers, whereas the midsuperficial and caudal regions contain mostly type IIb fibers. Using immunoblots, we showed that castration results in an increase in the expression of type IIa MHC fibers in males. Ovariectomy has no effect on the fiber type composition in females. We conclude that testosterone plays a role in the maintenance of MHC expression in the adult male mouse masseter.     

Floral colour diversity in plant communities,bee colour space and a null model

Evolutionary biologists have long hypothesized that the diversity of flower colours we see is in part a strategy to promote memorization by pollinators, pollinator constancy, and therefore, a directed and efficient pollen transfer between plants. However, this hypothesis has never been tested against a biologically realistic null model, nor were colours assessed in the way pollinators see them. Our intent here is to fill these gaps. Throughout one year, we sampled floral species compositions at five ecologically distinct sites near Berlin, Germany. Bee-subjective colours were quantified for all 168 species. A model of colour vision was used to predict how similar the colours of sympatric and simultaneously blooming flowers were for bees. We then compared flower colour differences in the real habitats with those of random plant communities. We did not find pronounced deviations from chance when we considered common plants. When we examined rare plants, however, we found significant divergence in two of the five plant communities. At one site, similarly coloured species were found to be more frequent than expected, and at the other two locations, flower colours were indistinguishable from a random distribution. These results fit theoretical considerations that rare plants are under stronger selective pressure to secure pollination than common plants. Our study illustrates the power of linking such distinct biological traditions as community ecology and the neuroethology of bee vision.