The Influence of Male Diet on Life History Traits of Female Mosquitoes

In the field, mosquitoes characteristically feed on sugars soon after emergence and intermittently during their adult lives. Sugar meals are commonly derived from plant nectar and homopteran honeydew, and without them, adults can only survive for a few days on larval reserves. In addition to sugar, females of most species rely on blood for the initiation and maintenance of egg development; thus their reproductive success depends to some extent on the availability of blood hosts. Males, on the other hand, feed exclusively on sugars. Consequently, their sexual maturation and reproductive success is largely dependent upon access to sugar sources. Plant nectar and homopteran honeydew are the two main sugar sources utilized by mosquitoes in the wild. Previous laboratory studies had shown that differences between nectar sources can affect the survivorship and biting frequency of disease vectoring mosquitoes. However, little is known on how sugar composition influence the reproductive processes in male mosquitoes. Male mosquitoes transfer accessory gland proteins and other hormones to their mates along with sperm during mating. In the female, these seminal fluid constituents exert their influence on reproductive genes that control ovulation and vitellogenesis. The present study tests the hypothesis that the mates of males consuming different sugar meals will exhibit varying levels of induction of vitellogenin (a gene which regulates the expression of egg yolk precursor proteins). Real-time quantitative RT-PCR was used to investigate how each sugar meal indirectly influences vitellogenin mRNA abundance in female Anopheles stephensi following mating. Results indicate that mates of nectar-fed males exhibit 2-fold greater change in vitellogenin expression than the mates of honeydew-fed males. However, this response did not occur in non-blood fed controls. These findings suggest that the stimulatory effect of mating on vitellogenesis in blood meal-reliant (i.e. anautogenous) mosquitoes may only be synergistic in nature. The present study also sought to compare the potential fitness costs of mating incurred by females that do not necessarily require a blood meal to initiate a reproductive cycle (i.e., exhibit autogeny). Females of the facultatively autogenous mosquito, Culex molestus were allowed to mate with males sustained on either nectar or honedyew. Mean lifetime fecundity and survivorship of females under the two different mating regimes were then recorded. Additionally, one-dimensional gel electrophoresis was used to verify the transfer of male accessory gland proteins to the sperm storage organs of females during mating.While there was no significant difference in survival between the test treatments, the mates of nectar-fed males produced 11% more eggs on average than mates of honeydew-fed males. However, additional data are needed to justify the extrapolation of these findings to natural settings. These findings prompt further investigation as the differences caused by diet variation in males may be reflected across other life history traits such as mating frequency and insemination capacity.

Characterization of the phosphorylation of thylakoid membrane proteins from cyanobacterium synechococcus sp. PCC 6301 in light state 1 and light state 2

The distribution of excitation energy between the two photosystems (PSII and PSI) of photosynthesis is regulated by the light state transition. Three models have been proposed for the mechanism of the state transition in phycobilisome (PBS) containing organisms, two involving protein phosphorylation. A procedure for the rapid isolation of thylakoid membranes and PBS fractions from the cyanobacterium Synechococcus m. PCC 6301 in light state 1 and light state 2 was developed. The phosphorylation of thylakoid and soluble proteins rapidly isolated from intact cells in state 1 and state 2 was investigated. 77 K fluorescence emission spectra revealed that rapidly isolated thylakoid membranes retained the excitation energy distribution characteristic of intact cells in state 1 and state 2. Phosphoproteins were identified by gel electrophoresis of both thylakoid membrane and phycobilisome fractions isolated from cells labelled with 32p orthophosphate. The results showed very close phosphoprotein patterns for either thylakoid membrane or PBS fractions in state 1 and state 2. These results do not support proposed models for the state transition which required phosphorylation of PBS or thylakoid membrane proteins.

Characterization and protein fingerprinting of Botrytis cinerea isolates /

Botrytis cinerea isolates collected from Niagara region were treated with different concentrations of the fiingicide, iprodione to test their sensitivity to this fungicide. These Botrytis cinerea isolates were divided into two groups according to their sensitivity to iprodione. Those isolates whose growth was inhibited by iprodione at concentrations < 2|i,g/nil were classified as sensitive isolates. Isolates that were able to show considerable growth at 2|j,g/ml iprodione were classified as resistant isolates. Resistant and sensitive isolates were compared for their morphological and growth characteristics, conidial germination, virulence on grape berries and protein banding profiles. The fungicide iprodione at a concentration of 2|xg/nil inhibited mycelial growth, sporulation and conidial germination of sensitive isolates but not those of resistant isolates. The inhibitory effect of the fungicide was greater on mycelial growth than on conidia germination of the sensitive isolates. Sensitive isolates produced no sclerotia whereas resistant isolates produced large number of sclerotia. The fungicide iprodione affected sclerotial production in the resistant isolates. The number of sclerotia was decreased by the increase of iprodione in the medium. Sporulation of resistant isolates was improved significantly in the presence of iprodione. The resistant isolates were as virulent as the sensitive isolates on grape berries. The sensitive and resistant isolates showed similar protein banding profiles in the absence of iprodione in polyacrylamide gel electrophoresis studies. Similar protein profiles were also observed when these isolates were grown in the presence of low iprodione concentration (0.5|ig/nil). However, in the presence of concentration (0.5|ig/nil). However, in the presence of iprodione at concentration of 5|Xg/nil, one protein band with approximate molecular weight of 83 KDa was present in the growing resistant isolates (and the controls) but was missing in the inhibited sensitive isolates.

Isolation and partial characterization of host cell wall surface glycoproteins: their involvement in agglutination, attachment and appressorium formation by piptocephalis virginiana

Cell surface proteins obtained by alkaline extraction from isolated cell walls of Mortierella pusilla and M. candelabrum, host and nonhost, respectively, to the mycoparasite, Piptocephalis virginiana, were tested for their ability to agglutinate mycoparasite spores. The host cell wall protein extract had a high agglutinating activity (788 a.u. mg- t ) as compared with the nonhost extract (21 a.li. mg- t ). SDS-polyacrylamide gel electrophoresis of the cell wall proteins revealed four protein bands, a, b, c, and d (Mr 117, 100, 85 and 64 kd, respectively) at the host surface, but not at the nonhost surface, except for the faint band c. Deletion of proteins b or c from the host cell wall protein extract significantly reduced its agglutinating activity. Proteins band c, obtained as purified preparations by a series of procedures, were shown to be two glycoproteins. Carbohydrate analysis by gas chromatography demonstrated that glucose and Nacetylglucosamine were the major carbohydrate components of the glycoproteins. It was further shown that the agglutinating activity of the pure preparation containing both band c was 500-850 times that of the single glycoproteins, suggesting the involvement of both glycoproteins in agglutination. The results suggest that the glycoproteins band c are the two subunits of agglutinin present at the host cell surface. The two glycoproteins band c purified from the host cell wall protein extract were further examined after various treatments for their possible role in agglutination, attachment and appressorium formation by the mycoparasite. Results obtained by agglutination and attachment tests showed: (1) the two glycoprotein-s are not only an agglutinin responsible for the mycoparasite spore agglutination, but may also serve as a receptor for the specific recognition, attachment and appressorium formation by the mycoparasite; (2) treatment of the rnycoparasite spores with various sugars revealed that arabinose, glucose and N-acetylglucosamine inhibited the agglutination and attachment activity of the glycoproteins, however, the relative percentage of appressorium formation was not affected by the above sugars; (3) the two glycoproteins are relatively stable with respect to their agglutinin and receptor functions. The present results suggest that the agglutination and attachment may be mediated directly by certain sugars present at the host and mycoparasite cell surfaces while the appressorlum formation may be the response of complementary combinations of both sugar and protein, the two parts of the glycoproteins at the interacting surfaces of two fungi.

An examination of transcriptional and translational regulation of the 70kDa heat shock proteins following amputation of the tail and forelimb in the newt Notophthalmus viridescens

Several stresses to tissues including hyperthermia, ischemia, mechanical trauma and heavy metals have been demonstrated to affect the regulation of a subset of the family of heat shock proteins of70kOa (hsp70). In several organisms following some of these traumas, the levels of hsp70 mRNA and proteins are dramatically upregulated. However, the effects of the stress on limb and tail amputation in the newt Notophthalmus viridescens, involving mechanical tissue damage, have not adequately been examined. In the present study, three techniques were utilized to quantitate the levels of hsp70 mRNA and protein in the tissues of the forelimbs and tails of newts during the early post-traumatic events following surgical resection of these:: appendages. These included quantitative Western blotting of proteins separated by both one and twodimensional SDS-polyacrylamide gel electrophoresis and quantitative Northern blot analysis of total RNA. In tissues of both the limb and tail one hour after amputation, there were no significant differences in the levels of hsp70 protein measured by one-dimensional SOSPAGE followed by Western blotting, when compared to the levels measured in the unamputated limb. A 30 minute heat shock at 35°C failed to elicit an increase in the levels of hsp70 protein in these tissues. Further analysis using the more sensitive 20 PAGE separation of stump tissue proteins revealed that at least some of the five hsp70 isoforms of the newt may be differentially regulated in limbs and tails in response to trauma. It appears also that amputation of the tail and limb tissues leads to slight 3 elevation in the levels of HSP70 mRNA when compared to those of their respective unstressed tissues.