Sexual behavior and factors affecting female reproduction in house and field crickets

The objective of this investigation was to clarify the adaptive significance of female sexual behaviours in the house cricket, Acheta domesticus, and the Texas field cricket, Gryllus integer. Experiments were focussed primarily on: nutritional factors affecting female reproductive success; the ontogeny of female sexual behaviours; female mating frequency and progeny production; and the pattern of sperm competition. Reproduction of singly mated female A. domesticus assigned to 3 nutritional regimes was compared . Females fed a vitamin and protein-enriched mouse chow, cannibalistic females, and starved females produced on the average, 513 , 200 and 68 offspring, respectively. Cannibals probably could not obtain the same amounts of essential nutrients as females fed mouse chow. Reabsorption of oocytes was likely the major factor contributing to the decreased reproduction of starved females. In addition, female !. domesticus fed mouse chow, but allowed constant access to males produced 11 times as many offspring than did females fed corn meal. Females fed corn meal probably could not absorb or synthesize enough dietary lipids, thus resulting in poor ovariole growth. Female !. domesticus first mate at an average adult age of 7 days, closely corresponding to when they first exhibit positive phonotaxis. Females mate repeatedly and often consume the externally attached spermatophore. In ~. domesticus, females allowed constant access to males produced significantly more offspring than did single maters. Similarly, doubly mated G. integer females produced more offspring than did single maters. This difference resulted largely from the failure of many single maters to reproduce. Remating by female crickets partly functions in offsetting the possibility of a failed initial mating. Nymph production increased significantly with the time the spermatophore was attached in singly mated ~. domesticus. Spermatophore consumption by the female was not affected by male guarding behaviour, and the interval between mating and eating of the spermatophore may often be shorter than the time required for maximum insemination. Some degree of sperm depletion in singly mated !. domesticus and G. integer may have occurred. The patterns of daily offspring production of singly and multiplymated females suggests that a factor provided by a male during mating stimulates female oviposition and/or egg production. Female crickets also might acquire nutrition from spermatophore consumption, a benefit that is augmented by female multiple mating. The electrophoretic examination of various allozymes in ~. integer did not permit determination of a pattern of sperm competition. However, the possibility of last male sperm predominance is related to male guarding behaviour.

Sexual selections in the northern fall field cricket, Gryllus pennsylvanicus: a manipulation of the adult sex ratio

The operational sex ratio has long been considered an important constraint on the structure of mating systems. The effects of an experimentally manipulated sex ratio on mating behavior and selection were investigated in a polygynous species, Gryllus pennsylvanicus, where the potential exists for spatial/temporal fluctuations in sex ratio of field populations. Four different sex ratios (males: females, 5:0, 5:2, 5:5, 5:10) were investigated. Observations were conducted in late summer over two field seasons, from 2400 h , to 1000 h EST. Several male characters thought to be associated with male reproduc.tive success were studied: calling duration, searching distance, weight, fighting behavior, courtship frequency, and mating success. Variance in male mating success was used as the indicator for the opportunity for sexual selection. Total selection was estimated as the univariate regression coefficient between relative fitness and the character of interest, while direct selection was estimated as standardized partial regression coefficients generated from a multiple regression of relative fitness on each character. The opportunity for sexual selection was highest at 5:2 and lowest at 5:10. The frequency of fighting behavior was highest at 5:2 and 5:5. Fighting ability (% wins) was determined to be an important correlate of male body weight. Direct selection for increased male body weight was detected at 5:2, while total selection for body weight was seen at 5:5. Selection on male body weight was not detected at 5: 10. Calling duration decreased as sex ratio became more female-biased. Total and direct selection were detected for increased calling at 5:2, only total selection for calling was seen at 5:5, whereas direct selection against calling was detected at 5: 10. Searching distance also decreased as sex ratio became more female-biased, however no form of selection was detected for searching at any of the sex ratios. Data are discussed in terms of sexual selection on male reproductive tactics, the mating system and maintenance of genetic variation in male reproductive behavior.

Shop-floor narratives : how six workers and a researcher describe learning activities

I am a part-time graduate student who works in industry. This study is my narrative about how six workers and I describe shop-floor learning activities, that is learning activities that occur where work is done, outside a classroom. Because this study is narrative inquiry, you wilileam about me, the narrator, more than you would in a more conventional study. This is a common approach in narrative inquiry and it is important because my intentions shape the way that I tell these six workers' stories. I developed a typology of learning activities by synthesizing various theoretical frameworks. This typology categorizes shop-floor learning activities into five types: onthe- job training, participative learning, educational advertising, incidental learning, and self-directed learning. Although learning can occur in each of these activities in isolation, it is often comprised of a mixture of these activities. The literature review contains a number of cases that have been developed from situations described in the literature. These cases are here to make the similarities and differences between the types of learning activities that they represent more understandable to the reader and to ground the typology in practice as well as in theory. The findings are presented as reader's theatre, a dramatic presentation of these workers' narratives. The workers tell us that learning involves "being shown," and if this is not done properly they "learn the hard way." I found that many of their best case lean1ing activities involved on-the-job training, participative learning, incidentalleaming, and self-directed learning. Worst case examples were typically lacking in properly designed and delivered participative learning activities and to a lesser degree lacking carefully planned and delivered on-the-job training activities. Included are two reflective chapters that describe two cases: Learning "Engels" (English), and Learning to Write. In these chapters you will read about how I came to see that my own shop-floor learning-learning to write this thesis-could be enhanced through participative learning activities. I came to see my thesis supervisor as not only my instructor who directed and judged my learning activities, but also as a more experienced researcher who was there to participate in this process with me and to help me begin to enter the research community. Shop-floor learning involves learners and educators participating in multistranded learning activities, which require an organizational factor of careful planning and delivery. As with learning activities, which can be multi-stranded, so too, there can be multiple orientations to learning on the shop floor. In our stories, you will see that these six workers and I didn't exhibit just one orientation to learning in our stories. Our stories demonstrate that we could be behaviorist and cognitivist and humanist and social learners and constructivist in our orientation to learning. Our stories show that learning is complex and involves multiple strands, orientations, and factors. Our stories show that learning narratives capture the essence of learning-the learners, the educators, the learning activities, the organizational factors, and the learning orientations. Learning narratives can help learners and educators make sense of shop-floor learning.

Sinister creativity: a phenomenological exploration of some of the experiences and perceptions of six lefthanded visual artists

Six lefthanded artist-educators were interviewed to attempt to discover any patterns t6 their perceptions and experiences. Artists have their own culture and priorities. According to the literature, lefthanded people appear more likely to suffer from dyslexia, allergies, asthma and other auto-immune diseases as well as machinery and equipment injuries. Patterns emerging suggested that lefthanded people indeed suffer more from dyslexia. More startling was the distinct possibility that many artists have traumatic childhood histories. This would commonly include negative school experiences, and for a significant number sexual assault, perceived or actual abandonment by parents, and/or consistently low selfesteem. The researcher discovered possible reasons why creative people frequently have problems at school, why they tend to be rebellious and anti-establishment oriented, how many of them perceive societal rules, and why they are more likely to be lefthanded. These characteristics all have significant implications for art school administrators.

Size regulation of double and half embryos in the mice musculus

Genetic chimeras made by aggregating early mouse embryos have many uses in developmental biology and have also provided insights into embryonic growth regulation. There is an indication that the embryo can regulate for an increase in size because although aggregation chimeras are twice as big as normal embryos when made, they are born of normal size. Upward regula..... tion of size reduced embryos is also possible. Half embryos made by the isolation or destruction of one of the blastomeres of a 2-cell embryo are also born of normal size. Little is known about the timing or the mechanism of this size regulation. In this study, the timing of size regulation in double and half embryos was clearly established by comparison of cell numbers derived from serial reconstruction of light microscope sections of control and experimental embryos. It was shown that size regulation in double embryos occurred around 6dl6h and in half embryos by 7dOh. Size regulation occurred in all tissues at the same time indicating a single control mechanism for the entire embryo. More detailed examination of the growth of double embryos revealed that size regulation occurred by alteration in cell cycle length~ No excessive cell death was found in double embryos compared to the controls and continuous labelling with [3H] thymidine showed no large non-dividing cell population in double embryos. However, a comparison of the mitotic index of double and control embryos after colcemid treatment, revealed a large difference between the two around 5dl6h to 6d16h. During this period, control embryos underwent a proliferative burst not shown by the double embryos. The mechanism for cell cycle control is not clear; it may be intrinsic to the embryo or determined by the uterine environment. Evidence was found suggesting that differentiation in the postimplantation embryo was cell number dependent. The timing of differentiative events was examined in half, double and control embryos. Proamnion formation, which occurs prior to size regulation, occurs at the same cell number but at different times in the three groups of embryos. However mesoderm which appears after size regulation was seen at the same time in all grollps of embryos.

Sol-gel routes to supported Friedel-Crafts alkylation catalysts

Aluminosilicate catalysts containing supported ZnCl2 and metal fluoride salts have been prepared using a sol-gel based route, tested and characterized. The activities of these ZnCl2 + metal fluoride catalysts, while greater than "Clayzic" (ZnCI2 supported on montmorillonite KIO) are not as good as supported ZnCl2 only supported on aluminosilicate. Alumina supports have also been prepared via a sol-gel route using various chemical additives to generate a mesoporous structure, loaded with ZnCl2 and tested for activity. The activities for these alumina-supported catalysts are also significantly higher than that of "Clayzic", an effective Friedel-Crafts catalyst. Characterizations of these two types of catalysts were done by magic angle spinning (MAS) NMR, diffuse reflectance infrared (DRIFT) spectroscopy and additionally for the alumina nitrogen adsorption studies were done. Supported aluminum trichloride was also investigated as an alternative to the traditional use of aluminum trichloride.

Solid state NMR chemical shifts as an alternative to diffraction data in the determination of SIC polytypic structures

Silicon carbide, which has many polytypic modifications of a very simple and very symmetric structure, is an excellent model system for exploring, the relationship between chemical shift, long-range dipolar shielding, and crystal structure in network solids. A simple McConnell equation treatment of bond anisotropy effects in a poly type predicts chemical shifts for silicon and carbon sites which agree well with the experiment, provided that contributions from bonds up to 100 A are included in the calculation. The calculated chemical shifts depend on three factors: the layer stacking sequence, electrical centre of gravity, and the spacings between silicon and carbon layers. The assignment of peaks to lattice sites is proved possible for three polytypes (6H, 15R, and 3C). The fact that the calculated chemical shifts are very sensitive to layer spacings provides us a potential way to detennine and refine a crystal structure. In this work, the layer spacings of 6H SiC have been calculated and are within X-ray standard deviations. Under this premise, the layer spacings of 15R have been detennined. 29Si and 13C single crystal nmr studies of 6H SiC polytype indicate that all silicons and carbons are magnetically anisotropic. The relationship between a magnetic shielding tensor component and layer spacings has been derived. The comparisons between experimental and semi-empirical chemical shielding tensor components indicate that the paramagnetic shielding of silicon should be included in the single crystal chemical shift calculation.

Solute effects on the production and decay of primary species in the flash photolysis of indole

Maximum production rates ofs and decay kinetics for the hydrated electron, the indolyl neutral radical and the indole triplet state have been obtained in the microsecond, broadband (X > 260 nm) flash photolysis of helium-saturated, neutral aqueous solutions of indole, in the absence and in the presence of the solutes NaBr, BaCl2*2H20 and CdSCV Fluorescence spectra and fluorescence lifetimes have also been obtained in the absence and in the presence of the above solutes, The hydrated electron is produced monophotonically and biphotonically at an apparent maximum rate which is increased by BaCl2*2H20 and decreased by NaBr and CdSOif. The neutral indolyl radical may be produced monophotonically and biphotonically or strictly monophotonically at an apparent maximum rate which is increased by NaBr and CdSO^ and is unaffected by BaCl2*2H20. The indole triplet state is produced monophotonically at a maximum rate which is increased by all solutes. The hydrated electron decays by pseudo first order processes, the neutral indolyl radical decays by second order recombination and the indole triplet state decays by combined first and second order processes. Hydrated electrons are shown to react with H , H2O, indole, Na and Cd"*""1"". No evidence has been found for the reaction of hydrated electrons with Ba . The specific rate of second order neutral indolyl radical recombination is unaffected by NaBr and BaCl2*2H20, and is increased by CdSO^. Specific rates for both first and second order triplet state decay processes are increased by all solutes. While NaBr greatly reduced the fluorescence lifetime and emission band intensity, BaCl2*2H20 and CdSO^ had no effect on these parameters. It is suggested that in solute-free solutions and in those containing BaCl2*2H20 and CdSO^, direct excitation occurs to CTTS states as well as to first excited singlet states. It is further suggested that in solutions containing NaBr, direct excitation to first excited singlet states predominates. This difference serves to explain increased indole triplet state production (by ISC from CTTS states) and unchanged fluorescence lifetimes and emission band intensities in the presence of BaCl2*2H20 and CdSOt^., and increased indole triplet state production (by ISC from S^ states) and decreased fluorescence lifetime and emission band intensity in the presence of NaBr. Evidence is presented for (a) very rapid (tx ^ 1 us) processes involving reactions of the hydrated electron with Na and Cd which compete with the reformation of indole by hydrated electron-indole radical cation recombination, and (b) first and second order indole triplet decay processes involving the conversion of first excited triplet states to vibrationally excited ground singlet states.

Some aspects of the chemistry of Reissert compounds / |nDurga Prasad Aysola. -- 260 St. Catharines [Ont. : s. n.],

1-(0- and m-Ohlorobenzoyl)isoquinolines have been synthesized by two routes involving Reissert compounds. One route involves condensation of 2-benzoyl-l,2-dihydroisoquinaldonitrile with the appropriate chlorobenzaldehyde and the second involves rearrangement of the appropriate Z-(chlorobenzoyl)-l,Z-dihydroisoquinaldonitrile under basic conditions. The action of potassamide in anhydrous liquid ammonia on both ketones gave unexpectedly N-(l-isoquinolyl)benzamide (67) as the major product and the use of dibenzo-18-crown-6-ether 98% substantially improved the yd..e.ld in the case of l-chloroketone. This amide (67) exhibits unusual hydrogen bonding. 1-(o-chlorobenzoyl)-6,7-dimethoxyisoquinoline (79) was prepared in very s,amll quantities by the route involving condensation of 2-benzoyll, Z-dihydro-6,7-dimethoxyisoquinaldonitrile with o-chlorobenzaldehyde. The poor yields are due to the instability of the anion of 2-benzoyl1, Z-dihydro-6,7-dimethoxyisoquinaldonitrile. Attempted preparation of the ketone (79) by rearrangement of 2-(o-chlorobenzoyl)-l,2-dihydro6,7- dimethoxyisoquinaldonitrile under basic conditions yielded the start~ng material (Reissert compound) and 6,7-dimethoxyisoquinoline. The action of potassamide in anhydrous liquid ammonia on l-(o-bromo-4,5-dimethoxybenzoyl)isoquinoline (85), which was prepared by the route involving the condensation of 2-benzoyl-l,4-dihydroisoquinaldonitrile with o-bromo-4,5-dimethoxybenzaldehyde, gave two products, which have not yet been identified. The ketone (85) and its precursors are interest~ng in that their 20 eV and 70 eV mass spectra do not show molecular ions.