Winter food provisioning reduces future breeding performance in a wild bird.

Supplementation of food to wild birds occurs on an enormous scale worldwide, and is often cited as an exemplar of beneficial human-wildlife interaction. Recently it has been speculated that winter feeding could have negative consequences for future reproduction, for example by enabling low quality individuals to recruit into breeding populations. However, evidence that winter feeding has deleterious impacts on reproductive success is lacking. Here, in a landscape-scale study of blue tits (Cyanistes caeruleus) across multiple years, we show that winter food supplementation reduced breeding performance the following spring. Compared to unfed populations, winter-fed birds produced offspring that weighed less, were smaller, and had lower survival. This impairment was observed in parents that had received fat only, or in combination with vitamin E, suggesting some generality in the mechanism by which supplementary feeding affected reproduction. Our results highlight the potential for deleterious population-level consequences of winter food supplementation on wild birds.

RNA interference in the light brown apple moth, Epiphyas postvittana (Walker) induced by double-stranded RNA feeding.

RNA interference (RNAi) or gene silencing is typically induced in insects by the injection of double-stranded RNAs (dsRNAs), short interfering RNAs, or through the use of hairpin constructs in transgenic insects. Here we demonstrate in the horticultural pest, Epiphyas postvittana (Lepidoptera: Tortricidae), that RNAi can be triggered by oral delivery of dsRNA to larvae. Transcript levels of a larval gut carboxylesterase gene (EposCXE1) were reduced to less than half that of controls within 2 days of being fed EposCXE1 dsRNA. Transcript levels of the pheromone binding protein gene (EposPBP1) were reduced in adult antennae by feeding larvae EposPBP1 dsRNA. Knockdown of EposPBP1 transcripts was observed for the first 2 days after adult eclosion but recovered to wild-type levels at 4 days posteclosion. The potential mechanisms involved in the initiation, movement and amplification of the silencing signal are discussed.

Molecular Identification of a Sexual Interloper: The Pear Pathogen, Venturia pirina, has Sex on Apple.

ABSTRACT Venturia pirina (the pear scab pathogen) and V. inaequalis (the apple scab pathogen) were detected as ascospores discharged from apple leaf litter in New Zealand (spring 1998). Pseudothecia of both species were located on dead apple leaves; however, only those of V. inaequalis were associated with scab lesions. V. pirina was identified by rDNA sequence analyses, because morphological characters could not distinguish this fungus from V. asperata (a rare saprophyte on apple) and other Venturia spp. pathogenic on rosaceous fruit trees. Species-specific polymerase chain reaction primers designed to the 18S end of the internal transcribed spacer 1 region differentiated Venturia fruit tree pathogens reliably. V. pirina field isolates were pathogenic on pear, but only weak saprophytes on apple. In rare instances, when appressoria of V. pirina appeared to penetrate the cuticle of apple leaves, epidermal cells responded with a localized hypersensitive response (HR). To our knowledge, this is the first report of induction of HR-like events by V. pirina on its nonhost, apple, and also the first record of sexual reproduction of V. pirina on apple. It is assumed that V. pirina pseudothecia formed from saprophytic lesions in senescing apple leaves when active defense mechanisms such as HR were no longer induced.

From nursing outposts to contemporary midwifery in 20th century Canada.

Knowledge of the history of one's profession is always related to the informed practice of the profession and can aid midwifery in its expansion and recognition. Understanding the long and diverse history of Canadian midwifery expands the appreciation by midwives in the United States of midwifery north of our border, which, although newly regulated, has much experience to share. This article documents the evolution of midwifery in Canada during the 20th century. Government-sanctioned midwifery prior to 1991, the year when Ontario passed legislation to regulate midwifery for the first time in modern Canadian history, was limited to isolated, usually northern, frontier and outpost regions of Canada, but the providers who practiced it were well-educated and important figures in the broader history of midwifery.

Muscarinic receptor subtypes in the lateral geniculate nucleus: a light and electron microscopic analysis.

Neural activity in the dorsal lateral geniculate nucleus of the thalamus (DLG) is modulated by an ascending cholinergic projection from the brainstem. The purpose of this study was to identify and localize specific muscarinic receptors for acetylcholine in the DLG. Receptors were identified in rat and cat tissue by means of antibodies to muscarinic receptor subtypes, ml-m4. Brain sections were processed immunohistochemically and examined with light and electron microscopy. Rat DLG stained positively with antibodies to the m1, m2,and m3 receptor subtypes but not with antibodies to the m4 receptor subtype. The m1 and m3 antibodies appeared to label somata and dendrites of thalamocortical cells. The m1 immunostaining was pale, whereas m3-positive neurons exhibited denser labeling with focal concentrations of staining. Strong immunoreactivity to the m2 antibody was widespread in dendrites and somata of cells resembling geniculate interneurons. Most m2-positive synaptic contacts were classified as F2-type terminals, which are the presynaptic dendrites of interneurons. The thalamic reticular nucleus also exhibited robust m2 immunostaining. Cat DLG exhibited immunoreactivity to the m2 and m3 antibodies. The entire DLG stained darkly for the m2 receptor subtype, except for patchy label in the medial interlaminar nucleus and the ventralmost C laminae. The staining for m3 was lighter and was distributed more homogeneously across the DLG. The perigeniculate nucleus also was immunoreactive to the m2 and m3 subtype-specific antibodies. Immunoreactivity in cat to the m1 or m4 receptor antibodies was undetectable. These data provide anatomical evidence for specific muscarinic-mediated actions of acetylcholine on DLG thalamocortical cells and thalamic interneurons.

Effect of disruption of a cutinase gene (cutA) on virulence and tissue specificity of Fusarium solani f. sp. cucurbitae race 2 toward Cucurbita maxima and C. moschata.

A 3.9-kb genomic DNA fragment from the cucurbit pathogen Fusarium solani f. sp. cucurbitae race 2 was cloned. Sequence analysis revealed an open reading frame of 690 nucleotides interrupted by a single 51-bp intron. The nucleotide and predicted amino acid sequences showed 92 and 98% identity, respectively, to those of the cutA gene of the pea pathogen F. solani f. sp. pisi. A gene replacement vector was constructed and used to generate cutA- mutants that were detected with a polymerase chain reaction (PCR) assay. Seventy-one cutA- mutants were identified among the 416 transformants screened. Vector integration was assessed by Southern analysis in 23 of these mutants. PCR and Southern analysis data showed the level of homologous integration was 14%. Disruption of the cutA locus in mutants was confirmed by RNA gel blot hybridization. Neither virulence on Cucurbita maxima cv. Delica at any of six different inoculum concentrations, nor pathogenicity on intact fruit of four different species or cultivars of cucurbit or hypocotyl tissue of C. maxima cv. Crown, was found to be affected by disruption of the cutA gene.

NorA plasmid resistance to fluoroquinolones: role of copy number and norA frameshift mutations.

Staphylococcus aureus NorA protein is a transmembrane multidrug efflux pump that confers low-level resistance to hydrophilic fluoroquinolones. The norA gene promoter is active in Escherichia coli HB101. We have examined the genetic basis of norA-mediated resistance in E. coli by introducing a wild-type norA gene into HB101 in plasmid pCL1921, pBR322, or pUC18 exhibiting copy numbers that spanned a 22-fold range. Increased ciprofloxacin resistance correlated with norA transcript levels seen by Northern (RNA) analysis. Thus, contrary to some reports, a wild-type norA gene confers fluoroquinolone resistance in E. coli in a copy-number-dependent fashion and does not require mutational activation. Interestingly, a multicopy pUC19norA derivative gave transformants exhibiting a range of resistance phenotypes. The norA gene of one transformant carried a single base deletion (ATACAAT to AACAAT; the deleted base is underlined) in the putative--10 Pribnow box resulting in a promoter down-regulatory mutation; a second plasmid had acquired a frameshift producing a null mutation at codon 112. These mutations override the dual resistance-growth-inhibitory phenotype of high-copy-number norA plasmids. The results have implications for using the standard E. coli HB101 system to assess NorA function and potentially for plasmid-borne transmission of norA-mediated drug resistance.

Inheritance of chromosomal length polymorphisms in the ascomycete Leptosphaeria maculans.

Pulsed field gel electrophoresis experiments show that chromosomal length polymorphisms are produced during meiosis in the ascomycetous plant pathogen Leptosphaeria maculans. Homologues in tetrads of L. maculans were identified on the basis of their binding to chromosome-specific probes that included beta-tubulin, nitrate reductase, 18S ribosomal DNA and two Random Amplified Polymorphic DNA (RAPD) markers. Changes in size of homologues were followed during meiosis. Significant karyotype variation was evident due to the random assortment of parental homologues of different sizes. In most cases, the progeny had the same-sized homologues as the parents; however, in some instances novel-sized homologues were detected that varied in size from those of the parents by up to 50 kb. Our results are consistent with the hypothesis that these novel chromosomal length polymorphisms are produced by reciprocal recombination between parental homologous chromosomes of unequal sizes.

Bonding soft reline materials to base metals.

PURPOSE: In the past it has been difficult to treat soft tissue changes occurring beneath metal frameworks of removable partial dentures or complete dentures using soft reline materials. The main difficulty has been in getting the resilient materials to adhere to the metal. This research investigates the use of microabrading with and without a universal resin bonding system in achieving a clinically useful bond between two soft reline materials and a commonly used base-metal alloy. MATERIALS AND METHODS: 120 disks, 1 inch in diameter, were cast in Ticonium (CPM Industries, Albany, NY). The surface of the disks was finished to a high polish and then evenly microabraded. Four test groups of 15 pairs of disks were established, with two groups receiving Coe-Soft (Coe Laboratories, Chicago, IL) and two groups receiving Soft Oryl (Teledyne Getz, Elk Grove Village, IL). One group of each reline material had the microabraded surfaces on each disk treated with All Bond 2. Then, 1.2 mm of reline material was placed between each set of disks and allowed to cure. The disks were placed on an Instron machine and a tensile force was applied until bond failure occurred. RESULTS: All four groups showed significant bond strengths, with the Soft Oryl groups showing statistically significant higher bond strengths. In both reline material groupings, the groups with only microabrading showed slightly higher bond strengths. CONCLUSIONS: Soft reline materials can be made to adhere to base-metal alloys used in removable prosthodontics with clinically acceptable strengths using microabrading with or without the use of a resin bonding system.

Practical infection control in dental laboratories.

Regardless of the dental laboratory infection control methods that are used, excellent communication and cooperation between laboratory staff members and clients must be maintained. The safety of patients is assured only through confidence that dentists and dental technicians use the proper procedures correctly. Whenever a question exists about possible contamination of an item that is brought into the laboratory, the item should be treated as contaminated until processed by prescribed methods.

Development of corticotectal synaptic terminals in the cat: a quantitative electron microscopic analysis.

We studied the development of corticotectal synaptic terminal boutons and synapses by making injections of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) into area 17 of visual cortex in kittens ranging from newborn to 12 weeks of age and in adults. The location and extent of the injection site, and labeled corticotectal axon terminals in the superficial layers of the superior colliculus were demonstrated histochemically with the cobalt-glucose oxidase diaminobenzidine reaction. During the first 2 weeks after birth, the majority of labeled profiles resembled axonal growth cones, or structures intermediate in morphology between growth cones and synaptic terminals, while very few corticotectal axon terminals forming well-defined synaptic contacts were observed. Labeled synaptic terminals in kittens at 1 and 2 weeks of age were small, contained very few synaptic vesicles, which were usually restricted to the contact zone, and exhibited few mitochondria. By 4 and 6 weeks after birth, a well-developed population of synaptic terminals was established; however, growth cones and intermediate profiles were still numerous. At 8 weeks of age synaptic terminals were morphologically mature, and growth cone-like profiles were no longer observed. To study quantitative changes in synapse development we used the disector method to obtain unbiased estimates of the density and number of corticotectal synaptic terminals and synapses; both the density and number of terminals and synapses increased steadily throughout postnatal development. These results suggest that the corticotectal projection develops by the progressive elaboration of synapses, as opposed to synapse overproduction and subsequent elimination.

Practical denture disinfection.

Dental laboratory personel are at risk of contracting infections from dental prostheses that have not been properly disinfected. A 4% chlorhexidine scrub for 15 seconds followed by a 3-minute contact time with a chlorine dioxide solution was effective in disinfecting contaminated dentures. Chair-side disinfection of dental prostheses before laboratory procedures is the key to keeping microbial contamination out of the dental laboratory.

Major chromosomal length polymorphisms are evident after meiosis in the phytopathogenic fungus Leptosphaeria maculans.

Chromosomal DNA of Australian field-isolates of the phytopathogenic ascomycete Leptosphaeria maculans was resolved by pulsed-field gel electrophoresis. All isolates examined had highly variable karyotypes. Ascospores (sexual spores) derived from single pseudothecia (sexual fruiting bodies) isolated from Brassica napus (oilseed rape) stubble were analyzed. In two tetrads four distinct karyotypes were observed, with only one chromosomal DNA band in common to all the members of each tetrad. Although isolates had highly variable karyotypes, two overall patterns were present. In one pattern there were at least 12 chromosomal DNA bands, the largest being greater than 2.2 Mb in size; in the other there were more than 15 chromosomal DNA bands, the largest being about 2.0 Mb. The chromosomal DNA preparations included mitochondrial DNA which migrated as a diffuse band between 0.10 and 0.15 Mb in size, and DNA molecules of 8 and 9 kb in size.

Effect of tinfoil substitute contamination on adhesion of resin denture tooth to its denture base.

At least one manufacturer claims that contamination of denture teeth with tinfoil substitute during processing is not detrimental. The purpose of this study was to determine whether tinfoil substitute contamination has any significant effect on the bond strength between acrylic resin denture teeth and their processed acrylic resin base. Eighty acrylic resin maxillary central incisors were processed to denture base material. The experimental group had the denture tooth ridgelap area contaminated with tinfoil substitute. The control group was not contaminated. The bond strength of the two groups was tested. The results indicate that contamination with tinfoil substitute significantly reduces the bond strength of acrylic resin denture teeth bonded to their denture base.

The effect of a surface disinfectant on a dental cast.

This study determined the effect of a disinfectant solution on dental casts. Stone samples were immersed in a disinfectant solution and in control solutions. The results indicate that a saturated calcium sulfate (clear slurry) solution with 0.525% sodium hypochlorite was an effective disinfectant and acted without damage to the dental cast.

Removable prosthodontic laboratory survey.

This article presents a brief review of the literature concerning the curriculum deemphasis for removable prosthodontics, especially on the subject of complete dentures. The authors surveyed commercial dental laboratories specializing in removable dental prosthetics in three major Texas cities to determine whether dentists were submitting adequate records and information with their complete denture work authorizations. Results indicate that dentists are requesting services from their laboratories without providing adequate records.

DNA supercoiling and relaxation by ATP-dependent DNA topoisomerases.

Bacterial DNA gyrase and the eukaryotic type II DNA topoisomerases are ATPases that catalyse the introduction or removal of DNA supercoils and the formation and resolution of DNA knots and catenanes. Gyrase is unique in using ATP to drive the energetically unfavourable negative supercoiling of DNA, an example of mechanochemical coupling: in contrast, eukaryotic topoisomerase II relaxes DNA in an ATP-requiring reaction. In each case, the enzyme-DNA complex acts as a 'gate' mediating the passage of a DNA segment through a transient enzyme-bridged double-strand DNA break. We are using a variety of genetic and enzymic approaches to probe the nature of these complexes and their mechanism of action. Recent studies will be described focusing on the role of DNA wrapping on the A2B2 gyrase complex, subunit activities uncovered by using ATP analogues and the coumarin and quinolone inhibitors, and the identification and functions of discrete subunit domains. Homology between gyrase subunits and the A2 homodimer of eukaryotic topo II suggests functional conservation between these proteins. The role of ATP hydrolysis by these topoisomerases will be discussed in regard to other energy coupling systems.

Postnatal development of the corticotectal projection in cats.

Although numerous physiological studies have provided compelling evidence for the involvement of the corticotectal projection in the normal development of visual response properties of neurons in the superior colliculus, little information is available on the morphological development of corticotectal axons. Thus, our goal was to determine the postnatal changes characterizing the development of the topography and morphology of corticotectal axon arbors. Topographically restricted injections of Phaseolus vulgaris leucoagglutinin were made into striate cortex to label corticotectal axons and their terminal arbors. Following injections of similar size and location in kittens and adult cats, a similar, localized region of the superior colliculus was labeled at all ages. However, while present in the appropriate topographic location in colliculus, the corticotectal projection revealed a greater tangential distribution in kittens than adults. Corticotectal terminal zones underwent a twofold decrease in tangential area during the first 8 weeks after birth. From corticotectal terminal zones in kittens, extended many fine collaterals that ended as growth cones and radiated up to 1 mm from the focus of the terminal zone. By 8 weeks after birth, these immature collaterals were no longer observed, and the corticotectal terminal zone was indistinguishable from those in 12-week-old kittens and adult cats. Corticotectal axon arbors became more specialized in the first 8 weeks after birth; both en passant and terminal swellings increased in diameter, and terminal swellings increased in number, although the total number of swellings per unit length of axon remained relatively stable. The number of axonal branches increased threefold between 1 and 8 weeks after birth. Thus, as the corticotectal projection becomes spatially restricted during development, individual arbors become progressively more intricate with regard to focused collateral branching and the elaboration of complex axonal specializations.