Sequence evolution in and around the mitochondrial control region in birds

By cloning and sequencing 3.4 kilobases of snow goose mtDNA we found that the ND5 gene is followed by the genes for cytochrome b, tRNA^Thr, tRNA^Pro, ND6, tRNA^Glu, the control region, tRNA^Phe, and srRNA. This order is identical to that of chicken, quail, and duck mtDNA but differs from that of mammals and a frog (Xenopus). The mean extent of difference due to base substitution between goose and chicken is generally closer to the same comparison between rat and mouse but less than that between human and cow. For one of the nine regions compared (tRNA^Glu), the bird differences appear to be anomalous, possibly implicating altered functional constraints. Within the control region, several short sequences common to mammals are also conserved in the birds. Comparison of the goose control region with that of quail and chicken suggests that a sequence element with similarity to CSB-1 duplicated once prior to the divergence of goose and chicken and again on the lineage leading to chicken. Between goose (or duck) and chicken there are four times more transversions at the third positions of fourfold-degenerate codons in mitochondrial than in nuclear genes.Abbreviations CSB conserved sequence block - cytb cytochrome b - ND NADH dehydrogenase - srRNA small-subunit ribosomal RNA Deceased July 21, 1991 Correspondence to: T.W. Quinn at the University of Denver     

Identification of thigmoresponsive loci for cell differentiation inUromyces germlings

Summary The sites alongUromyces appendiculatus germ tubes that are responsive to topographical induction for appressorium formation were determined using glass micropipettes. The germ tubes were perturbed with the micropipettes at different sites and durations. The most responsive region of the germ tubes for appressorium formation was within 0–10 m from the cell apex where >90% of the perturbed germ tubes developed appressoria. Furthermore, only the cell surface in contact with the substratum was responsive. Appressoria could not be induced to form, under any conditions, by perturbing cell-substratum regions of the germ tubes more than 40 m from the apex. Maximum appressorium formation occurred when the perturbing micropipette was left in place for >20 min.     

Differentiation Among Bean Leafroll Virus Susceptible and Resistant Lentil and Faba Bean Genotypes on the Basis of Virus Movement and Multiplication

Systemic movement of Bean leafroll virus (BLRV) in susceptible and resistant lentil and faba bean genotypes was studied using plants grown in a plastic house. All the plants studied were inoculated with BLRV by viruliferous pea aphids (Acyrthosiphon pisum). Five plants/genotype of lentil and faba bean were harvested, respectively, at 3, 6, 9, 12 and 18 days and 1, 2, 3, 4 and 5 weeks after inoculation. Each plant was split into growing point, stem, stem base and root, and each was tested using tissue blot immunoassays (TBIA). Virus concentration in each section was estimated using a 0–3 score and a relative TBIA value was estimated accordingly for each genotype. In susceptible lentil genotypes (ILL 8063 and ILL 2581), BLRV was present in low concentrations in the growing point 3 days after inoculation and in high concentrations in all parts of the plant after 6 days. By contrast, the virus was not detected in the highly resistant genotype (ILL 74) until 18 days after inoculation. In the faba bean genotypes studied, BLRV was detected in high concentrations in all parts of the highly susceptible genotype (Fiord) 1 week after inoculation but only after 3 weeks in resistant genotypes (e.g. BPL 5274), but was not detected in the highly resistant genotypes (BPL 5278 and BPL 5279) 5 weeks after inoculation. The replication and systemic movement of BLRV was thus slower in resistant genotypes than in susceptible genotypes. Moreover, the use of TBIA scores clearly and easily differentiated resistant and susceptible genotypes. Our results suggest that BLRV movement and multiplication can be useful criteria when differentiating resistant from susceptible genotypes. In addition, undertaking the preliminary screening in a plastic house requires less space than direct planting in the field.     

Cryptosporidium anserinum sp. n. (Sporozoa) in a Domestic Goose Anser anser L., from Iowa

SYNOPSIS. Cryptosporidium anserinum sp. n. is described in the large intestinal mucosa of a domestic goose, Anser anser L., from Iowa. Ultrastructural studies revealed schizonts containing 4 merozoites and macrogametes and schizonts with characteristic attachment zones and double membranes. The only lesion associated with infection was shortening of the intestinal microvilli.     

Glycosylation is not needed for the intracellular transport of phytohemagglutinin in developing Phaseolus vulgaris cotyledons and for the maintenance of its biological activities

Approximately 10% of the total protein contained in Phaseolus vulgaris L. cv. Greensleeves seeds is composed of the glycoprotein lectin, phytohemagglutinin. We have investigated whether the presence of N-linked oligosaccharide side chains is a prerequisite for the correct intracellular transport of this protein and whether unglycosylated phytohemagglutinin maintains its biological activities. Excised developing cotyledons were incubated in the presence of tunicamycin to prevent glycosylation "in vivo", and the fate of the unglycosylated protein synthesized in such cotyledons determined. It was found that unglycosylated phytohemagglutinin reaches its normal site of accumulation, the protein bodies, and maintains erythro-agglutinating and mitogenic activities.     

The response of field grownPhaseolus vulgaris to Rhizobium inoculation and the quantification of N2 fixation using15N

Summary A field experiment was performed to assess the effects of Rhizobium inoculation and nitrogen fertilizer (100 kg N ha^–1) on four cultivars of Phaseolus beans; Carioca, Negro Argel, Venezuela 350 and Rio Tibagi. In the inoculated treatment 2.5 kg N ha^–1 of¹⁵N labelled fertilizer was added in order to apply the isotope dilution technique to quantify the contribution of N₂ fixation to the nutrition of these cultivars.Nodulation of all cultivars in the uninoculated treatments was poor, but the cultivars Carioca and Negro Argel were well nodulated when inoculated. Even when inoculated, nodulation of the cultivars Venezuela 350 and Rio Tibagi was poor and these cultivars showed little response to inoculation in terms of nitrogen accumulation or grain yield. The estimates of the contribution of N₂ fixation estimated using the isotope dilution technique, for the Carioca and Negro Argel cultivars, amounted to 31.7 and 18.4 kg N ha^–1 respectively. These two cultivars produced 991 and 883 kg ha^–1 of grain, respectively, when inoculated and 663 and 620 kg ha^–1 with the addition of 100 kg N ha^–1 of N fertilizer. The response to nitrogen was particularly poor due to high leaching losses in the very sandy soil at the experimental site.The Venezuela 350 and Rio Tibagi cultivars only responded to N fertilizer and not to inoculation with Rhizobium which stresses the great importance of selecting plant cultivars for nitrogen fixation in the field.     

Ultrastructural and cytological changes in the muscle fibers of the pectoralis of the giant Canada goose (Branta canadensis maxima) in disuse atrophy during molt

Summary Adult male Branta canadensis maxima were collected from a nonmigratory feral population during their premolt, molt and postmolt phases. Lean dry weight of the pectoralis muscle decreased significantly (p0.0001) during molt, as a result of disuse atrophy. Histochemical analysis revealed that the region of the pectoralis muscle sampled consisted of Red (fast-twitch oxidative-glycolytic) and White (fast-twitch glycolytic) muscle fiber types, in an approximate ratio of 9 to 1. There was no significant (p= 0.1238) difference in the relative percentages of the two fiber types during the three periods of study. There was, however, a significant decrease in mean cross-sectional area of both Red (p0.0194) and White (p0.0001) fibers during molt. Red and White fiber areas were strongly correlated with each other during molt (r ²=0.76, p=0.0010) and postmolt (r ²=0.70, p=0.0052), but not during premolt (r ²=0.02, p=0.7626). The latter finding may be related to fiber-type specific hypertrophy in premolt breeding males. Analysis of ultrastructure revealed that there was a significant (p=0.0003) decrease in the mean myofibrillar crosssectional area, and a significant increase in both the density (p=0.0227) and total number (p=0.0058) of myofibrils within the muscle fibers of the molting birds. These results indicate that the myofibrils split longitudinally during moltassociated disuse atrophy. A significant (p=0.0375) reduction in the amount of non-myofibrillar material (mitochondria) was also observed in the periphery of the muscle fibers of the molting birds. The changes observed during disuse atrophy are neither as pathological nor as extreme as those induced by experimental models of avian muscle atrophy.     

Isoenzyme status and genetic variability of serum esterases in the lesser snow goose,Anser caerulescens caerulescens

A maximum of 22 bands comprising four esterase subgroups—acetylesterase, carboxylesterase, cholinesterase, and acetylcholinesterase—were detected following electrophoresis of lesser snow goose sera on polyacrylamide gels. A minimum of seven structural genes was surmised to be involved in the biosynthesis of these enzymes following physiochemical characterizations. The genetic variability of these loci was calculated to be 1.25% average heterozygosity, while 14.3% of the loci were polymorphic. These estimates of genetic variability were substantially lower than those reported for other vertebrate species. The low degree of genetic variability found in snow goose serum esterases coupled with the extensive protein multiplicity observed may possibly reflect an adaptive strategy based on biochemical plasticity rather than genic heterozygosity for this species. The nature of evolutionary forces acting upon multiple enzyme systems such as esterases is discussed. The concept of conditional neutrality is introduced and defined within this context.This research was carried out under grants from the National Research Council of Canada and the Canadian Wildlife Service to F. Cooke. J. Grossfield was supported by grants from the National Institutes of Health, GM 21630 and FRAP 10576.     

Using 2 Genetic Markers to Discriminate Among Canada Goose Populations in Ohio

Abstract: Canada goose (Branta canadensis) harvest management depends on reliable estimates of harvest composition, and established genetic methods provide an alternative to traditional methods. We expanded upon previous genetic studies by comparing the utility of 6 nuclear microsatellite loci and mitochondrial (mtDNA) control region sequences for discriminating among giant (B. c. maxima) and interior (B. c. interior) populations in Ohio (USA) Canada goose harvests at both individual and population levels. Subspecies and populations exhibited greater differentiation in mtDNA (F_ST = 0.202) than microsatellites (F_ST = 0.021), as would be expected based on differences in effective population size. Neither microsatellites nor mtDNA alone were sufficient for estimating harvest composition at the subspecies or population level in simulations and empirical blind tests using individuals of known origin; however, a combined microsatellite + mtDNA dataset yielded accurate and precise harvest derivations at the subspecies level. Both population-level mixed stock analysis and individual-level assignment tests provided accurate results, but a large proportion of birds could not be assigned with confidence at the individual level. We applied mixed stock analysis and the combined microsatellite + mtDNA dataset to Ohio's 2003–2004 harvest and found that interior populations accounted for 4.9% (95% CI = 1.7–8.0%) of the statewide early season and 9.3% (95% CI = 6.9–11.6%) of the regular and late-season harvested sample. These results suggest that maximum likelihood harvest derivations are highly dependent on the choice of genetic markers. Studies should only employ markers that exhibit sufficient variation and have been shown through simulations and empirical testing to accurately discriminate among the subspecies or management populations of interest.