Comparative study of the pathogenicity of avian reoviruses

Reovirus strains CO8 and 81-5, isolated from chickens with malabsorption syndrome, and reovirus strain 176, isolated from chickens with tenosynovitis, were each individually inoculated into 1-day-old specific-pathogen-free chicks. Strain CO8 caused tenosynovitis and pericarditis following footpad inoculation, but it was of low pathogenicity when given by either oral or subcutaneous route. In contrast, strains 81-5 and 176 were highly pathogenic and caused severe mortality following subcutaneous inoculation. Lesions included hepatic necrosis, bursal atrophy, thymitis, and splenic hyperplasia; strain 81-5 also caused pericarditis and myocarditis. Although strain 176 caused higher mortality than strain 81-5, these two strains differed little in the severity and distribution of the lesions they caused. No signs or lesions of typical malabsorption syndrome were observed.     

Durum wheat (Triticum durum Desf.) Mediterranean landraces as sources of variability for allelic combinations at Glu-1/Glu-3 loci affecting gluten strength and pasta cooking quality

With the aim of identifying durum wheat landraces (LR) with a potential use in breeding programs for gluten strength enhancement, the allelic combinations present at five glutenin loci were determined in a collection of 155 LR from 21 Mediterranean countries. A set of 18 modern cultivars (MC) was used for comparison. Gluten strength was determined by SDS-sedimentation test on grain samples from field experiments conducted during 3 years. A total number of 131 different allelic/banding pattern combinations were found. Taking together high (HMW-) and low (LMW-) molecular weight glutenin subunit loci resulted in 126 combinations in LR, but only nine in MC, which are characterized for having strong gluten. Two LMW-2 type models were identified in the collection and LMW-1 types were absent. LMW-2 was present in 78 % of MC, including the only three with outstanding gluten strength (Ocotillo, Claudio and Meridiano), while 14 % of the LR had LMW-2 and 6 % LMW-2^?. In the LR a known combination LMW-2 (aaa) and three new ones had a positive effect on the gluten strength. LMW-2 models were found in high frequency in LR from Italy and the three Maghreb countries; from medium to low frequencies in genotypes from Turkey, Jordan, Lebanon, Portugal and Spain, and were absent in the remaining countries. The large variability found in LR proved their potential value in breeding to broaden the genetic basis of gluten quality improvement. Genotypes interesting for breeding purposes are identified.     

Mercury concentration in tree rings of black spruce (Picea mariana Mill. B.S.P.) in boreal Quebec,Canada

Black spruce from boreal forests located in northeastern Canada (Quebec) were sampled during the summer of 1990, at two stations located at 6° latitude from one another. The objective of the study was to compare the temporal and spatial evolution of mercury in the tree rings of sites with differing degrees of mercury contamination in their soils. Mean mercury tree ring contents ranged from 13 to 37 ng/g, and were more concentrated in the southern than in the northern station. No evident relationship was found between annual growth and corresponding mercury concentrations. The difference in tree ring mercury content associated with geographic orientation of the disks indicates that daily exposure to sunlight as well as temperature may affect mercury uptake, and that the mercury observed in the tree rings must be deposited from the atmosphere onto the tree surface.     

Wild potato (Solanum sect.Petota) germplasm collecting expedition to Mexico in 1993, with special reference toSolanum bulbocastanum Dunal andS. cardiophyllum Lindley

Summary A joint Mexico/United States expedition collected wild potato (Solanum sect.Petota) germplasm in Mexico between August 1–31, 1993. The purpose of the expedition was to expand germplasm and herbarium collections ofS. bulbocastanum andS. cardiophyllum. Collections were made from west-central to southern Mexico, and comprised 19 true seed and 37 tuber collections (45 collections in total) of 9 species and two putative natural hybrids.     

Effects of Mexican dwarf mistletoe (Arceuthobium vaginatum subsp. vaginatum) on the growth of Pinus cooperi in Durango,Mexico—A case study

Mexican dwarf mistletoe (Arceuthobium vaginatum subsp. vaginatum, Viscaceae) is the most widespread and damaging parasitic plant in Mexico. It parasitizes 10 species of pines (Pinus spp., Pinaceae) as principal hosts, including Pinus cooperi, one of the economically most important pines in the state of Durango. As a case study, we used stem analysis to estimate the effects of Mexican dwarf mistletoe on volume and height growth of dwarf mistletoe‐infected P. cooperi in western Durango (Ejido El Brillante, Municipality Pueblo Nuevo). This case study sampled a total of 48 trees, 12 in each of four infection classes estimated using the 6‐class dwarf mistletoe rating system (DMR): uninfected (DMR 0), lightly infected (DMR 1–2), moderately infected (DMR 3–4) and severely infected (DMR 5–6). Significant reductions in both volume and height growth were found for moderately and severely infected trees when compared to uninfected trees. On average, reductions in volume growth and height growth were as high as 50% and 17%, respectively. The largest growth reductions were for moderately infected trees, but large growth reductions also occurred for severely infected trees. Because of the reduced growth associated with moderate to severe infection, Mexican dwarf mistletoe‐infested pine forests in Durango, where timber production is a high priority, should be managed using harvesting practices that reduce dwarf mistletoe infection, and thereby, increase forest productivity.     

Beyond reduced-impact logging: Silvicultural treatments to increase growth rates of tropical trees

Use of reduced-impact logging (RIL) techniques has repeatedly been shown to reduce damage caused by logging. Unfortunately, these techniques do not necessarily ameliorate the low growth rates of many commercial species or otherwise assure recovery of the initial volume harvested during the next cutting cycle. In this study, we analyze the effect of logging and application of additional silvicultural treatments (liana cutting and girdling of competing trees) on the growth rates on trees in general and on of future crop trees (FCTs) of 24 commercial timber species. The study was carried out in a moist tropical forest in Bolivia, where we monitored twelve 27-ha plots for 4 years. Plots received one of four treatments in which logging intensity and silvicultural treatments were varied: control (no logging); normal (reduced-impact) logging; normal logging and low-intensity silviculture; and, increased logging intensity and high-intensity silviculture. Tree growth rates increased with intensity of logging and silvicultural treatments. The growth rates of FCTs of commercial species were 50–60% higher in plots that received silvicultural treatments than in the normal logging and control plots. Responses to silvicultural treatments varied among functional groups. The largest increase in growth rates was observed in FCTs belonging to the partially shade-tolerant and the shade-tolerant groups. These results indicate that silvicultural treatments, in addition to the use of RIL techniques, are more likely to result in a higher percentage of timber volume being recovered after the first cutting cycle than RIL alone.     

Histopathological differences between canine idiopathic sebaceous adenitis and canine leishmaniosis with sebaceous adenitis

Sebaceous adenitis (SA) may be idiopathic (ISA) or associated with other disorders. The purpose of the present study was to compare the cutaneous histopathology of SA in cases in which Leishmania organisms were detected by immunohistochemistry (IHC) with that of cases diagnosed as ISA. Skin sections of 29 patients were evaluated histologically and divided into two groups, one characterized by several epidermal and subepidermal lesions, a granulomatous to pyogranulomatous nodular to diffuse dermatitis involving the sebaceous glands and a positive IHC for Leishmania spp. The other group was characterized by orthokeratotic hyperkeratosis, follicular keratosis with different degrees of pyogranulomatous to granulomatous SA, lack of nodular dermatitis and a negative IHC for Leishmania spp. Hidradenitis was present in both groups. From these results it can be concluded that SA in canine Leishmaniosis (CL) is usually present together with a nodular to diffuse dermal infiltrate and epidermal and subepidermal lesions, and that SA in the absence of dermal inflammation is probably not associated with or suggestive of CL, even in regions where the disease is endemic.