Adapting to climate change: Agricultural system and household impacts in East Africa

The East African region exhibits considerable climatic and topographic variability. Much spatial and temporal variation in the response of different crops to climate change can thus be anticipated. In previous work we showed that a large part of this variation can be explained in terms of temperature and, to a lesser extent, water effects. Here, we summarise simulated yield response in two crops that are widely grown in the region, maize and beans, and investigate how the impacts of climate change might be addressed at two levels: the agricultural system and the household. Regionally, there are substantial between-country and within-system differences in maize and bean production responses projected to 2050. The arid-semiarid mixed crop-livestock systems are projected to see reductions in maize and bean production throughout most of the region to 2050. Yields of these crops in the tropical highland mixed systems are projected to increase, sometimes substantially. The humid-subhumid mixed systems show more varied yield responses through time and across space. Some within-country shifts in cropping away from the arid-semiarid systems to cooler, higher-elevation locations may be possible, but increased regional trade should be able to overcome the country-level production deficits in maize and beans caused by climate change to 2050, all other things being equal. For some places in the tropical highlands, maize and bean yield increases could have beneficial effects on household food security and income levels. In the other mixed systems, moderate yield losses can be expected to be offset by crop breeding and agronomic approaches in the coming decades, while more severe yield losses may necessitate changes in crop types, movement to more livestock-orientated production, or abandonment of cropping altogether. These production responses are indicative only, and their effects will be under-estimated because the methods used here have not accounted for increasing weather variability in the future or changes in the distribution and impacts of biotic and other abiotic stresses. These system-level shifts will take place in a context characterised by high population growth rates; the demand for food is projected to nearly triple by the middle of this century. Systems will have to intensify substantially in response, particularly in the better-endowed mixed systems in the region. For the more marginal areas, the variability in yield response, and the variability in households’ ability to adapt, suggest that, even given the limitations of this analysis, adaptation options need to be assessed at the level of the household and the local community, if research for development is to meet its poverty alleviation and food security targets in the face of global change.     

Seasonal variations and effects of nutrient applications on N and P and microbial biomass under two temperate heathland plants

Eutrofication is a threat against nutrient-poor habitats as increased amounts of nutrients in ecosystems may cause changes in the vegetation. Nitrogen (N) deposition leads to conversion of Calluna heathlands into graminoid dominated heath, but low availability of P may hinder or slow down this process.In this study the soil properties under two dominant heathland plants, the dwarf shrub Calluna vulgaris and the grass Deschampsia flexuosa, were investigated, with focus on nutrient content in the organic top soil and soil microbes during the main growing season and effects of nutrient amendments. The concentration of inorganic and dissolved organic N was significantly higher under D. flexuosa than C. vulgaris all though there were the same amounts of total N in the soil below the two species. N and P amendment enhanced available N and P in the soil, but added nutrients had little direct effects on microbes. The microbial biomass on the other hand was positively related to soil water content in fertilized plots indicating that this was due to an indirect effect of enhanced nutrient availability. Microbial N and P pools were respectively 1000 and 100 times higher than the pool of inorganic N and P, and microbes therefore may play an important role in regulating plant nutrient supply. Judged from responses of inorganic and microbial N and P concentrations to added N and P, N seemed to limit C. vulgaris and soil microbes below while P seemed to limit D. flexuosa and soil microbes below this species. There were lower rates of net nitrification, net ammonification and DOC and DON production rates during winter in the soil under C. vulgaris than below D. flexuosa, although all these rates were equal under the two species on an annual basis. This indicates that these microbial processes were taking place during winter but were affected by exudates from C. vulgaris.     

Staphylococcus hyicus virulence in relation to exudative epidermitis in pigs.

Staphylococcus hyicus strains with different phage types, plasmid profiles, and antibiotic resistance patterns were isolated from piglets with exudative epidermitis. The strains could be divided into virulent strains, producing exudative epidermitis, and avirulent strains, producing no dermal changes when injected in experimental piglets. The results showed that both virulent and avirulent strains were present simultaneously on diseased piglets. This constitutes a diagnostic problem. Concentrated culture supernatants from nine virulent strains injected in the skin of healthy piglets produced a crusting reaction in all piglets. Acanthosis was observed in the histopathological examination of the crustaceous skin. Concentrated culture supernatants from nine avirulent strains produced no macroscopic or microscopic skin changes. Protein profiles from all virulent strains and seven out of nine avirulent strains showed a high degree of protein band homology. An approximately 30 kDa protein present in all concentrated culture supernatants capable of producing skin changes, could not be detected in samples that did not produce skin changes. No other protein showed a similar association. It is concluded that crusting reaction of piglet skin is a suitable indicator of virulence in S. hyicus in relation to exudative epidermitis, and that virulent strains produce a 30 kDa protein, absent in concentrated culture supernatants from avirulent strains. This 30 kDa protein might be an exfoliative toxin.     

Detection of Streptococcus suis by in situ hybridization, indirect immunofluorescence, and peroxidase-antiperoxidase assays in formalin-fixed, paraffin-embedded tissue sections from pigs.

Streptococcus suis is an important pathogen in pigs and is considered a zoonotic agent. To aid diagnosis of infection caused by S. suis, a species-specific probe targeting 16S ribosomal RNA was designed and used for fluorescent in situ hybridization. Two additional immunohistochemical detection methods, an indirect immunofluorescence assay and a peroxidase-antiperoxidase method, using polyclonal antibodies also were developed. The specificity of the oligonucleotide probe was examined by whole-cell and dot-blot hybridization against reference strains of the 35 serotypes of S. suis and other closely related streptococci and other bacteria commonly isolated from pigs. The probe was specific for S. suis serotypes 1-31. The specificity of the polyclonal antibodies, which has previously been evaluated for use in diagnostic bacteriology for typing of serotype 2, was further evaluated in experimentally infected murine tissue with pure culture of different serotypes of S. suis, related streptococci, and other bacteria commonly found in pigs. The polyclonal antibodies against S. suis serotype 2 cross-reacted with serotypes 1 and 1/2 in these assays. The in situ hybridization and the immunohistochemical methods were used for detection of S. suis in formalin-fixed, paraffin-embedded tissue sections of brain, endocardium, and lung from pigs infected with S. suis. The methods developed were able to detect single cells of S. suis in situ in the respective samples, whereas no signal was observed from control tissue sections that contained organisms other than S. suis. These techniques are suitable for determining the in vivo localization of S. suis for research and diagnostic purposes.     

Lung Injury Leading to Respiratory Distress Syndrome in Young Dalmatian Dogs

A progressive pulmonary disease resulting in severe respiratory failure and death in an average of 3 weeks was diagnosed in 11 young Dalmatian dogs. The dogs were from 4 litters, all genetically related by a common ancestor. The initial clinical signs were tachypnea and noisy respiration. Respiratory distress developed shortly before death and was characterized by strenuous and rapid respirations, along with cyanosis and vomiting. On blood gas analysis, there were severe arterial hypoxemia, hypercapma, and marked alveolar-arterial oxygen difference. Radiographically, a diffuse pattern of alveolar, interstitial, and peribronchial densities was observed in the lungs. Most dogs developed pneumomediastinum and gastroesophageal intussusception in the terminal phase of the disease. There was no response to treatment with antibiotics, corticosteroids, diuretics, or oxygen. At necropsy, the lungs were wet, heavy, and relatively airless. Absence of 1 kidney in 2 dogs and severe internal hydrocephalus in 2 dogs were additional necropsy findings. Pulmonary histopathology included metaplasia and atypia of the alveolar and bronchiolar epithelium, a nonpurulent inflammatory reaction characterized mainly by mononuclear cells and macrophages, eosinophilic hyaline membrane formation, and focal pulmonary fibrosis. The histological manifestations were typical of acute lung injury. Clinically, the findings were consistent with adult respiratory distress syndrome (ARDS), except for the relatively long course. No known risk factors for ARDS, such as trauma, toxin exposure, infection, or endotoxemia could be identified. The relationship of the other abnormalities (ie, renal aplasia, hydrocephalus) to the pulmonary disease also remains obscure. An inherited defect is suspected, because segregation analysis of the 4 litters suggests autosomal recessive inheritance.     

5α-Androstenone and Testosterone in Peripheral Plasma of the Boar During and Following Copulation

Copulation was generally followed by increases in peripheral plasma 5α-androstenone and testosterone levels lasting for periods of about 60 to 100 min. The effect of copulation on the plasma levels of these steroids did, however, vary between boars. In seven out of eight boars the maximum levels of 5α-andro-stenone in the period 60 to 100 min. after copulation were from 114 to 218 % (mean 150 %) of the levels in samples collected before copulation. The corresponding figures for testosterone were from 104 to 283 % (mean 190 %). One boar showed decreasing plasma steroid levels after copulation.The coefficient of correlation between the peripheral plasma levels of 5α-androstenone and testosterone was found to be + 0.61 (n = 2.03).     

Different expressions of trypsin and chymotrypsin in relation to growth in Atlantic salmon (Salmo salar L.)

The expressions of trypsin and chymotrypsin in the pyloric caeca of Atlantic salmon (Salmo salar L.) were studied in three experiments. Two internal (trypsin phenotypes, life stages) and three common external factors (starvation, feeding, temperatures) influencing growth rates were varied. Growth was stimulated by increased temperature and higher feeding rate, and it was depressed during starvation. The interaction between trypsin phenotype and start-feeding temperature affected specific activity of trypsin, but not of chymotrypsin. Trypsin specific activity and the activity ratio of trypsin to chymotrypsin (T/C ratio) increased when growth was promoted. Chymotrypsin specific activity, on the other hand, increased when there was a reduction in growth rate whereas fish with higher growth had higher chymotrypsin specific activity resulting in lower T/C ratio value. During a rapid growth phase, trypsin specific activity did not correlate with chymotrypsin specific activity. On the other hand, a relationship between specific activities of trypsin and chymotrypsin could be observed when growth declined, such as during food deprivation. Trypsin is the sensitive key protease under conditions favouring growth and genetically and environmentally affected, while chymotrypsin plays a major role when growth is limited or depressed. Trypsin specific activity and the T/C ratio value are shown to be important factors in the digestion process affecting growth rate, and could be applicable as indicators for growth studies of fish in captive cultures and in the wild, especially when food consumption rate cannot be measured.     

Hemophilia in dogs, with special reference to hemophilia A among German shepherd dogs in Denmark. II: Clinical study, therapy and prophylaxis

Clinical data, pedigrees, screening tests (APTT, PT and TT) and specific tests (VIII:C, VIIIC:Ag, VIIIR:Ag and IX:C) were used to diagnose hemophilia A (classical hemophilia) in two colonies of German Shepherd dogs in Denmark. The affected individuals in both colonies were males, and they descended from a common, hemophilic ancestor. All observations were in accordance with X-linked, recessive inheritance. Therapeutic and prophylactic measures are discussed.