Dall''s sheep responses to overflights by helicopter and fixed-wing aircraft

High rates of behavioural disruption caused by human activities could jeopardize the body condition and reproductive success of wildlife. I exposed Dall's sheep (Ovis dalli dalli) of the Yukon Territory to experimental overflights by a fixed-wing aircraft and a helicopter. Aircraft approaches that were more direct (as determined by the aircraft's elevation and horizontal distance from sheep) were more likely to elicit fleeing or to disrupt resting. Latency to resume feeding or resting after fixed-wing overflights was longer during more direct approaches. During indirect approaches by helicopters, sheep far from rocky slopes were much more likely to flee than sheep on rocky slopes. Sheep did not flee while nearby helicopters flew along the opposite side of a ridge, presumably because the obstructive cover buffered disturbing stimuli. Results provide preliminary parameters for predicting energetic and fitness costs incurred as a function of overflight rates, and can help mitigate disturbance by guiding temporal and spatial restrictions to aircraft.     

Phylogeny and nodulation signal molecule of rhizobial populations able to nodulate common beans—other than the predominant species Rhizobium etli—present in soils from the northwest of Argentina

We examined the bean rhizobia community other than the predominant species Rhizobium etli present in soils of a region that is part of the range occupied by the host in Northwest Argentina, which showed Rep and 16S rDNA RFLP polymorphism. Two populations represented by isolates T29N3L and T44N22P were found to be distinct chromosomal genotypes and closely related to species Rhizobium tropici and Agrobacterium rhizogenes. Their symbiotic genes were analyzed and found to cluster with those from R. tropici as well as with rhizobia isolated from leguminous trees. Three nodulation metabolites produced by T44N22P were detected which are tetra- and pentameric chitocompounds, N-methylated, O-carbamoylated, and N-substituted either by a C_18:0 or C_18:1 acyl chain at their non-reducing end, and all them sulphated at the reducing end. Isolates T29N3L and T44N22P exhibited broad host range but unlike T29N3L, only T44N22P was able to efficiently nodulate Medicago truncatula.     

Countercurrent supercritical fluid extraction and fractionation of high-added-value compounds from a hexane extract of olive leaves

Countercurrent supercritical fluid extraction (CC-SFE) at a pilot scale plant was used for fractionation of high-added-value products from a raw extract of olive leaves in hexane. Compounds found in the raw extract were waxes, hydrocarbons, squalene, beta-carotene, triglycerides, alpha-tocopherol, beta-sitosterol, and alcohols. The CC-SFE extraction process was investigated according to a 2(3) full factorial experimental design using the following variables and ranges: extraction pressure, 75-200 bar; extraction temperature, 35-50 degrees C; and ethanol as modifier, 0-10%. Data were analyzed in terms of extraction yield, enrichment, recovery, and selectivity. Higher extraction yields were attained at 200 bar. For most of the compounds analyzed enrichment was attained at the same conditions, that is, 75 bar, 35 degrees C, and 10% ethanol. Hydrocarbons were usually recovered in the separators, whereas waxes and alpha-tocopherol remain in the raffinate. Selectivity data reveal that alpha-tocopherol is the most easily separable compound. The influence of the experimental factors on the recovery of all the compounds was studied by means of regression models. The best fitted model was attained for beta-sitosterol, with R2 = 99.25%.     

Remediation of As-Contaminated Soils in the Guadiamar River Basin (SW, Spain)

In 1998, the pond containing the ore wastes from a pyrite mine in Aznalcóllar (SW, Spain) broke open, spilling some 36×10⁵ m³ of acidic waters and 9?×?10⁵ m³ of tailings containing high concentrations of As and heavy metals. The affected area was around 55 km² of predominantly agricultural soils. After the clean-up of the tailings, many remediation actions were undertaken and the use of blocking agents to immobilize the As was one of the most extended measure. The first experiment performed was to determine the most important soil components in As adsorption under acidic conditions. A second experiment was conducted to neutralize the acidity caused by the solution coming from the tailings undergoing oxidation; an adequate liming material (sugar-refinery scum) was selected and the application rates were established. After the remediation measures, the zone was monitored for three years. A detailed study in four experimental plots located in the most polluted sector was carried out to test the influence of iron oxides in the As immobilization. The use of red soils of the area (rich in free-iron oxides Fe_d) was established as an appropriate material in the remediation of the area.     

Status and distribution of the Mediterranean monk seal Monachus monachus on the Cabo Blanco peninsula (Western Sahara-Mauritania) in 1993–1994

The current geographical distribution of the Mediterranean monk seal Monachus monachus colony inhabiting the Cabo Blanco peninsula (Western Sahara-Mauritania) is described. Its distribution range has apparently not changed since surveys conducted in 1984–1988. Sightings of adults on the Tarf el Guerguerat coast, 20 km north of the known breeding caves, suggests the existence of other possible breeding groups further north. Two caves used by the seals are described for the first time. A review of historical trends in cave occupation by seals made it possible (1) to locate the so-called ‘maternity cave’, last reported in 1949; and (2) to establish that the colony, since its discovery, has occupied at least eight caves, five of which have collapsed. An index of population size based on counts of individuals of identified morphological types indicates that, during 1993–1994, the colony was composed of c.113–165 individuals (excluding pups), a larger number than previously assumed. Counting of seals at times of maximum haul-out is proposed as a tool to monitor population trends, although it is considered unreliable for estimating absolute numbers.     

Ultrasensitive detection of genetically modified maize DNA by capillary gel electrophoresis with laser-induced fluorescence using different fluorescent intercalating dyes

In this work, four different fluorescent intercalating dyes are compared for the ultrasensitive CGE-LIF detection of DNA from transgenic maize in flours. The fluorescent intercalating dyes compared are YOPRO-1, SYBR-Green-I, Ethidium bromide (EthBr), and EnhanCE. For all the four dyes optimum concentrations are established, and efficient separations of DNA fragments ranging in size from 80 to 1000 bp are obtained. The comparative study demonstrates that SYBR-Green-I and YOPRO-1 provide better limits of detection (LODs) than EnhanCE or EthBr (i.e., LODs are, respectively, 700, 1000, 11300, and 97400 zmol, calculated for a 200-bp DNA fragment). Separations using YOPRO-1 are faster than those using SYBR-Green-I (30 min vs 47 min for the analysis of the 80-1000 bp DNA fragments). Also, separations using YOPRO-1 are more efficient than those using SYBR-Green-I (e.g., 2.4 x 10(6) plates/m vs 1.6 x 10(6) plates/m, respectively, calculated for the 200-bp fragment). Also, buffer depletion and cost per analysis are worse with SYBR-Green-I than with YOPRO-1. Therefore, YOPRO-1 was selected as the preferred intercalating dye. Using this fluorescent compound, analysis time reproducibility for the CGE-LIF separation of the DNA fragments is determined to be better than 1.7% (% RSD, n = 10) within the same day, and better than 1.9% (% RSD, n = 30) for three different days. Moreover, the fluorescence signal obtained using this dye is shown to vary linearly with the DNA concentration in the range studied, i.e., 1-500 ng/microL. It is demonstrated that by using this method 0.01% of transgenic maize can be detected in flour by direct injection of the PCR-amplified sample.     

The growth curve of animals

Several analytical expressions have been proposed as models of weight versus time to describe growth but these have not been completely satisfactory. Some of them represent a good adjustment for only a part of the growth process; others have parameters of little biological significance or not enough practical interpretation. Some also involve troublesome numerical work, or do not have enough flexibility to accommodate exceptional cases.In this study, a simple flexible and analytical expression with biologically significant parameters is presented. In the authors' opinion this expression eliminates many of the deficiencies mentioned above.The proposed expression is validated with data available in the literature. Cases were selected and used to show the adequacy of the expression for adjusting quantitative variations between and within species.     

Microscopic postmortem changes in adrenal glands of the domestic fowl

Eighty-four male white leghorn chickens were killed by CO2 gas to determine the type, rate, and sequence of microscopic postmortem changes in the adrenal glands of dry and wet intact carcasses. They were held at 29 or 18 C with 50% relative humidity for different times postmortem. The sequence of microscopic postmortem changes was similar in all chickens except at 18 C, when karyorrhexis of cortical and medullary cells was observed. Cellular changes occurred earlier at 29 C than at 18 C and in dry chickens but not in chickens wet with detergent solution before storage, although slight quantitative and qualitative differences between wet and dry chickens were noted. Medullary cells underwent postmortem changes earlier than cortical cells. Nuclei of medullary cells decreased in size, with chromatin clumping leading to pyknosis, followed by cytoplasmic vacuolation, cellular shrinkage, and finally karyolysis and cell dissociation. Cortical cells had nuclear chromatin marginated, nuclei reduced in size initially, and some nuclear fading, followed by pyknosis and karyolysis. Karyorrhexis was not a prominent feature of cortical and medullary cells, although it occasionally occurred before pyknosis. Cytoplasm of cortical cells remained eosinophilic, granular, and vacuolated, but vacuoles became finer later. Pyknotic medullary cells with vacuolated cytoplasm were observed as early as 3 hr postmortem, regardless of the temperature. Diffuse pyknosis of medullary cells was noted at 18 hr in chickens held at 29 C and at 48 hr in chickens held at 18 C. Marked cortical pyknosis was noted only at 36 hr in wet chickens held at 29 C, when bacterial invasion started. Dry chickens held 36 hr at 29 C had diffuse cellular dissociation, karyolysis and cytoplasmic acidophilia, and marked bacterial invasion. Erythrocytes were pyknotic and had cytoplasmolysis. It was concluded that adrenal glands may still be useful for histopathological examination before 18 hr at 29 C and before 48 hr at 18 C.     

Anaplasma marginale: lack of cross-protection between strains that share MSP1a variable region and MSP4

In Mexico, there are no commercial alternatives for the immunoprophylaxis of bovine Anaplasmosis, a disease responsible for great economic losses. Blood derived Anaplasma marginale used for immunizing susceptible cattle has shown promising results for homologous protection and controversial results against unrelated strains. The present study examined, under controlled conditions, the cross-protective potential of an immunogen composed of blood derived A. marginale of three strains against challenge with strains not included in the immunogens. Groups 1 and 2 were immunized with blood derived Anaplasma from strains Mexico, Morelos and Yucatan, group 4 with strains Morelos, Veracruz and Yucatan, two more groups (2 and 5) of equal conditions were inoculated with an adjuvant alone. Groups 1, 4 and 5 were challenged with Mexico strain; groups 2 and 3 were challenge-inoculated with strain Veracruz; groups 3 and 5 with strains Veracruz and Mexico as controls. Only animals in group 1, immunized and challenged with strain Mexico showed adequate protection. Both groups challenged with strains not included in the immunogens developed poor protection, while all the controls had to be treated to prevent death.