Effects of habitat loss and fragmentation on amphibians: A review and prospectus

Habitat loss and fragmentation are among the largest threats to amphibian populations. However, most studies have not provided clear insights into their population-level implications. There is a critical need to investigate the mechanisms that underlie patterns of distribution and abundance. In order to understand the population- and species-level implications of habitat loss and fragmentation, it is necessary to move from site-specific inferences to assessments of how the influences of multiple factors interact across extensive landscapes to influence population size and population connectivity. The goal of this paper is to summarize the state of knowledge, identify information gaps and suggest research approaches to provide reliable knowledge and effective conservation of amphibians in landscapes experiencing habitat loss and fragmentation. Reliable inferences require attention to species-specific ecological characteristics and their interactions with environmental conditions at a range of spatial scales. Habitat connectivity appears to play a key role in regional viability of amphibian populations. In amphibians, population connectivity is predominantly effected through juvenile dispersal. The preponderance of evidence suggests that the short-term impact of habitat loss and fragmentation increases with dispersal ability. However, species with limited dispersal abilities are likely to be equally imperiled by habitat loss and fragmentation over longer time periods. Rigorous understanding of the effects of habitat loss and fragmentation on amphibians will require species-specific, multi-scale, mechanistic investigations, and will be benefit from integrating large empirical field studies with molecular genetics and simulation modeling. Molecular genetic methods are particularly suited to quantifying the influences of habitat structure across large spatial extents on gene flow and population connectivity. Conservation strategies would benefit by moving from generalizations to species and process specific recommendations and by moving from site-specific actions to implementing conservation plans at multiple scales across broad landscapes.     

Bacterial ecology of ancient Saharan salt‐enrichment ponds at Teguidda‐n‐Tessoumt

Little is known about the bacterial ecology of evaporative salt‐mining sites (salterns) of which Teguidda‐n‐Tessoumt at the fringe of the West African Saharan desert in Niger is a spectacular example with its many‐centuries‐old and very colorful evaporation ponds. During the different enrichment steps of the salt produced as a widely traded feed supplement for cattle, animal manure is added to the crude brine, which is then desiccated and repeatedly crystallized. This study describes the dominant Bacteria and Archaea communities in the brine from the evaporation ponds and the soil from the mine, which were determined by PCR‐DGGE of 16S rDNA. Correspondence analysis of the DGGE‐community fingerprints revealed a change in community structure of the brine samples during the sequential evaporation steps which was, however, unaffected by the brine's pH and electric conductivity (EC). The Archaea community was dominated by a phylogenetically diverse group of methanogens, while the Bacteria community was dominated by gamma proteobacteria. Microorganisms contained in the purified salt product have the potential to be broadly disseminated and are fed to livestock across the region. In this manner, the salt mines represent an intriguing example of long‐term human activity that has contributed to the continual selection, cultivation, and dissemination of cosmopolitan microorganisms.     

Subcritical water extraction of antioxidant compounds from rosemary plants

Subcritical water extraction at several temperatures ranging from 25 to 200 degrees C has been studied to selectively extract antioxidant compounds from rosemary leaves. An exhaustive characterization of the fractions obtained using subcritical water at different temperatures has been carried out by LC-MS, and the antioxidant activities of the extracts have been measured by a free radical method (DPPH). Results indicate high selectivity of the subcritical water toward the most active compounds of rosemary such as carnosol, rosmanol, carnosic acid, methyl carnosate, and some flavonoids such as cirsimaritin and genkwanin. The antioxidant activity of the fractions obtained by extraction at different water temperatures was very high, with values around 11.3 microg/mL, comparable to those achieved by SFE of rosemary leaves. A study of the effect of the temperature on the extraction efficiency of the most typical rosemary antioxidant compounds has been performed.     

Immunochemical approach to detection of adulteration in honey: physiologically active royal jelly protein stimulating TNF-alpha release is a regular component of honey

The presence of royal jelly (RJ) proteins in honey collected from nectars of different plants, origin, and regions and in honeybee's pollen was detected by Western-blot analysis using polyclonal antibodies raised against water-soluble RJ-proteins. The most abundant RJ-protein in honeybee products corresponded to a 55 kDa protein. The N-terminal amino acid sequence of 55 kDa protein was N-I-L-R-G-E. This sequence is identical to the apalbumin-1, the most abundant protein of RJ. Apalbumin-1 is a regular component of honeybee products and thus is a suitable marker tool for proving adulteration of honey by means of immunochemical detection. Its presence in all tested samples of honeys and honeybee pollen was confirmed also by Western-blot analysis using polyclonal antibodies raised against recombinant apalbumin-1. It has been found that major RJ-proteins, apalbumin-1, and apalbumin-2, stimulate mouse macrophages to release TNF-alpha, which demonstrates that physiologically active proteins of honey could be used for its biological valuation.     

Effect of intravenous lidocaine on isoflurane MAC in dogs

Lidocaine decreases minimum alveolar concentration (MAC) of inhalational anesthetics. This study determined the influence of a low dose, 50 µg kg^?1 minute^?1 (LDI) and high dose, 200 µg kg^?1 minute^?1 (HDI) constant rate infusion of lidocaine on the MAC of isoflurane (I) in dogs. Ten mongrel dogs were anesthetized with I in oxygen and mechanically ventilated. End‐tidal anesthetic (Fe ′A) and CO₂ (Pe ′CO₂) concentrations were monitored at the endotracheal tube adaptor with an infrared gas analyzer calibrated before each experiment with a standardized calibration gas mixture designed for the analyzer. Pe ′CO₂ and body temperature were maintained within normal limits. Noxious stimuli included clamping the hindlimb paw (HC) and electrical current (50 V at 50 cycles second^?1 for 10 milliseconds pulse^?1) applied subcutaneously to the forelimb (FE) at the level of the ulna. After an initial equilibration period of at least 40 minutes at an Fe ′A of 1.7%, the Fe ′A was decreased to a value close to the estimated MAC for dogs. MAC was defined as the Fe ′A mid‐way between the value permitting and preventing purposeful movement. Following baseline MAC, a loading dose of 2 mg kg^?1 of lidocaine IV was administered over 3 minutes followed by the LDI, and MAC determinations for the combination started after 30 minutes of infusion. Once determined, the lidocaine infusion was stopped for 30 minutes and the dog maintained at the ETC that prevented movement without the lidocaine. Following this period, a second loading dose of lidocaine was given (2 mg kg^?1) over 3 minutes followed by the HDI, and the MAC determination procedure repeated after 30 minutes of infusion. Data were analyzed using an anova for repeated measures. MAC of I was 1.34 ± 0.035% (mean ± SEM) for both the FE and HC stimuli. The LDI significantly decreased MAC to 1.09 ± 0.043% (18.7% reduction) and HDI to 0.76 ± 0.030% (43.3% reduction). In conclusion, lidocaine infusions decreased the MAC of isoflurane in a dose‐dependent manner.     

Comparison of the hemodynamic effects of halothane alone and halothane combined with epidurally administered morphine for anesthesia in ventilated dogs

The hemodynamic effects of 1.5 minimal alveolar concentration of halothane alone (1.6% end-tidal) and 1.5 minimal alveolar concentration of halothane (1.1% end-tidal concentration) combined with epidurally administered morphine were compared during controlled ventilation in 10 dogs used on 2 occasions and randomly allocated to 2 groups. Arterial blood pressure, cardiac index, stroke volume, left ventricular work, and pulmonary arterial pressure were significantly (P less than 0.05) higher in dogs of the morphine-treated group before administration of morphine. After epidural administration of morphine (0.1 mg/kg of body weight diluted in 0.26 ml of saline solution/kg), hemodynamic changes were not observed, and the aforementioned variables remained significantly (P less than 0.05) higher than values in dogs of the halothane only group. Compared with halothane (1.6%) alone, the reduction in halothane end-tidal concentration (1.1%) associated with epidurally administered morphine is beneficial in maintaining hemodynamic function.     

First step towards integrated pest management on cotton in Burkina Faso

The ‘lutte étagée ciblée’ (LEC), a new spray programme, was tested in Burkina Faso. Each routine insecticide application at a fortnightly interval was followed by scouting and, if necessary, another application based on a threshold, 7 days later. The dosages of the active ingredients used were about half those in the previously recommended 14-day routine treatment programme. On-station trials revealed that the new programme provided the same level of pest control as the previously recommended routine programme. Similar results were obtained in smallholder field trials with yields greater than the fortnightly spraying programme used by the farmers. The amount of insecticide saved by this new programme ranged between 44% and 54%.     

Presymptomatic detection of prions in blood

Prions are thought to be the proteinaceous infectious agents responsible for transmissible spongiform encephalopathies (TSEs). PrP(Sc), the main component of the infectious agent, is also the only validated surrogate marker for the disease, and its sensitive detection is critical for minimizing the spread of the disease. We detected PrP(Sc) biochemically in the blood of hamsters infected with scrapie during most of the presymptomatic phase of the disease. At early stages of the incubation period, PrP(Sc) detected in blood was likely to be from the peripheral replication of prions, whereas at the symptomatic phase, PrP(Sc) in blood was more likely to have leaked from the brain. The ability to detect prions biochemically in the blood of infected but not clinically sick animals offers a great promise for the noninvasive early diagnosis of TSEs.