Localization, morphology, and immunohistochemistry of spinal cord and dorsal root ganglion neurons that innervate the gastrocnemius and superficial digital flexor muscles in cattle

OBJECTIVE: To determine the location, morphology, and neurochemical code of spinal cord and dorsal root ganglion neurons that innervate the gastrocnemius muscle (GM) and superficial digital flexor muscle (FDSM) in cattle. ANIMALS: 5 healthy Friesian male calves. Procedure: 2 different types of neuronalretrograde fluorescent tracers (fast blue and diamidino yellow) were injected into the GM and FDSM, respectively. The neurochemical code (substance P, calcitonin gene-related peptide, galanin, and neuronal nuclear protein) of labeled neurons was investigated by immunohistochemistry. RESULTS: Neurons innervating the GM and FDSM were located along the L6-S2 spinal cord segments and ganglionic levels. A cranial-to-caudal topographic distribution for each muscle was found, indicating that the motor nuclei of the 2 muscles are organized by a somatotopic pattern. The GM and FDSM motoneurons were immunoreactive only for calcitonin gene-related peptide, whereas the afferent neurons were immunoreactive for all of the neurochemical markers considered. CONCLUSION AND CLINICAL RELEVANCE: In our study, location and the extent of neurons that supply the GM and FDSM of cattle were characterized completely. Because the GM and FDSM are involved in spastic paresis of calves and it is thought that spastic paresis results from an excessive activity of the neuromuscular spindle reflex arc, findings in our study may be useful for further electrophysiologic and clinical studies. Knowledge of the neurochemical code of neurons that supply the GM and FDSM in healthy calves could be used to compare chemical alterations in the same neuronal population of affected calves.     

Acaricidal properties of the essential oil of Melaleuca alternifolia Cheel (tea tree oil) against nymphs of Ixodes ricinus

The aim of the study was to examine the acaricidal effect of essential oil of Melaleuca alternifolia (tea tree oil, TTO) at different doses (4, 6, 8 and 10 microl) and for different exposure times (30, 60, 90 and 120 min) on nymphs of Ixodes ricinus. A dose of 8 microl TTO was lethal for more than 70% of ticks when inhaled and this effect was enhanced when the dose was increased to 10 microl (> 80%). The effect was correlated with the duration of exposure of ticks to TTO, with a significant effect being observed after 90 min exposure. The findings show that TTO has acaricidal properties and could be extremely useful in controlling ticks that are efficient vectors of pathogens.     

Experimentally induced systemic hyperchloremic acidosis in calves

Background: Among the various metabolic disturbances occurring in calves affected by neonatal diarrhea or ruminal acidosis, acidemia constitutes an important condition requiring specific therapy. Although various attempts have been made to estimate the degree of metabolic acidosis on the basis of clinical signs alone, some doubts have been raised regarding the accuracy and predictive value of the clinical variables suggested. HYPOTHESIS: The induction of metabolic acidosis in healthy calves via the infusion of hydrochloric acid (HCl) will lead to a clinical picture similar to that seen in neonatal calves with diarrhea or ruminal acidosis. ANIMALS: The study was carried out on 15 Holstein male calves between 5 and 19 days of age. METHODS: Hyperchloremic metabolic acidosis was induced over a period of 80 minutes by an IV infusion of 4,000 mL of 0.9% NaCl solution containing 400 mM HCl. RESULTS: Acidemia occurred rapidly and increased constantly up to a maximum value, which was reached in all calves by the end of the administration and amounted to a 22.4 mM/L mean base deficit (range from 17.0 to 33.1 mM/L). Despite the relatively severe acute acid-base imbalance during the entire observation period, no calves showed any clinical signs or depressed appetite. CONCLUSIONS AND CLINICAL IMPORTANCE: Factors other than a disturbance of the acid-base balance should be considered to be primarily responsible for the clinical picture in calves affected by diarrhea or ruminal acidosis.     

Impact of fire on fungal abundance and microbial efficiency in C assimilation and mineralisation in a Mediterranean maquis soil

The present study investigates the impact of fire (low and high severity) on soil fungal abundance and microbial efficiency in C assimilation and mineralisation in a Mediterranean maquis area of Southern Italy over 2 years after fire. In burned and control soils total and active fungal mycelium, microbial biomass C, percentage of microbial biomass C present as fungal C, metabolic quotient (qCO₂) and coefficient of endogenous mineralisation (CEM) were assayed together with several chemical properties of soil (i.e. pH and contents of organic C, total and mineral N, available K, Mg, Mn and water). Fire significantly decreased the fungal mycelium, whereas it stimulated microbial growth probably through the enhancement of bacterial growth because of the increase in organic C and nutrient contents in burned plots. This shift in microbial community composition might explain the observed reduction in soil microbial efficiency of C assimilation (high qCO₂) and the increase in C mineralisation rate (CEM) in the first 84 days after fire. Therefore, fire might increase CO₂ input to the atmosphere not only during combustion phase but also in the post-fire period.     

Genetic analysis of resistance to Phoma tracheiphila in three Citrus and Poncirus progenies

Mal secco is a serious tracheomycosis, caused by the fungus Phoma tracheiphila (Petri) Kanc, et Ghik., which attacks some species of the genus Citrus. The considerable amount of time and space required to evaluate host plant response has discouraged research on the mechanism of inheritance involved in the susceptibility to this disease. The aim of the present work was to study segregation of the resistance trait in three progenies obtained by crossing Citrus latipes (Swing.) Tan., as a female parent, with the male parents Poncirus trifoliata (L.) Raf., C.aurantium L. and C. volkameriana Pasq. Resistance determination was based on natural infections observed over 10 years. Results allowed us to hypothesize three alternative genes (A, B and C) which determine dominant resistance as opposed to susceptibility: the presence of a single allele can thus confer resistance. In addition, we suggest the existence of a fourth gene which, in conditions of dominance, is able to determine susceptibility by nullifying the action of the dominant B allele. Response to the pathogen was also associated with the production of chitinase a PR (pathogenesis-related) protein reported to be present in great quantities in mal secco-resistant Citrus genotypes. Segregation analysis of one F₂ progeny confirmed the hypothesis that the resistance trait is controlled by at least two dominant genes. Further evidence is needed to ascertain whether this hypothesis is applicable to other Citrus species, in which the possibility of other genetic mechanisms being implicated cannot be ruled out, thus making the genetic basis of mal secco resisance more complex.     

Comparison of clinical judgment, Doppler ultrasound, and fluorescein fluorescence as methods for predicting intestinal viability in the pony

Strangulation obstruction was induced in anesthetized ponies for periods of 2 and 3 hours by clamping 45-cm segments of jejunum and associated veins (venous strangulation obstruction) and arteries and veins (arterial and venous strangulation obstruction). Four segments were studied in each of 7 ponies allowed to survive 12 hours, 2 segments in a pony that was allowed to survive 1 hour, and 1 segment in each of 10 ponies allowed to survive 42 days after the strangulation periods ended. Fifteen minutes after the periods of strangulation obstruction ended, the viability of test segments was assessed by clinical judgment (40 segments), fluorescein fluorescence (40 segments), and Doppler ultrasound (32 segments). Because the test segments were normal at necropsy in long-term survivors, all segments were designated as viable. The overall accuracy of the methods used to predict viability was 88% for Doppler ultrasound and 53% each for clinical judgment and fluorescein fluorescence (P less than 0.005). Failures in the last 2 techniques could be attributed to their tendency to score venous strangulation obstruction segments as nonviable (90% for each). Doppler ultrasound was 94% accurate in these segments.