Sprouting can be an important mechanism of regeneration in harvested cypress (Taxodium sp.) wetlands; however, limited information exists on factors influencing sprouting. We examined the influence of harvesting practices, tree size, and site conditions on stump sprouting in eight pondcypress (Taxodium distichum var. nutans (Ait.) Sweet) wetlands in Florida, USA. Stumps were cut at three heights: 20 cm below high water level, at high water, and 40 cm above high water. Half of each site was harvested using a sawhead feller and the other half using shearhead. We monitored sprouting for 2 years post-harvest. Stump height affected first year sprouting, but the effect disappeared during year 2. Felling equipment did not affect sprouting; however, the shearhead caused greater stump damage. Sprouting declined with increasing parent tree size; percentage of stumps with sprouts after 2 years was 68% for trees 10–14 cm dbh and 28% for trees 20–24 cm dbh. Stump sprouting ranged among sites from 23 to 54% after 2 years. Results indicate that sprouting may be an important, but inadequate, form of regeneration. At sites with short hydroperiods, dense understories, and/or predominance of trees greater than 20 cm dbh, reduced sprouting may occur, and planting seedlings may be beneficial. 相似文献
It is likely that in the near future sequence information from sequencing programmes and EST libraries will generate an abundance
of genic microsatellite markers. This study is focused on the assessment of their likely impact and performance vis-à-vis
their genomic counterparts. Microsatellites from two sources were used to assess the genetic diversity in 56 old and new varieties
of bread wheat on the UK Recommended List. A set of 12 microsatellite markers generated from genomic libraries and 20 expressed
sequence tag (EST)-derived microsatellites were used in the study, and the performance of both marker sets assessed. The EST-derived
or genic microsatellites delivered fingerprints of superior quality, amplifying clear products with few stutter bands. Diversity
levels as revealed bygenic microsatellites are similar to the few published results. The PIC values for the genic markers
were generally lower than those calculated for the genomic microsatellites, though advantages of both marker classes for variety
identification applications are discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
Effects of naturally occurring and artificial stimulation on foetal development and the time of hatching were investigated in the fowl, duck and goose.
With respect to natural stimulation, it was shown in the fowl, that the time of hatching is advanced by contact with an egg given 24 h more incubation. Also in the fowl, it was found that contact with other eggs given the same amount of incubation reduces the spread of hatching, although without affecting the mean hatching time. In the Khaki Campbell duck, however, eggs kept in contact hatched earlier than isolates, as well as hatching within a shorter period of time.
The artificial stimulation used was that known to have an accelerating effect in the quail, and the developmental stage of the foetus was assessed by recording pressure changes within the air space of the egg, a method which reveals the time of onset of lung ventilation. When eggs were stimulated artificially it was found in the fowl, duck and goose that the stimulated eggs not only hatched earlier, but began to breathe earlier than did their unstimulated controls. In all three species also, the duration of breathing was shorter in the stimulated than in the unstimulated foetuses. 相似文献
Objective— To determine differences in bacterial strike-through for materials commonly used to cover the distal aspect of the pelvic limb during operative site preparation. Study Design— Randomized block design; ex vivo model. Animals— Canine cadaveric pelvic limbs (n=40). Methods— Pelvic limbs (n=40) were randomly assigned to 4 treatment groups: Group 1=Vetrap™+sterile Coban™; Group 2=latex glove+Vetrap™+sterile Coban™; Group 3=latex glove+Vetrap™+sterile Coban™+sterile latex glove+sterile Coban™; and Group 4=latex glove+Vetrap™+sterile disposable drape+sterile Coban™. Limbs were contaminated with a standardized bacterial solution and routinely prepared using the assigned distal leg wrap. Bandages were fluid challenged with a saline (0.9% NaCl) solution-soaked laparotomy sponge for 30 seconds. The wrap surface was sampled for microbial culture before surgical preparation, immediately after, and 60 minutes after applying a sterile leg wrap. Results— Bacterial growth occurred in all Group 1 cultures, 90% of Group 2 cultures, and none of the Group 3 and 4 cultures, 60 minutes after applying the sterile wrap. Conclusion— A distal leg wrap of Vetrap™+sterile Coban™ is not effective in preventing bacterial strike-through. Clinical Relevance— If similar results occur in the live animal, then a sterile impermeable barrier must be incorporated into the distal leg wrap to prevent bacterial strike-through. 相似文献
A 22-month-old indoor/outdoor neutered male domestic short-haired cat had a history of progressive lethargy, vomiting, and decreased appetite. Abdominal ultrasound revealed an irregular hyperechoic mass in the mid-abdomen. He was unresponsive to symptomatic medical management and was euthanized after 3 days of hospitalization. A diagnosis of disseminated extraintestinal toxoplasmosis was made based on the finding of intracytoplasmic protozoan parasites on histopathological examination of mesenteric lymph nodes, hepatic and intestinal samples, and on immunohistochemistry. 相似文献
In theory, pseudorabies virus (PRV) may be eliminated from any size of breeding herd by phased test and removal if replacement gilts are not infected with PRV, culling decisions are partially based on PRV status, and the cull rate is higher than the incidence rate of PRV. Annual cull rates are commonly at least 50%, but little information exists on the incidence of PRV within enzootically infected swine herds. The purpose of this study was to develop a method by which spread of PRV could be detected among breeding swine within enzootically infected herds and to determine the incidence of PRV infection in these herds. Data were collected from 17 herds that were quarantined for PRV and ranged in size from 120 to 1,100 sows. At each herd, within the first 5 days of introduction, a group of approximately 30 replacement gilts was identified, vaccinated with a glycoprotein X-deleted PRV vaccine, and blood sample was collected. The owner of 1 herd had a nonvaccinated breeding herd and elected to leave incoming gilts nonvaccinated. After vaccination, blood samples were collected every 1 to 2 months for an average of 13.6 months. Serum samples from vaccinated gilts were tested for antiglycoprotein X antibodies by a specific differential ELISA. Samples from nonvaccinated gilts were evaluated by serum neutralization test. Product-limit method was used to estimate the probability of not becoming infected with PRV. Spread was detected in 7 of 8 herds that had more than 400 sows and in 2 of 9 herds that had less than 400 sows.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
1. In eggs turned about 12 times daily, around the long axis of the egg and through about 180 degrees, significant increases in heart rate occurred during turning on the 15th and 17th, although not on the 16th, d of incubation. 2. On and after the 18th d heart rate increases were more marked and occurred both during and after turning. 3. When a single group of embryos was turned every day for the last 4 d of incubation there were significant increases in heart rate on the last 3 d: this repeated retesting had no effect on the response to turning. 相似文献
OBJECTIVE: To compare upper airway mechanics, arterial blood gases, and tracheal contamination in horses with induced left laryngeal hemiplegia (recurrent laryngeal neuropathy [RLN]) treated by laryngoplasty/vocal cordectomy (LPVC) or modified partial arytenoidectomy (MPA). STUDY DESIGN: Repeated measures under the following conditions: Control, RLN, LPVC, and MPA. ANIMALS: Six horses. METHODS: Two trials were conducted under all conditions at 80% and 100% of maximal heart rate (HR(max)). In Trial 1, arterial blood gases, tracheal and pharyngeal pressures, and laryngeal videoendoscopy were recorded. In Trial 2, upper airway pressure and airflow were determined. Tracheobronchial aspirates were performed after exercise to quantify airway contamination. RESULTS: Compared with control, RLN significantly increased inspiratory impedance and worsened exercise-induced hypoxemia. At 80% HR(max), LPVC restored most variables to control values. At 100% HR(max), LPVC improved all variables, but did not restore minute volume, arterial pH, and PaCO(2). At 80% HR(max), MPA restored all variables except bicarbonate to control values. At 100% HR(max), MPA improved all variables, but did not statistically restore minute ventilation or bicarbonate level. Only minor differences were noted between LPVC and MPA. Both resulted in equivalent tracheal contamination. CONCLUSIONS: Airway mechanics and arterial blood gas values were not restored to normal after either LPVC or MPA in horses exercising at HR(max). This does not affect ventilation at sub-maximal exercise, but has clinical implications at HR(max). Both procedures diminish normal laryngeal protective mechanisms. CLINICAL RELEVANCE: At sub-maximal exercise intensities both LPVC and MPA restore airway ventilation to normal. At maximal exercise the superiority of LPVC over MPA is slight. 相似文献