Reproductive dominance of pasture trees in a fragmented tropical forest mosaic

Tropical forest fragmentation threatens biodiversity, yet basic information on population responses for major groups such as plants is lacking. Hypervariable genetic markers were used to reconstruct a population-level pedigree in fragmented tropical forest for the tree Symphonia globulifera. Though seedlings occurred only in remnant forest, the pedigree showed that most seedlings had been produced by sequentially fewer adults in pasture, creating a genetic bottleneck. The pedigree also implicated shifts in the foraging of animals that disperse pollen and seed in a secondary constriction of the bottleneck. These results suggest that tropical conservation strategies should anticipate complex, cryptic responses to fragmentation.     

THE LEGUME—A REAPPRAISAL OF ITS PLACE IN TODAY'S FARMING*

The last 10 years have seen a marked shift in Britain from the growing of legumes towards the use of fertilizer N. Many farmers are now reassessing the position Decause of increasing fertilizer prices and because of improvements in clovers and lucerne through plant breeding. On the intensive dairy farm legumes can play an important part in the conseravation block. The yield of lucerne without applied N is as high as from ryegrass with 250 units N/ac. Red clover is also useful over a wide range of soil types. On the less intensive farm, white clover should be contributing throughout the grazing area. there are many reasons for poor white clover populations in pastures; one of these is the fungus disease Sclerotinia trifoliorum, commonly known as clover rot. Varieties resistant to this disease are available in both red and white-clover. Verticillium wilt in lucerne bas also been checked by the plant breeder. Improved legume varieties justify a completely new look at these crops and the possibilities for lucerne in this country appear to be particularly good.     

A COMPARISON OF RYEGRASS VARIETIES FOR EARLY–BITE PRODUCTION

The value of varieties of Italian, hybrid and Westerwold ryegrass for early-bite production was compared at 32 centres in different environments. The relative performance of Italian ryegrass varieties was fairly consistent from centre to centre over a period of 3 years. Danish and Leda Daehnfeldt Italians produced the most, and S22 the least, early spring production. Good early-bite and total annual yields were obtained from hybrid ryegrasses. Swards sown in the previous autumn were more winter-hardy than spring-sown swards and appeared to be as early in the following year.     

Chloroplast DNA variation of northern red oak (Quercus rubra L.) in Indiana

Chloroplast DNA (cpDNA) variation was examined in 48 northern red oaks at 14 sites representing contrasting glacial histories and age structures within the state of Indiana in the United States. PCR-RFLP of three intergenic regions revealed five haplotypes. Haplotype I was common to seven sites and was the most frequent (17 trees). Haplotype II was common to five sites and was nearly as frequent as haplotype I (16 trees). Haplotypes III, IV and V were equally infrequent and did not occur together. Genetic diversity resided among rather than within populations (G_ST = 0.73 ± 0.14). This preliminary survey shows that cpDNA diversity will be a useful tool for the investigation of ancient seed dispersal patterns in northern red oak.     

Successful ventilatory management of post‐anesthetic airway collapse and hypoxemia in a dog

Abstract Objective: To report a life‐threatening complication (airway collapse) associated with a common procedure (anesthesia) and to describe its successful management. Case Summary: A dog without pre‐existing signs of respiratory disease developed hypoxemia and severe atelectasis in the post‐anesthetic recovery period and was demonstrated, by bronchoscopic examination, to have severe airway collapse. Mechanical ventilation was used to re‐expand collapsed lung units and to prevent re‐collapse. A ventilation strategy designed to minimize airway and alveolar trauma was used. The dog was successfully weaned from the ventilator and made a full recovery. Unique Information Provided: Acute, severe hypoxemia due to airway collapse occurred in the post‐operative period in a dog with no signs of pre‐existing respiratory disease. The dog was successfully managed with short‐term mechanical ventilation. High frequency jet ventilation was used for a diagnostic bronchoscopy.     

Ovine rumen papillae biopsy via oral endoscopy; a rapid and repeatable method for serial sampling

AIMS: To explore and validate the utility of rumen endoscopy for collection of rumen papillae for gene expression measurement.

METHODS: Four adult Coopworth ewes were fasted for either 4 or 24 hours. Animals were sedated, placed in a dorsally recumbent position at 45 degrees with the head upright, and an endoscope inserted via a tube inserted into the mouth. Biopsies of rumen papillae were taken from the ventral surface of the rumen atrium under visual guidance. Two biopsies were collected from one of the animals that had been fasted for 4 hours, and three from one of the animals that had been fasted for 24 hours. Video of the rumen atrium and reticulum was also collected. The animals recovered uneventfully. Biopsies were subsequently used for extraction and sequencing of mRNA.

RESULTS: The ventral surface of the rumen atrium was accessible after 4 hours off pasture, but a larger region was accessible after 24 hours of fasting. Sedation allowed access for endoscope use for around 5 to 10 minutes after which increased saliva flow was noted. Rumen papillae biopsies were easily collected, with samples from a variety of sites collected in the ～10 minute time window. High quality RNA was obtained for stranded mRNA sequencing. Of the resulting reads, 69–70% mapped uniquely to version 3.1 of the ovine genome, and 48–49% to a known gene. The rumen mRNA profiles were consistent with a previously reported study.

CONCLUSIONS: This method for obtaining rumenal tissue was found to be rapid and resulted in no apparent short or long term effects on the animal. High quality RNA was successfully extracted and amplified from the rumen papillae biopsies, indicating that this technique could be used for future gene expression studies. The use of rumen endoscopy could be extended to collection of a variety of rumen and reticulum anatomical measurements and deposition and retrieval of small sensors from the rumen. Rumen endoscopy offers an attractive and cost effective approach to repeated rumen biopsies compared with serial slaughter or use of cannulated animals.     

Influence of Osteopontin in Bovine Uterine Tube Fluid on Sperm Binding and Fertilization in RCA-1 Lectin-treated Oocytes

This study was conducted to determine the effect of pre‐exposure of oocytes to Ricinus communis (RCA‐1) lectin and osteopontin (OPN) in uterine tube fluid (UTF) on in vitro sperm–egg binding and fertilization. In vitro‐matured bovine oocytes were incubated (39°C, 5% CO₂ in air) for 2 h in the following treatments: (i) 500 μl of fertilization medium (FM); (ii) 250 μl of FM with 0.25 ml of non‐luteal ampullary uterine tube fluid (NLAUTF); (iii) 250 μl of FM with 250 μl of NLAUTF and 4 μl of RCA‐1 lectin; (iv) 250 μl of FM with 250 μl of NLAUTF, a rabbit polyclonal antibody (1:200) against purified bovine milk OPN, and RCA‐1 lectin; (v) 500 μl of FM and RCA‐1 lectin. Following incubation, oocytes were washed, placed in FM with 2 μg heparin, and incubated with 1 × 10⁵ frozen–thawed spermatozoa per 10 oocytes. Oocytes used to assess sperm binding were stained with Hoescht 33342, and the number of sperm bound per zona pellucida counted. The remaining oocytes were fixed in acid alcohol, stained with 1% acetate‐orcein and observed to determine the presence of pronuclei. More sperm bound to the zona pellucida (mean ± SEM) when oocytes were incubated in treatment 3 (59.0 ± 5.5) than in treatments 2 (46.4 ± 5.6), 4 (18.1 ± 5.4), 5 (33.4 ± 5.6) or 1 (32.5 ± 5.6). More oocytes were fertilized when incubated in treatment 3 (91% ± 3.0) than in 2 (84% ± 3.0), 4 (40% ± 3.0), 5 (77% ± 3.0) or 1 (76% ± 3.0). As in previous studies, this study suggests that RCA‐1 lectin enhances binding of UTF‐derived OPN to bovine oocytes, resulting in increased sperm–egg binding and fertilization in vitro and a possible role in fertilization.