Studies on the host/parasite interface during the development of a pentastomid arthropod parasite in rodent intermediate hosts, with observations on protective surface membranes

The changing structure of the cuticle of the arthropod pentastomid parasite Porocephalus crotali, during growth to the infective stage in mouse and rattlesnake hosts, is described. The outermost cuticulin layer of the cuticle in instars II-VI is elevated to form a dense mat of epicuticular hairs. Since the VI larval cuticle is retained by the infective (VII) nymph as a protective sheath, effectively all stages in mice present a hairy surface to the host and this may constitute a physical barrier to inflammatory cells. The entire surface is overlain by a triple-track 'unit' membrane whose biophysical properties resemble those of a conventional plasma membrane, and there is evidence to suggest that this membrane is susceptible to immune attack. Under natural circumstances, epicuticular hairs entrap secretion, delivered to the cuticle via innumerable minute ducts which communicate with tegumental secretory cells termed subparietal cells (SPC). SPC synthesize lamellate droplets which unfold on the cuticle to constitute a layer of protective polymorphic vesicles. By contrast, infective nymphs in snakes possess a smooth cuticle and SPC membranous secretion is stacked over the entire surface, in sheets up to 20 deep. The function of the lipid and protein components of SPC secretion is discussed.     

Fine structural aspects of secretory processes in a pentastomid arthropod parasite in its mouse and rattlesnake hosts

The histology and development of three extensive glands in the porocephalid pentastomid Porocephalus crotali is described by light and electron microscopy, during growth of the parasite to an infective stage in the tissues of mouse; the infective stage in rattlesnake definitive hosts is also included. These glands elaborate excretory/secretory components which are channelled, via chitin-lined efferent ductules, on to the parasite cuticle. Hook and frontal glands are relatively compact, and within each gland ductules serving individual secretory lobules collect into common ducts which discharge over each of the four hooks, or at the anterior margin of the cephalothorax respectively. Subparietal gland cell lobules, composed of two large and two small secretory cells, are distributed under the cuticle and each is served by a single efferent ductule; these erupt over the entire cuticle. The large cells in subparietal glands secrete lamellate droplets which coat the cuticle with thin layers. Identical cells are found in hook and frontal glands, in addition to to three morphologically distinct types of protein secretory cell. Preliminary data on the composition and immunological properties of the various secretory products are presented.     

The linkage of sialic acid in the Ehrlich ascites-carcinoma cell surface membrane

1. The sialic acid content of fresh and fixed Ehrlich ascites cells was determined by incubation with neuraminidase and analysis of the supernatants. 2. The content of sialic acid was also determined on ultrasonically disrupted cells either with or without prior neuraminidase treatment, and the location of sialic acid in the cell is discussed. 3. The sialic acids, cleaved from cells by neuraminidase, were identified chromatographically. 4. Proteolytic enzymes were used to isolate from cells a mucopeptide containing sialic acid and galactosamine in almost equimolar proportions. 5. The nature of the carbohydrate-amino acid bond in the muco-peptide was investigated by alkaline hydrolysis. 6. A suggestion is made about the particular amino acids involved in the sugar-peptide bond.     

Normal and expanded Huntington's disease gene alleles produce distinguishable proteins due to translation across the CAG repeat.

BACKGROUND: An expanded CAG trinucleotide repeat is the genetic trigger of neuronal degeneration in Huntington's disease (HD), but its mode of action has yet to be discovered. The sequence of the HD gene places the CAG repeat near the 5' end in a region where it may be translated as a variable polyglutamine segment in the protein product, huntingtin. MATERIALS AND METHODS: Antisera directed at amino acid stretches predicted by the DNA sequence upstream and downstream of the CAG repeat were used in Western blot and immunohistochemical analyses to examine huntingtin expression from the normal and the HD allele in lymphoblastoid cells and postmortem brain tissue. RESULTS: CAG repeat segments of both normal and expanded HD alleles are indeed translated, as part of a discrete approximately 350-kD protein that is found primarily in the cytosol. The difference in the length of the N-terminal polyglutamine segment is sufficient to distinguish normal and HD huntingtin in a Western blot assay. CONCLUSIONS: The HD mutation does not eliminate expression of the HD gene but instead produces an altered protein with an expanded polyglutamine stretch near the N terminus. Thus, HD pathogenesis is probably triggered by an effect at the level of huntingtin protein.     

A simplified laparoscopy technique for repeated ovarian observation in the water buffalo (Bubalus bubalis)

A simplified technique of laparoscopy was developed for ovarian observation in the riverine buffalo, through a right paralumbar incision. The technique differed from previously described ones in that it involved only a single puncture and required no abdominal insufflation. A Hopkins 0 degrees forward viewing endoscope (5.5 mm x 500 mm) in combination with an endoscope sheath having a built-in instrument channel, and a long flexible forceps (630 mm) were used. Of the 23 observation attempts on 13 buffalo, 21 successful observations were conducted. Laparoscopies were performed using a combination of Xylazine, local infiltration and epidural anesthesia in a standing position. Six repeated observations were made within a 21-day period on 1 buffalo, with no postoperative complications. Observation of both left and right ovaries was possible through the same puncture. The technique was useful in buffalo to confirm ovarian structures which could not be determined with certainty through palpation per rectum. Our results suggest that the single puncture laparoscopy technique can be safely used for repeated ovarian examination in the water buffalo.     

A Comparison of Remote Sensing and Ground-Based Methods for Monitoring Wetland Restoration Success

Abstract Efficient and accurate vegetation sampling techniques are essential for the assessment of wetland restoration success. Remotely acquired data, used extensively in many locations, have not been widely used to monitor restored wetlands. We compared three different vegetation sampling techniques to determine the accuracy associated with each method when used to determine species composition and cover in restored Pacific coast wetlands dominated by Salicornia virginica (perennial pickleweed). Two ground‐based techniques, using quadrat and line intercept sampling, and a remote sensing technique, using low altitude, high resolution, color and color infrared photographs, were applied to estimate cover in three small restoration sites. The remote technique provided an accurate and efficient means of sampling vegetation cover, but individual species could not be identified, precluding estimates of species density and distribution. Aerial photography was determined to be an effective tool for vegetation monitoring of simple (i.e., single‐species) habitat types or when species identities are not important (e.g., when vegetation is developing on a new restoration site). The efficiency associated with these vegetation sampling techniques was dependent on the scale of the assessment, with aerial photography more efficient than ground‐based sampling methods for assessing large areas. However, the inability of aerial photography to identify individual species, especially mixed‐species stands common in southern California salt marshes, limits its usefulness for monitoring restoration success. A combination of aerial photography and ground‐based methods may be the most effective means of monitoring the success of large wetland restoration projects.     

Binding of the anti-human sperm monoclonal antibody HS-11 to bull spermatozoa is correlated with fertility in vitro

The present study aimed to determine if there is bull to bull variation in the binding of the anti-human sperm monoclonal antibody (MAb) HS-11 to bull spermatozoa, and to investigate if there is any correlation between HS-11 binding to spermatozoa and in vitro fertility of the bulls tested. Semen samples of a single collection (split frozen in 0.5-ml straws) from 8 dairy bulls were used. Swim-up separated motile spermatozoa were incubated in 90-microl drops of capacitation medium (TALP+10 microg/ml heparin) at 39 degrees C, 5% CO2, 95% air. At 0, 2, 4 and 6 h of incubation HS-11 was added (1:1000 final concentration), and the MAb binding was assessed by indirect immunofluorescence assay (IIFA). The HS-11 binding was indicated by a bright green fluorescence of the sperm acrosome region. In vitro-matured, good quality bovine oocytes were randomly allocated to spermatozoa of each bull for in vitro fertilization. Sperm samples of 2 to 3 bulls were used in each trial until 4 replicates per bull were attained for IVF (n approximately 100 oocytes/bull) and IIFA experiments. Sperm capacitation status was assessed simultaneously using an egg yolk lysophosphatidylcholine- (LC) induced acrosome reaction assay. The binding of HS-11 to spermatozoa was maximum at 4 h of incubation in most (6/8) of the bull semen samples. Significant (P < 0.01) differences were observed between bulls in the binding of HS-11 to their spermatozoa (range 22 +/- 8 to 52 +/- 5%) at 4 h, but not within replicates. Similarly, variations (P < 0.05) in the cleavage rate were also seen (range 22 +/- 9 to 58 +/- 7%) between bulls. The HS-11 binding and cleavage were significantly correlated (r = 0.43; n = 32; P < 0.05). The highest percentage of spermatozoa underwent acrosome reaction in response to LC treatment at the 4-h incubation period. This and the linear relationship between HS-11 binding and the cleavage rate observed in the present study together strengthen our earlier suggestion that the binding of the monoclonal antibody HS-11 to bull spermatozoa on a time-dependent manner, may indicate capacitation changes. We conclude that 1) between-bull differences exist in HS-11 binding to spermatozoa, and in the cleavage rate, and 2) HS-11 binding to spermatozoa is correlated with fertility, as determined by the cleavage of bovine oocytes matured and fertilized in vitro.     

Prospective randomised comparison of photocoagulation and rubber band ligation in treatment of haemorrhoids.

Two hundred and sixty eight patients with haemorrhoids were allocated at random to treatment by either photocoagulation (group 1, n=141) or rubber band ligation (group 2, n=127) and followed up for one year. There was no significant difference in the symptomatic outcome of treatment between the two groups at one, four, or 12 months, irrespective of whether first or second degree haemorrhoids were treated. Side effects of treatment (bleeding or severe pain) were significantly more common after rubber band ligation (n=11) than after photocoagulation (n=2; p less than 0.01). Further outpatient treatment, however, was required significantly more often after photocoagulation (n=23) than rubber band ligation (n=6) (p greater than 0.02), and 19 patients (14 in group 1 and five in group 2; NS) subsequently had a haemorrhoidectomy. At one year 26 of 103 patients were dissatisfied after photocoagulation compared with 20 of 88 after rubber band ligation. Photocoagulation is a safe and comfortable treatment which gives long term results that are as good as those of rubber band ligation. Complications are more common after rubber band ligation, but further treatment is required more commonly after photocoagulation.