Gumfooted lines in black widow cobwebs and the mechanical properties of spider capture silk

Orb-weaving spiders produce webs using two types of silk that have radically different mechanical properties. The dragline silk used to construct the supporting frame and radii of the web is stiff and as strong as steel, while the capture spiral is much weaker but more than ten times as extensible. This remarkable divergence in mechanical properties has been attributed to the aqueous glue that coats the capture spiral, which is thought to decrease capture spiral stiffness and increase its extensibility. However, discerning the effect of the aqueous glue on fiber performance is complicated because dragline silk and the capture spiral are assembled from different proteins, which may also affect mechanical performance. Here, we use the sticky gumfooted lines of black widow cobwebs to test the effect of the addition of aqueous glue on the mechanical properties of dragline silk. We also surveyed orb-webs spun by a broad range of species for bundles of looped silk. Such bundles, termed windlasses, have been thought to increase capture spiral extensibility by "paying out" additional lengths of silk. Our results suggest that neither plasticization of silk by aqueous glue nor excess silk in windlasses can by themselves account for the remarkable extensibility of orb-weaver capture silk compared to other spider silks. This argues that the unique amino acid motifs of the flagelliform fibroins that constitute the core of the capture spiral play an essential role in capture silk's extreme extensibility.

Identification and morphological characteristics of dental neonatal line in sika deer (Cervus nippon)

The dental neonatal line of the sika deer (Cervus nippon) was identified experimentally using chronological labeling methods. In the enamel, prominent dark lines were observed under transmitted light, and the number of increments between the dark line and labeling line was almost consistent with the day-age at the time of labeling injection. Therefore, we identified the dark line as the enamel neonatal line. In the dentin, the bright line was observed under polarized light. Since the bright line corresponded to the enamel neonatal line, we recognized the bright line as the dentin neonatal line. Neonatal lines intersected with the enamel-dentin junction at approximately one-third cervical in the first molar. Using these features, it would make possible to distinguish the neonatal line in wild sika deer.

Dental Incremental Lines in Sika Deer (Cervus nippon); Polarized Light and Fluorescence Microscopy of Ground Sections

Periodic growth incremental lines are found universally in dental hard tissues. This periodicity theoretically allows for estimation of age, even in days, which would be useful in studies of wild animals. In the present study, enamel and dentin increments of the sika deer (Cervus nippon) were observed in ground sections with a polarized light microscope, and their periodicity was examined by the use of a chronological labeling method with fluorochromes. Enamel increments occurred at a mean interval of 10.6 (SD=1.5) microm, and mean spacing of dentin increments was 17.3 (SD=1.8) microm. Fluorochromic marking revealed that incremental lines form each day in enamel and almost every second day in dentin. The fluorescence-labeled lines suggest that enamel formation of the first molar is complete by the age of 5 months. Due to its longer interval of incremental lines and longer term of formation, we conclude that dentin is more suitable than enamel for day-age estimation in sika deer. Experimental confirmation of incremental growth periodicity in various species can improve the reliability of use of tooth increments for age estimation and life history reconstruction.

Changes in Proportion of Canine Urinary Calculi Composed of Calcium Oxalate or Struvite in Specimens Analyzed from 1981 through 2001

The objective of this report was to characterize 20-year changes in proportion of calcium oxalate (CaOx) calculi and struvite calculi in dogs, and associations with breed, age, and sex. In this retrospective study, results of analysis of urinary calculi from dogs were reviewed for specimens received between July 1, 1981, and December 31, 2001. Breed, sex, age, year of submission of the specimen, and mineral type(s) were analyzed statistically. CaOx or Struvite or both were contained in 18,966 of 20,884 (91%) specimens. For both sexes, a 20-year statistically significant increase was observed in the proportion of calculus specimens that contained CaOx. The increase in this proportion was greater in females (1% to 31%) than in males (18% to 82%). From 1998 to 2001, when proportions may have plateaued, the odds of specimens containing CaOx were markedly higher in 18 breeds, markedly lower in 5 breeds, and not significantly different in 13 breeds compared with crossbreds. For both sexes, a 20-year statistically significant decrease was observed in the proportion of calculus specimens that contained struvite. This decrease in proportion was greater for males (79-16%) than for females (97-68%). From 1998 to 2001, when proportions plateaued, the odds of calculi containing struvite were markedly lower in 20 breeds, markedly higher in 1 breed, and not significantly different in 15 breeds when compared with crossbreds. Breed, age, and sex were associated statistically with CaOx or struvite urolithiasis. In conclusion, there appears to have been a long-term increase in the proportion of specimens of canine urinary calculi that contain CaOx as well as a long-term decrease in the proportion of specimens of calculi that contain struvite for both male and female dogs. The rate of change appeared to begin leveling off in the period 1998 to 2001. The recent proportion of dogs with either CaOx- or struvite-associated urolithiasis may depend on breed, age, and sex, and on interactions among these 3 factors.

The anatomy of the oesophagus, stomach and intestine in common wolffish (Anarhichas lupus L.): a basis for diagnostic work and research

The alimentary canal of laboratory-reared common wolffish (Anarhichas lupus L.) was studied using light and electron microscopy. In the oesophagus, a simple columnar microvillous epithelium with transport characteristics was observed in addition to the main striated squamous epithelium. An osmoregulatory function is proposed for the simple columnar epithelium, which was supported by wide, thin-walled vessels. In the stomach, a separate type of neck cells was observed leading into the acinar gastric glands, which morphologically consist of one cell type: chief cells. The intestine was divided into a proximal and distal segment by an intestinal valve. Pyloric caeca were not present. We propose that shallow, crypt-like structures in the intestinal mucosa are the sites of epithelial-cell proliferation in juveniles and adults. The length of microvilli decreased from approximately 4 microns in the cranial part of the proximal intestine, to 1.5 microns in the distal intestine. In the distal intestine, rod-shaped bacteria were observed between microvilli. An extensive system of thin-walled vessels was observed in the submucosa of juvenile and adult wolffish stomach and intestine. Eosinophilic granular cells were numerous in the perivascular connective tissue in the gastric and intestinal submucosa of adults and juveniles, but were not observed in larvae.

Systemic kappaAL amyloidosis associated with bovine leukocyte adhesion deficiency

Histopathologic and immunohistochemical examinations were conducted on a 5-year-old Holstein-Friesian cow with systemic kappaAL amyloidosis associated with bovine leukocyte adhesion deficiency. Amyloid deposits were present in the perivascular and intercellular spaces of the visceral organs, such as the liver, kidneys, pancreas, adrenal glands, and upper alimentary tract. Amyloid was stained positively with Congo red with or without 5% potassium permanganate pretreatment and had green birefringence observed under polarized light. Immunohistochemically, amyloid reacted strongly against anti-bovine IgG (H+L) and anti-bovine kappa-light chain and reacted weakly against bovine X-light chain antibodies but was negative for anti-human amyloid AA antibody. This is the first description of AL amyloidosis immunohistochemically related to immunoglobulin kappa-light chains of precursor protein in cattle.

Localized amyloidosis in canine mammary tumors

Histopathologic and immunohistochemical examinations were performed on localized amyloidosis associated with mammary tumors in two dogs. These tumors were identified as adenoma and adenocarcinoma. An acellular, amorphous pale eosinophilic material (amyloid) was observed in the lumina of acini lined by neoplastic cells and in the stroma of the tumors. Concentrically laminated pale eosinophilic bodies (corpora amylacea) were also found in the lumina of the acini. Amyloid and corpora amylacea stained positively with Congo red with and without 5% potassium permanganate pretreatment and revealed a green birefringence under polarized light. Corpora amylacea showed an occasional Maltese-cross pattern. Immunohistochemically, amyloid and corpora amylacea usually stained positively with anti-bovine alpha-casein antibody but negatively with anti-human amyloid AA, anti-bovine kappa-light and lambda-light chains, anti-human lactoferrin, anti-human transferrin, anti-human secretory component, and anti-human polyglucosan antibodies. These findings suggested that the amyloid deposition in these canine mammary tumors was related to lactating casein.

Oxalate-producing pulmonary aspergillosis in an alpaca

An aging lactating alpaca was presented in sternal recumbency. Although bright and alert, she did not respond to symptomatic treatment and was euthanized 5 weeks after initial presentation. Gross postmortem examination revealed purulent material in the pulmonary airways. Histologic examination of the lungs revealed an extensive pyogranulomatous pneumonia with bronchiectasis. There were abundant fungal hyphae and high numbers of associated oxalate crystals, which were presumed to have been produced by the fungus. Low numbers of yeast cells were also present. Microbiological culture of tissues on horse blood agar and Sabouraud's agar identified the fungus to be Aspergillus niger. There was also moderate growth of Candida albicans. Calcium oxalate crystals in cytologic and histologic preparations can suggest an underlying Aspergillus infection. This is the first reported veterinary case of pneumonia due to Aspergillus niger infection and the associated production of oxalate crystals.

Pulmonary histiocytosis in tree shrews (Tupaia belangeri)

Granulomatous lesions similar to those of pulmonary histiocytosis in rats developed spontaneously in the lungs of captive tree shrews. Incidence peaked in 3-year-old tree shrews. Sex dependency was not observed, and development of the granulomas was unrelated to experimental procedures because the lesions were observed in animals from the breeding stock as well. The granulomas consisted of amorphous material, foam cells, and a few foreign body-type multinuclear giant cells; they also contained acicular clefts, often with some fibrous material. Alveolar septa within and adjacent to the granulomas were thickened in most instances, but did not contain inflammatory cells in appreciable numbers or amyloid. Only traces of cholesterol and calcium were detected in the amorphous material; neutral fat was stored in the foam cells and the amorphous masses. Fibers without birefringency were documented by polarization and scanning electron microscopy in the vicinity of granulomas, which in energy-dispersive X-ray microanalysis consisted mostly of calcium, but lacked silicon.

Case of calcifying epithelial odontogenic tumour in a dog

A 12-year-old male shih tzu dog was diagnosed as having a calcifying epithelial odontogenic tumour. One and a half years prior to presentation, a mass was noticed on the right mandible by the owners. Radiography revealed irregular, faintly radiopaque material within the tumour. A right hemimandibulectomy was performed, based on the clinical diagnosis of osteosarcoma. Histopathological evaluation of the mandibular mass showed that it was composed of a polyhedral odontogenic epithelial cell nest, fibrous stroma, homogeneous eosinophilic material and rounded calcifying material. The eosinophilic material was visualised by staining with Congo red, and observed under green birefringence by polarisation microscopy. Although the tumour had not recurred 12 months after surgery, the dog was euthanased because of aspiratic pharyngitis. The literature on the clinical behaviour of calcifying epithelial odontogenic tumours in dogs and cats is reviewed.

Ultrastructure and mineral composition of urinary calculi from horses

Urinary calculi from 17 horses with urolithiasis were examined to study their mineral content and ultrastructure. Among the analytic methods used were X-ray diffractometry, scanning electron microscopy, and electron microprobe analysis. The calculi initially were observed by use of a stereoscopic dissecting microscope and generally were found to have nodular surfaces surrounding a banded or granular-to-chalky interior. Observation by scanning electron microscopy revealed an intricate pattern of irregularly concentric, fine bands and spherules. These had a round, finely banded, globular texture formed by precipitation of ultrafine-grained radiating crystals. The original pore spaces (ie, between spherules, between bands and spherules, or between crystal generations) could be observed as primary porosity. Precipitation and dissolution of these urinary calculi were observed to be spontaneous processes, which can occur simultaneously within an individual calculus. Another prominent feature of the ultrastructure was secondary porosity (spontaneous dissolution) which, in its incipient stages, appeared to be site-selective (ie, some bands appeared to be more susceptible to development of pinpoint porosity). Textures indicative of dissolution were observed not only on the calculus surface, but within the calculus interior as well. Areas that had more advanced stages of dissolution, resulting in increased secondary porosity, also were observed. All 17 samples of the study were found to be composed of calcium carbonate in the form of the mineral calcite, although minor quantities of 2 other polymorphs of calcium carbonate, minerals vaterite and aragonite, also were encountered. Vaterite was observed in 5 of the samples, whereas aragonite was found in 1 sample. Strontium and sulfur were observed as trace elements in 3 of the calculi, whereas magnesium was present in all calculi. Magnesium was observed to substitute for calcium within the calcite crystal lattice in larger quantities than those of strontium or sulfur. Magnesium K alpha X-ray dot maps generated by use of an electron microprobe analyzer indicated that the distribution pattern of magnesium appeared to closely follow layer-by-layer growth of the calculus. Magnesium distribution also appeared to be related to porosity development. In samples where preferential dissolution was observed, the more porous areas had higher magnesium content. Quantitative chemical analyses, using the electron microprobe analyzer, confirmed these observations. Association of the magnesium distribution pattern to the primary growth texture of the calculus indicated that magnesium content of the calculus varied during the formation process. This also indicated that changes in urine chemical analytes may be reflected in composition of the calculi formed.(ABSTRACT TRUNCATED AT 400 WORDS)