The ultrastructure and calcification of the scales of Tilapia mossambica (Peters)

Summary The scales of Tilapia are surrounded by an envelope of scleroblasts responsible for the production of layers of collagen that constitute the bulk of the scale. The scleroblasts adjoining the lateral face of the oldest scale region gradually atrophy. New collagen layers are deposited against the inner face of the scale, the adjoining scleroblasts showing evidence of high metabolic activity. Calcification occurs by inotropic deposition of crystals alongside the fibres. There is no sharp demarcation between calcified and non-calcified scale regions, a calcification front gradually moving towards newly formed collagen layers. It is felt that fish scales should be considered as calcified derivatives of dermal collagen layers.     

Mechanical design of polypterid fish integument for energy storage during recoil aspiration

Polypterid fishes ventilate their lungs by recoil aspiration. Active exhalation compresses the bony scale jacket; inhalation occurs when the scale jacket recoils to its original shape. Exhalation and loading of the integument are powered by contraction of striated muscle in the lung walls. The integument of polypterid fishes consists of interlocking rhomboid scales held together by collagen fibre strands. The scales imbricate with bevelled edges, so that when the fish is at rest, its integument is circular in cross-section and the overlapping scale edges are parallel. During exhalation, the hemicircular shape of the ventral integument is deformed, and the scales rotate slightly. As the overlapping scale edges become non parallel, the scales act as tiny levers to stretch the collagen fibres between them. When the fish opens its glottis to inhale, the stretched collagen fibres return to their rest lengths and pull the scale jacket back into a circular shape, sucking air into the lungs. Thus, despite the deformation of the integument as a whole in compression, strain energy is stored in tensile elements.     

Evidence of denticles and attachment fibres in the superficial layer of scales in two fishes: Carassius auratus and Cyprinus carpio (Cyprinidae, Teleostei)

An attempt is made to clarify the mechanisms of the scale anchorage in two Cyprinidae, the goldfish and the carp. Scanning and transmission electron microscope investigations
revealed the presence of two different structures, denticles and collagen fibre bundles involved in the anchoring processes. These strucures are located on the upper part of the
scales. Denticles form minute processes on the circuli of the anterior areas of the scales. Collagen fibre bundles arise from the superficial layer connecting the scale to the overlying dermis. These fibre bundles show structural similarities with the Sharpey's fibres and are named Sharpey-fibre-like bundles. Such fibres of attachment, not previously reported, can be considered as usual anchoring structures in fish scales.     

Structure and composition of teleost scales from snakehead Channa argus (Cantor) (Perciformes: Channidae)

The structure of teleost scales from snakehead Channa argus was investigated using thermogravimetric analysis (TG), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive analysis of X-rays (EDAX), Fourier transform infra-red spectroscopy (FTIR) and X-ray diffraction (XRD). Thermal treatment of fish scales indicates that the fibrillary plate is partially calcified. SEM shows two kinds of scale denticles, arranged along the circuli in the anterior field and the lateral fields, respectively. TEM indicates the stratum laxum with abundant fibrils, chromatophores and capillary blood vessels within the scale covering, and shows the fibrillary plate as an 'orthogonal plywood structure' of stratified lamellae, consisting of 80–100 nm diameter collagen fibres co-aligned in individual lamellae and alternated by c. 90° of the fibre alignment between adjacent lamellae. EDAX, FTIR and XRD show that the mineral phase of the scales is a carbonated hydroxyapatite with a Ca:P molar ratio of 1·85.     

鲤鱼鱼鳞在盐酸脱钙过程中的变化

鱼鳞主要由表层的钙化层和内部的胶原纤维层构成,为提取鱼鳞胶原蛋白,首先要脱除鱼鳞表面的钙化层。本文主要研究鲤鱼鱼鳞在盐酸脱钙过程中的变化。鱼鳞在盐酸脱钙过程中外部形态首先发生变化,钙化层溶解变薄,鱼鳞的柔软性增加。随着脱钙过程的进行,盐酸逐渐渗透到鱼鳞内部。经过盐酸处理后鱼鳞的力学性质发生很大的改变,断裂强度大大降低,只有原始鱼鳞的1/3~1/4。说明鱼鳞中以羟基磷灰石为主要成分的无机物层对保护鱼鳞起到了很大的作用,也为鱼鳞坚韧的质构发挥了重要的作用。     

Threatened fishes of the world: <Emphasis Type="Italic">Chalcalburnus tarichi</Emphasis> (Pallas 1811) (Cyprinidae) living in the highly alkaline Lake Van,Turkey

A member of the Cyprinidae family, the Chalcalburnus tarichi is a fish species that only inhabits the Lake Van Basin. The Lake Van represents an interesting ecosystem in the world, known as the biggest soda lake in the world, in that its water is highly alkaline with a pH of 9.8. C. tarichi has bright-silver color, its back is grayish green, and the abdominal region is silver. Its body is covered with small scales, and its eyes are large. It feeds on phyto and zooplanktons. Its average life span is 7 years, and the fish reaches reproductive maturity at 3 years old. C. tarichi is an diadrom fish that lives in the lake, but during the reproduction period it immigrates to the surrounding freshwater rivers returning after the reproduction period of April–July. In the past, pearl mullet was an attractive fresh fish for the local people and was easily caught during the spawning migration, resulting in over-fishing. The species was one of the highly endangered animals of Turkey before conservation studies, some 10 years ago, have started. At present, illegal fishing activities declined, although some locals are continuing to fish during the spawning season.     

Osteodentine and vascular osteodentine of Anarhichas lupus (L.)

Summary TEM, SEM and X-ray diffraction analysis demonstrate the heterogeneity of the dentinal tissue of Anarhichas lupus, a vascular osteodentine. The disordered aspect of collagen fibres, incompletely mineralized (the periodical striation being still visible), explains the scattered distribution of crystallites since they are responsible for their arrangement. The low degree of mineralization revealed by the visible collagen striation is confirmed by X-ray diffraction analysis (the crystallinity of vascular osteodentine being much lower than that of the peripheral dental tissue) as well as by high resolution TEM, since no lattice planes could be observed. Osteodentine, supporting bone and proper bone have in common a mineral phase, more or less organized, different from the apatite system.The authors thank Mireille Cottrel-Gengoux for her technical assistance     

Collagen Extract from Marine Finfish Scales as a Potential Mosquito Larvicide

Collagen is a peptide being utilized in medical, health care, nutrient and decorative industry. Marine fish scales are one of the good sources of collagen, which is extracted using the advanced enzymatic digestion method. Scales of Sardinella longiceps (Oil Sardine) have a high proportion of collagen. This product is well absorbed with broad adaptive values that encourage the inclusion of nutriments. In this paper, we have performed the isolation and characterization of collagen from S. longiceps fish scales. The unnecessary proteins on the surface of fish scales was removed by demineralization process. The fish scale collagen was extracted in two different methods: acid (acetic acid) and enzymatic (pepsin) technique. The molecular mass of the extracted collagen was determined using sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The absorption spectra of the extracted collagen was measured to estimate its amino acid (tyrosine) content. Fourier transform infrared (FTIR) spectrum showed the existence of bands corresponding to the collagen extracted from S. longiceps fish scale and the crystallinity of extracted collagen was obtained using X-ray diffraction (XRD) analysis. The morphological micrograph was also analyzed by scanning electron microscope (SEM). The anti-larval effect of the collagen extract was determined using mosquito larvae of Aedes aegypti (Ae. aegypti) and the activity was statistically significant.     

A new species of the deepwater cardinalfishEpigonus (Perciformes: Epigonidae) from the Galápagos Islands

A new species of deepwater cardinal fish,Epigonus merleni, is described from a specimen found floating at the sea surface as a result of the eruption of Fernandina Volcano, Isla Fernandina, Galápagos Islands. It differs from all knownEpigonus in having the greatest number of lateral line scales (57) and the fewest gill rakers (17), as well as in several other characters.     

Seasonal changes in light transmission by bud scales of spruce and pine

A bundle of optical fibres and a photometer were used to measure light transmission through bud scales of Norway spruce [Picea abies (L.) Karst.] and Scots pine (Pinus silvestris L.). Percentage transmission increases with wavelength from none below 480 nm to 3% the far-red. Transmission of all wavebands measured was lowest in late summer and winter and highest in the autumn and spring. For most of the year in pine, and only from July to September in spruce, there is a depression of red light (660–670 nm) transmission. This affects the ratio of 660/730 nm light penetrating the apical domes. This ratio is lowest in July and August, at the time of initiation of female strobili. The seasonal variation in transmission of light by bud scales is discussed in relation to the possible consequences for the control of flowering.     

Have introduced fish initiated piscivory among the long-fingered bat?

During the winter of 2003–2004 feces were collected from a winter colony of the long-fingered bat (Myotis capaccinii) in the Hazorea cave (north-west Israel). Of the 1913 feces that were examined, 234 contained scales of Gambusia affinis – a small fish that had been introduced to Israel around 1920 in order to control mosquito larvae. The remains of spiders and five insect orders were also represented in the feces. This is the first report of a piscivorous bat in the Middle East and the first finding of fish remains in the feces of M. capaccinii. The findings show that in the north of Israel this species does not hibernate but remains active throughout the winter. It appears that the consumption of G. affinis reflects a change in the diet of these bats from insectivory to semi-piscivory.     

Structure of the dermal scales in gymnophiona (Amphibia)

Histology and cytology of dermal scales of the gymnophionans Ichthyophis kohtaoensis and Hypogeophis rostratus reveal their structure and the nature of their mineralization. Dermal scales are small flat disks set in pockets in the transverse ridges of the skin. Each pocket contains several scales of various sizes. A ring of “hypomineralization” of varying diameter may occur on scales of a particular dermal pocket but bears no relation to the diameter of these scales. Three different layers form the scales and are seen on sections perpendicular to the surface. The cells of the basal layer lie deepest. Each of the two or three more superficial fibrous layers is composed of bundles of fibres that are oriented in parallel. The orientation varies among layers. The striation of the fiber scales has a periodicity comparable to that of the surrounding dermal fibers. Squamulae form a discontinuous layer on the scale surface and are the only mineralized part of the scale. The minerals are deposited both on the collagen fibers passing from the fibrous layers into the squamulae, and in the interfibrillar spaces. Spherical concretions, either isolated or coalescent, reaching up to 1 μm, are found on the surface of the squamulae. The dermal scales of Gymnophiona present some analogies with those of evolved bony fishes. Their characteristics could make them an original model for the study of mineralization.     

Two new soldierfishes (Beryciformes: Holocentridae:Myripristis) from Japan

Two species of the holocentrid fish genusMyripristis are described as new from Japan, both with a single pair of tooth patches outside the gape at tip of lower jaw, the third anal spine longer than the fourth, and 28–29 lateral-line scales:M. kochiensis from Kashiwa-jima, Kochi Prefecture, previously misidentified asM. murdjan, is distinct in having small scales in axil of pectoral fins, 32–36 gill rakers, interorbital space 4.45–5.1 in head, and lower jaw not strongly projecting when mouth closed;M. greenfieldi, from the Ryukyu Islands and Ogasawara Islands to Kochi Prefecture, previously misidentified asM. woodsi andM. randalli, is distinct in lacking scales in the pectoral axil, having 35–52 cteni on largest body scales, 43–47 gill rakers, and longest dorsal spine 2.0–2.25 in head.     

Light conditions inside developing buds affect floral induction

Buds of Pinus sylvestris L. and Picea abies (L.) Karst. were pierced with optical fibres allowing natural light to the vicinity of apical domes. Induction of female strobiles was achieved. Since bud scales absorb more red than far-red light, the treatment may have increased the far-red light absorbing form of phytochrome.Abbreviations Pfr far-red light absorbing form of phytochrome     

Validation of scale‐age determination in European grayling Thymallus thymallus using tag‐recapture analysis

To validate age determination from scales in European grayling Thymallus thymallus, the scale‐read age of fish was compared with the true age obtained by tag‐recapture analysis. A total of 3997 individuals were tagged with visible implant tags and passive integrated transponder (PIT) tags in the River Wylye, south‐west England during 1999–2007. Annual repeat surveys were undertaken and collected scales read without prior knowledge of tag‐recapture age. Accuracy of fish ageing by scales was highest in 1 and 2 year‐old fish but decreased in older fish. In later life stages (>4 years old), underestimation of age occurred and the error in reading scales rose to 51·9% in 5 year‐old fish. Age assigned from scales underestimated the tag‐recapture assigned age by as much as 3 years. This study suggests that use of scales is an appropriate method to age a short‐lived population of T. thymallus inhabiting productive lotic systems. The underestimation of age in older fish, however, needs to be considered in the management of fish stocks because it may lead to undesirable exploitation of population.     

Parasite species coexistence and limiting similarity: a multiscale look at phylogenetic,functional and reproductive distances

The factors that control biodiversity have been the focus of numerous recent investigations; these include species interactions, speciation, environmental gradients and heterogeneity, all of these operating differently at each observation scale. We used a null model to examine the influence of two forces shaping the community structure of Dactylogyrus species parasitic on roach (Rutilus rutilus) gills: interspecific competition that might prevent the coexistence of the most similar species and environmental filters that might result in the most similar species coexisting together. The study was carried out on two sets of fish from two different localities in the Morava river basin (Czech Republic) to evaluate the consistency of the results across host populations, and at three different scales of observation to test for the scale dependence of assembly rules. In decreasing order, from largest to smallest, the three spatial scales investigated were: the individual fish, the individual gill arch and individual sections of each gill arch. The similarity between pairs of parasite species was measured using three different criteria: (1) phylogeny, (2) quantitative functional traits consisting of parasite size and morphometric measurements of the attachment organ’s sclerotized parts and (3) qualitative attributes of reproductive organs. First, our study reveals a strong conservatism of ecological characters for the nine Dactylogyrus parasite species, in particular regarding the attributes of their copulatory organs. Second, our study did not find any limitation of similarity among coexisting Dactylogyrus species due to interspecific competition, irrespective of the scale and the similarity measures considered. Conversely, our results support the niche filtering hypothesis, preventing the co-occurrence of species too dissimilar from one another. This process is particularly apparent at the scale of the individual fish and for functional traits associated with the hard parts of the parasites’ attachment organs. In both localities, the Dactylogyrus species that occur on the same fish individuals tend to have similar values for the haptor dimensions. Our study supports previous studies on monogenean parasite communities indicating a weak influence of competition as a structuring force, but it goes a step further by identifying environmental filtering as a key process shaping these communities.     

Structural and mechanistic insights into collagen degradation by a bacterial collagenolytic serine protease in the subtilisin family

A number of proteases in the subtilisin family derived from environmental or pathogenic microorganisms have been reported to be collagenolytic serine proteases. However, their collagen degradation mechanisms remain unclear. Here, the degradation mechanism of type I collagen fibres by the S8 collagenolytic protease MCP‐01, from Pseudoalteromonas sp. SM9913, was studied. Atomic force microscopy observation and biochemical analysis confirmed that MCP‐01 progressively released single fibrils from collagen fibres and released collagen monomers from fibrils mainly by hydrolysing proteoglycans and telopeptides in the collagen fibres. Structural and mutational analyses indicated that an enlarged substrate‐binding pocket, mainly composed of loops 7, 9 and 11, is necessary for collagen recognition and that the acidic and aromatic residues on these loops form a negatively charged, hydrophobic environment for collagen binding. MCP‐01 displayed a non‐strict preference for peptide bonds with Pro or basic residues at the P1 site and/or Gly at the P1’ site in collagen. His211 is a key residue for the P1‐basic‐residue preference of MCP‐01. Our study gives structural and mechanistic insights into collagen degradation of the S8 collagenolytic protease, which is helpful in developing therapeutics for diseases with S8 collagenolytic proteases as pathogenic factors and in studying environmental organic nitrogen degradation mechanisms.     

On the purported presence of fossilized collagen fibres in an ichthyosaur and a theropod dinosaur

Since the discovery of exceptionally preserved theropod dinosaurs with soft tissues in China in the 1990s, there has been much debate about the nature of filamentous structures observed in some specimens. Sinosauropteryx was the first non‐avian theropod to be described with these structures, and remains one of the most studied examples. Despite a general consensus that the structures represent feathers or feather homologues, a few identify them as degraded collagen fibres derived from the skin. This latter view has been based on observations of low‐quality images of Sinosauropteryx, as well as the suggestion that because superficially similar structures are seen in Jurassic ichthyosaurs they cannot represent feathers. Here, we highlight issues with the evidence put forward in support of this view, showing that integumentary structures have been misinterpreted based on sedimentary features and preparation marks, and that these errors have led to incorrect conclusions being drawn about the existence of collagen in Sinosauropteryx and the ichthyosaur Stenopterygius. We find that there is no evidence to support the idea that the integumentary structures seen in the two taxa are collagen fibres, and confirm that the most parsimonious interpretation of fossilized structures that look like feather homologues in Sinosauropteryx is that they are indeed the remains of feather homologues.     

Peptide-based fibrous biomaterials: Some things old, new and borrowed

Bioinspired fibrous materials that span the nano-to-meso scales have potentially broad applications in nanobiotechnology; for instance, as scaffolds in 3D cell culture and tissue engineering, and as templates for the assembly of other polymer and inorganic materials. The field is burgeoning, and this review is necessarily focused. It centres on recent developments in the design of peptide-based fibres and particularly those using the alpha-helix and the collagen triple helix as building blocks for self-assembly. Advances include new designs in both categories, the assembly of more-complex topologies using fibres themselves as building blocks, and the decoration of the assembled materials with functional moieties.     

A new cuticle scale hydrolysing protease from Beauveria brongniartii

From a screening for the production of new proteases specific for cuticle scales, Beauveria brongniartii was selected producing an alkaline Ca⁺⁺ dependent protease. The purified had a molecular weight of 27 kDa and a pI value of 8.0. Substrate specificities of model substrates (wool with partially removed cuticles treated with SDS) were analyzed by protein release, dissolved organic carbon (DOC) and nitrogen analysis. The C/N ratio of released material turned out to be a good parameter to determine the site of action of proteases on fibres. Compared to other enzymes, the fungal protease preferentially hydrolyzed cuticle scales and has thus a potential for anti-shrinking pre-treatment of wool fabrics.