Cocoon Surface Research Articles

Characterisation of cocoon of different population of Antheraea assamensis (Lepidoptera: Saturniidae)

ABSTRACT The characterisation of cocoons is one of the most important requirements to know the economic importance of a sericigenous insect. Antheraea assamensis produces the golden muga silk, which is considered as the second most expensive silk in the world for its high quality. Although muga silk worm is a single species, it has many varieties with respect to its geographical areas. However, literary works on the most important economic traits connected to silk production of different populations of A. assamensis are very limited. Therefore, the present study has been aimed to know the cocoon efficiency and the silk quality of the different populations of the A. assamensis following the standard techniques. The study was performed after collecting the cocoon samples from 11 different regions of the North East India. The result showed that A. assamensis exhibit variation in cocoon colour along with other significant differences in the cocoon weight, shell weight, shell ratio and silk quality. The cocoons of the wild population recorded more cocoon weight, shell ratio, filament length and tenacity but at the same time due to the deposition of higher degree of calcium oxalate crystals on the cocoon surface, they were hard to reel. Based on these characters, the study recommended some stocks, which could be used for future breeding programme based on the genetic distance between the parents.

Automated quality assessment of cocoons using a smart camera based system

In this paper, the development of a novel quality assessment system for Bombyx mori L. cocoons is presented, which offers significant advantages over the conventional manual method (subjective, tests only few sample cocoons, involves health hazards) in terms of labor friendliness, accuracy, speed and running cost. This system consisted of a conditioned illumination unit, image acquisition and processing unit realized with a smart camera. The camera acquired the images of cocoons and by image processing algorithms (morphological operation, image enhancement, and ellipse fitting), quantitative measurements of size, shape and stain color were accomplished and automatically classified each cocoon into four defective categories and good cocoons. The system not only highlighted each category on camera screen but also displayed statistical information such as counts of cocoons in each category and overall defect percentage. In addition to that, the system was programmed to alert the user when the defect percentage exceeded a particular threshold value. The results showed that the system was capable of assessing 96 cocoons per second acquired within a single frame. It showed 100% accuracy on a sample size of 137 cocoons. To expose whole cocoon surface, they were rolled over a slope at a speed of eight rotations per second, while the system captured and processed the video of the whole surface. This process enabled in meeting the same level of quality assessment standard and counting accuracy as that of manually exposing the defective areas to the field of view when acquired in a single image.

Effects of Surface Hydrophobicity on Functionalization of Oleic Acid on <i>Bombyx mori</i> Silkworm Cocoons

The objective of this study is to provide a method which allows introduction of functional groups onto silk cocoon surface. Plasma irradiation is straight-forward, relatively noninvasive and requires minimal chemical reaction steps to alter surface hydrophilicity of polymeric materials. Introduction of oleic acid on pristine and air-zero irradiated silkworm (Bombyx mori) cocoons was carried out via acid-catalyzed esterification. The reaction was confirmed by ATR-FTIR spectroscopy. Functionalization of oleic acids onto silkworm cocoons favors hydrophilic surface. In addition to the acid-catalyzed esterification, amide hydrolysis takes place as a side reaction. This reaction leads to formation of hydrophilic carboxylic acids and amines. The change in hydrophilic functionalities leads to an increase in cocoon wettability as confirmed by contact angle measurements.

천잠 누에고치의 일반 성상

국내에서 생산한 천잠 누에고치의 일반 특성을 고찰한 결과 국내산 천잠 누에고치는 연두색 고치를 지으며, 층상구조를 가지고 있었다. 천잠 누에고치는 외피는 연두색이었고 내피는 흰색을 나타내어 천잠 누에고치의 색상을 나타내는 색소 성분은 외피에 존재하였다. 천잠 누에고치는 고치층의 무게는 0.528 g, 견층두께는 0.424 mm로 측정되었다. 천잠 누에고치를 구성하는 주요 아미노산은 알라닌, 글리신, 세린, 아스파르트산, 티로산, 아르기닌 순으로 나타났으며, X-선 회절분석 결과 <TEX>$2{\theta}=16.8^{\circ}$</TEX>, <TEX>$20.4^{\circ}$</TEX> 부근에서 강한 회절 피크와 <TEX>$2{\theta}=15.0^{\circ}$</TEX>, <TEX>$24.3^{\circ}$</TEX>, <TEX>$30.0^{\circ}$</TEX> 부근에서 날카로운 회절 피크를 나타내었다. 천잠 누에고치는 폭이 <TEX>$20{\mu}m$</TEX> 정도인 섬유가 적층된 구조를 가지고 있으며, 고치의 안쪽과 바깥쪽에 흰색 결정을 가지고 있었다. 천잠 누에고치의 최대 열분해 온도는 <TEX>$370^{\circ}C$</TEX> 부근이었다. 이러한 천잠 누에고치에 대한 연구 결과는 향후 천잠 누에고치를 이용한 소재 개발의 기초 자료로 활용될 수 있을 것으로 기대한다. Antheraea yamamai silkworm cocoon is considered as a natural biocompatible materials, but can not be used as medical resources due to its difficult processability. In this study, we examined the general characteristics including cocoon shell weight and structural and thermal properties of Antheraea yamamai silkworm cocoon. The cocoon shell weight and thickness of wild silkworm cocoon was 0.528 g and 0.424 mm, respectively. The cocoon has yellow-green color in outside cocoon but white in inner layer cocoon. Amino acid analysis showed that the main amino acid of Antheraea yamamai cocoon is alanine, glycine, serine, aspartic acid, tyrosine and arginine. X-ray diffractometry showed that strong diffraction peaks at <TEX>$2{\theta}=16.8^{\circ}$</TEX>, <TEX>$20.4^{\circ}$</TEX>, corresponded to <TEX>${\beta}$</TEX>-sheet structure and sharp diffraction peaks at <TEX>$2{\theta}=15.0^{\circ}$</TEX>, <TEX>$24.3^{\circ}$</TEX>, <TEX>$30.0^{\circ}$</TEX> due to the presence of calcium oxalate on cocoon surface. Antheraea yamamai cocoon was degraded at <TEX>$370^{\circ}C$</TEX>. These results might be used as basic information for development of non-textile materials using Anthereae yamamai silkworm cocoon.

Potential mode of protection of silkworm pupae from environmental stress by harboring the bacterial biofilm on the surfaces of silk cocoons.

The silkworm forms cocoon to protect its pupa that survives for months inside the cocoon without being affected by various environmental stresses. To understand the possible mode of pupal survival within the cocoon encasement, we investigate the cause that protects the cocoon. During the end of the spinning process, we have isolated different bacterial species from the cocoon surface. These are identified using molecular techniques and checked for their abilities to form biofilm in vitro. The bacteria are able to form biofilm either individually or in consortia. Of which, Bacillus and Erwinia species are prominent biofilm formers. Interestingly, these bacteria have the ability to form biofilm on the cocoon mimetic surface of the silk protein Sericin Hope that contains only sericin. The origin and the behavior of the bacteria lead us to hypothesize the possible role of biofilm layer on the cocoon surface, which provides protection from adverse environmental conditions.

Dynamics of symbiont-mediated antibiotic production reveal efficient long-term protection for beewolf offspring

BackgroundInsects have evolved a wide range of mechanisms to defend themselves and their offspring against antagonists. One of these strategies involves the utilization of antimicrobial compounds provided by symbiotic bacteria to protect the host or its nutritional resources from pathogens and parasites. In the symbiosis of the solitary digger wasp, Philanthus triangulum (Hymenoptera, Crabronidae), the bacterial symbiont ‘Candidatus Streptomyces philanthi’ defends the developing larvae against pathogens by producing a mixture of at least nine antimicrobial substances on the cocoon surface. This antibiotic cocktail inhibits the growth of a broad range of detrimental fungi and bacteria, thereby significantly enhancing the offspring’s survival probability.ResultsHere we show that the production of antimicrobial compounds by the beewolf symbionts is confined to the first two weeks after cocoon spinning, leading to a high concentration of piericidins and streptochlorin on the cocoon surface. Expression profiling of housekeeping, sporulation, and antibiotic biosynthesis genes indicates that antibiotic production coincides with morphological differentiation that enables the symbionts to survive the nutrient-limited conditions on the beewolf cocoon. The antibiotic substances remain stable on the cocoon surface for the entire duration of the beewolf’s hibernation period, demonstrating that the compounds are resistant against environmental influences.ConclusionsThe antibiotic production by the beewolf symbionts serves as a reliable protection for the wasp offspring against pathogenic microorganisms during the long and unpredictable developmental phase in the subterranean brood cells. Thus, the beewolf-Streptomyces symbiosis provides one of the rare examples of antibiotics serving as an efficient defense in the natural environment and may aid in devising new strategies for the utilization of antibiotic combination therapies in human medicine against increasingly resistant bacterial and fungal pathogens.

Mechanism of fluorescent cocoon sex identification for silkworms Bombyx mori

By using silkworms, Bombyx mori, fluorescent cocoon sex identification (FCSI) as an experimental material, direct fluorescence spectrometry of the cocoon surface indicates that the fluorescent color of silkworm cocoons is made up of two peaks of yellow and blue-purple fluorescence emission. The fluorescent difference between male and female cocoons is attributed to the differential absorption of yellow fluorescent substances by the midgut tissue of 5th instar female silkworms. Thin layer chromatography (TLC) and fluorescent spectra indicate that blue-purple fluorescent substances are composed of at least five blue-purple fluorescent pigments, and yellow fluorescent substances are made up of at least three. UV spectra and AlCl₃ color reaction show that the three fluorescent yellow pigments are flavonoids or their glycosides. Silkworm FCSI is due to selective absorption or accumulation of the yellow fluorescent pigments by the posterior midgut cells of female 5th instar larvae. The cells of the FCSI silkworm midgut, especially the cylinder intestinal cells of the posterior midgut have a component which is a yellow fluorescent pigment-specific binding protein that may be vigorously expressed in the 5th instar larvae.

A factor concerning the formation of wrinkle on the cocoon surface

A factor concerning the formation of wrinkle on the cocoon surface

Surface topology and structural integrity of the Theromyzon tessulatum (Annelida: Hirudinea: Glossiphoniidae) cocoon

Cocoons secreted by the aquatic leech Theromyzon tessulatum comprise a tubular, membranous ovoid, sealed at each end by a glue-like substance, called an operculum. Scanning electron microscopy showed surface features of the T. tessulatum cocoon that included a circuitous bulge, cups that conformed to the shape of embryos, relief folds that radiated from opercula, and asymmetric distributions of protuberances on the upper aspect of the cocoon surface. The structural integrity of the T. tessulatum cocoon was assessed after exposure to a variety of denaturing conditions (e.g., extreme heat, detergents, acids). Although both the fibrous cocoon membrane and opercula were strikingly resilient, the membrane/operculum boundary appeared to be the weakest structural component of the cocoon, consistent with its functional role as an escape hatch for juvenile leeches. The operculum itself was more sensitive to denaturation than the cocoon membrane, and thus was probably the source of a major protein component isolated from the T. tessulatum cocoon (i.e., Tcp; Theromyzon cocoon protein).

Two-dimensional ultrastructural elements lead to three-dimensional reconstruction of protuberances on the cocoon membrane of the leech, Theromyzon tessulatum

Protuberances on the cocoon surface of the leech, Theromyzon tessulatum, are roughly parallel rows of triangular prisms arranged equidistantly to each other on the outer surface of the cocoon membrane. The distance between neighboring protuberances is ∼1.6 μm, the height ∼0.5 μm and the semi-width ∼0.3 μm. The fibrillar arrangement within the protuberance maintains some elements of the helicoids found within the cocoon membrane but a high proportion of large holes disrupt the symmetry of the protuberance ultrastructure. A procedure for 3D reconstruction of the protuberance using the complementarity between the paratangential and normal sections through the cocoon is presented. Our results demonstrate that the ultrastructure of protuberances show elements of a twisted fibrillar arrangement, but the demands of filling a narrow space ruled by acute angles appears to cause a high degree of ultrastructural disorganization.

The roles of insect cocoons in cold conditions

The cocoons characteristic of the prepupal and pupal stages of many insects vary widely in size, durability, structure, shape and colour, as well as in other features such as orientation and attachment to the substrate. In some species they vary seasonally. Most cocoons provide little direct insulation, although they may reduce the rate at which temperature changes, but many provide the mechanical protection required for overwintering beneath insulating substrates such as soil and snow. The cocoons of some terrestrial species prevent inoculative freezing by isolating the integument from ice crystals on the cocoon surface or its surroundings. In some aquatic species, cocoons appear to limit damage by providing mechanical protection during the freezing of surrounding water. Some cocoons help in the acquisition of solar heat: dark structures are especially effective because dark pigments absorb heat, and surrounding layers trap this heat. Insects are immobilized when it is cold and so cannot move in response to environmental threats, and protective cocoons made for winter tend to be more robust than their summer counterparts. Such cocoons protect against abrasion of the waterproof layer of the cuticle. In some species, robust cocoons or complex structures impede natural enemies. Cocoon silk has anti-bacterial and anti-fungal actions. Other cocoons are more or less waterproof. These and other features withstand simultaneous constraints in addition to cold. Therefore, cocoons enhance survival during cold conditions in many species. However, this conclusion is based on fragmentary evidence, and there has been relatively little explicit examination of the roles of cocoons during winter. Therefore, specific work is required to assess resistance to or enhancement of inoculative freezing, resistance to penetration by natural enemies and water, the roles of particular cocoon silks and silk constituents, and the quantitative contributions of cocoons to winter survival in nature.

On the escape of cosmic rays from radio galaxy cocoons

The escape rate of cosmic ray (CR) particles from radio galaxy cocoons is a problem of high astrophysical relevance: e.g. if CR electrons are stored for long times in the dilute relativistic medium filling the radio cocoons ( radio plasma in the following) they are protected against Coulomb losses and thus are able to produce a significant non-thermal Comptonisation signature on the CMB. On the other hand, CR protons and positrons which leak out of radio plasma can interact with the ambient medium, leading to characteristic gamma ray radiation by pion decay and pair annihilation. In order better understand such problems a model for the escape of CR particles from radio galaxy cocoons is presented here. It is assumed that the radio cocoon is poorly magnetically connected to the environment. An extreme case of this kind is an insulating boundary layer of magnetic fields, which can efficiently suppress particle escape. More likely, magnetic field lines are less organised and allow the transport of CR particles from the source interior to the surface region. For such a scenario two transport regimes are analysed: diffusion of particles along inter-phase magnetic flux tubes (leaving the cocoon) and cross field transport of particles in flux tubes touching the cocoon surface. The cross field diffusion is likely the dominate escape path, unless a significant fraction of the surface is magnetically connected to the environment. Major cluster merger should strongly enhance the particle escape by two complementary mechanisms. i) The merger shock waves shred radio cocoons into filamentary structures, allowing the CRs to easily reach the radio plasma boundary due to the changed morphology. ii) Also efficient particle losses can be expected for radio cocoons not compressed in shock waves. There, for a short period after the sudden injection of large scale turbulence, the (anomalous) cross field diffusion can be enhanced by several orders of magnitude. This lasts until the turbulent energy cascade has reached the microscopic scales, which determine the value of the microscopic diffusion coefficients.

Physiology of cold hardiness in earthworms

Abstract Physiological, biochemical and behavioral mechanisms involved in the winter survival of earthworms and earthworm cocoons are reviewed. Overwintering strategies of cold hardy invertebrates are commonly divided into two groups. In freeze-avoiding animals, ice formation in the tissues is lethal and winter survival is dependent on prolonged and extensive supercooling. Freeze-tolerant animals tolerate extracellular freezing up to a certain fraction of the body water. Hatched earthworms belong to the first group, having a behaviorally-based strategy, escaping frost in the soil by migration. The cold hardiness mechanism of earthworm cocoons is based on a protective dehydration of cocoons occurring when cocoons are exposed to subzero temperatures in a frozen environment. Due to the lower vapour pressure of ice compared to supercooled water at a given temperature, water evaporates from the cocoon surface and condenses onto ice in the surroundings. Dehydration of cocoons continues until vapour pressure equilibrium between cocoon fluids and surrounding ice is attained. At equilibrium the cocoons cannot freeze since the melting point of cocoon fluids equals ambient temperature. Because the melting point of cocoon fluids is high, −0.2 to −0.4°C, the cocoons lose substantial amounts of water, even at mild freezing exposures. As a response to dehydration the embryos of the cocoons accumulate a polyol, probably sorbitol, which may prevent deleterious effects of the extensive water loss coupled with vapour equilibration. Since dehydration is a key event when earthworm cocoons are exposed to low temperatures it is likely that tolerance to drought is important for cold survival. Substantial support for this hypothesis has been found in Dendrobaena octaedra which is far more tolerant to drought and cold than other investigated species. It is suggested that the described “protective dehydration mechanism” of cold hardiness should be considered in cold hardiness studies of other soil animals with high cuticular evaporation rates.

Structure of the cocoon of the neotropical bumblebee Bombus atratus Franklin

The cocoon of Bombus atratus was studied using cytochemical methods and polarization microscopy. The aims were to investigate the components of the cocoon and to establish their stereoarrangement in the cocoon wall. Filamentous layers assumed to be composed of the structural proteins produced by the silk glands appear to make up the framework of the whole structure. They are arranged nearly parallel to the cocoon's surface and depict some reorientation of their protein macromolecules when compared with the situation found in the lumen of the silk glands. These layers enclose masses of pollen grain remnants excreted by the larvae as it spun the cocoon. The pollen grains are stuck together by a mucus which has the cytochemical and some of the anisotropic properties of the secretion discharged by the Malpighian tubules of the larva. Mucous layers, assumed to be produced by the silk glands, cover the cocoon externally. Eventually they also appear associated with the inner filamentous layers. Urate crystal units, sometimes containing acid glycosaminoglycans in their cores, occur in the cocoon wall and come from the Malpighian tubules. The cocoon of B. atratus is not impregnated with calcium.

A factor concerning the formation of wrinkle on the cocoon surface

A factor concerning the formation of wrinkle on the cocoon surface

A factor concerning the formation of wrinkle on the cocoon surface

A factor concerning the formation of wrinkle on the cocoon surface