The cocoon spinning behaviour of the chinese oak silkworm, Antheraea pernyi

The cocoon of Antheraea pernyi is constructed in four successive phases, as resolved through movement recordings and time-lapse cinematography and cinefluorography: (1) scaffolding and peduncle (9·2 hr), (2) outer cocoon (13·9 hr), (3) cocoon impregnation (0·7 hr), and (4) inner cocoon (26·9 hr). The caterpillar reverses spinning direction at frequencies characteristic for each phase. The number of cycles (360-degree turns) within a phase is relatively constant from individual to individual, although the length of phase two varies seasonally. During cocoon impregnation the larva executes turns in rapid succession, ensuring the even distribution of a hindgut exudate which coats the cocoon with crystals and speeds tanning of the silk. In the second and fourth phases intracycle behaviour consists of extension-recovery loops of the anterior segments, each followed by a repositioning of the abdomen.     

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.     

Initiation and maintenance of persistent infection by respiratory syncytial virus.

Propagation of cells infected with temperature-sensitive (ts) mutants of respiratory syncytial (RS) virus at nonpermissive temperature (39 degrees C) resulted in cytolytic, abortive, or persistent infection, depending on the mutant used to initiate infection. Five mutants from complementation group B produced cytolytic or abortive infections, whereas a single mutant (ts1) from group D and a noncomplbmenting mutant produced persistent infections. The persistently infected culture initiated by mutant ts1 (RS ts1/BS-C-1) has been maintained in serial culture for greater than 100 transfers, and infectious-center assays and immunofluorescent staining indicated that all cells harbored the RS virus genome. RS ts1/BS-C-1 cultures were resistant to superinfection by homologous and some heterologous viruses, and interferon-like activity against some heterologous viruses was present in the culture medium. Small amounts (0.002 to 0.2 PFU/cell) of infectious virus were present in the culture fluid, but autointerfering defective particles were not detected. This released virus formed small plaques and produced persistent infection of BS-C-1 cells at 37 degrees C. The RS ts1/BS-C-1 cells contained abundant RS virus antigen internally, but little at the surface, although the cells showed enhanced agglutinability by concanavalin A. Nucleocapsids and the 41,000-molecular-weight nucleoprotein were present in extracts of both nucleated and enucleated cells. No infectious RS virus was obtained by transfection of DNA from RS tsl/BS-C-1 cells to susceptible BS-C-1 or feline embryo cells under conditions allowing efficient transfection of a foamy virus proviral DNA. It was concluded that persistent infection was maintained in part by a non-ts variant of RS virus partially defective in maturation. The karyotype of the RS ts1/BS-C-1 culture differed from that of unifected cells.     

Production of an active feline interferon in the cocoon of transgenic silkworms using the fibroin H-chain expression system

We constructed the fibroin H-chain expression system to produce recombinant proteins in the cocoon of transgenic silkworms. Feline interferon (FeIFN) was used for production and to assess the quality of the product. Two types of FeIFN fusion protein, each with N- and C-terminal sequences of the fibroin H-chain, were designed to be secreted into the lumen of the posterior silk glands. The expression of the FeIFN/H-chain fusion gene was regulated by the fibroin H-chain promoter domain. The transgenic silkworms introduced these constructs with the piggyBac transposon-derived vector, which produced the normal sized cocoons containing each FeIFN/H-chain fusion protein. Although the native-protein produced by transgenic silkworms have almost no antiviral activity, the proteins after the treatment with PreScission protease to eliminate fibroin H-chain derived N- and C-terminal sequences from the products, had very high antiviral activity. This H-chain expression system, using transgenic silkworms, could be an alternative method to produce an active recombinant protein and silk-based biomaterials.     

Initiation of embryo implantation and maintenance of early pregnancy in the rat by chlordecone (Kepone).

The effect of chlordecone (Kepone), an insecticide/fungicide with reproductive toxicity, on the early stages of pregnancy in the rat was studied. Intraperitoneal injection of chlordecone into adult virgin female Holtzman strain rats before mating, in doses as high as 80 mg/kg, did not prevent fertilization, early development of the embryo to the blastocyst stage, transport of the embryo through the oviduct, or its implantation into the uterus. However, a single dose of 60 or 80 mg/kg, but not 20 or 40 mg/kg, before mating significantly reduced the concentration of progesterone in the serum of rats undergoing normal embryo implantation 5 days later. A dose of 80 mg/kg of chlordecone reduced progesterone levels in the serum by more than 50% within 48 hr in ovariectomized rats with Silastic tubing implants containing crystalline progesterone. This dose of chlordecone induced deciduomata formation in progesterone-primed ovariectomized rats to the same extent as 1 microgram of estradiol benzoate. The minimal effective single dose of chlordecone to initiate implantation of blastocysts in the uteri of hypophysectomized progesterone-primed rats, and to maintain embryo development for at least 5 days, was 50 mg/kg. Daily doses of 20 mg/kg for 3 or 5 days were effective at initiating implantation but did not maintain pregnancy. The latter treatment, however, did not prevent initiation of implantation or embryo development induced by subsequent administration of estrone. The results are consistent with the view that chlordecone is a weak estrogen that has both nongenomic and genomic estrogenic actions.     

Auditory feedback in learning and maintenance of vocal behaviour

Songbirds are one of the best-studied examples of vocal learners. Learning of both human speech and birdsong depends on hearing. Once learned, adult song in many species remains unchanging, suggesting a reduced influence of sensory experience. Recent studies have revealed, however, that adult song is not always stable, extending our understanding of the mechanisms involved in song maintenance, and their similarity to those active during song learning. Here we review some of the processes that contribute to song learning and production, with an emphasis on the role of auditory feedback. We then consider some of the possible neural substrates involved in these processes, particularly basal ganglia circuitry. Although a thorough treatment of human speech is beyond the scope of this article, we point out similarities between speech and song learning, and ways in which studies of these disparate behaviours complement each other in developing an understanding of general principles that contribute to learning and maintenance of vocal behaviour.     

Activation of saturniid moth sperm by a secretion of the male reproductive tract

Whereas sperm under storage in the seminal vesicles of male Saturniid moths are essentially motionless, they become vigorously motile when ejaculated into the spermatophore. This activation is provoked by a certain secretion of the male's ‘common duct’. The amount of activator in the secretion of a male Antheraea pernyi is prodigious: an extract of a single common duct is sufficient to induce motility in the sperm of nearly half a million male moths. Activating substances could not be recovered from any other tissues or organs of either developing or mature male moths. Nevertheless, substances capable of activating pernyi sperm were obtained from the common ducts of diverse Lepidoptera, and even from the accessory glands of two Orthoptera.Provided that the dilution was not excessive, activated silkmoth sperm in vitro remained optimally motile in a wide variety of solutions having a pH between 5·8 and 7·8 and an osmolarity between 80 and 190 milliosmols. Motility was enhanced in the presence of added protein, but was completely inhibited by dilute concentrations of heavy metal cations. Motility was normal under anaerobic conditions, and even in an atmosphere of carbon monoxide. Apparently the motility of silkmoth sperm can be sustained by glycolysis alone.     

Initiation of flight and pre-flight behaviour of anisopterous dragonflies Aeshna spp.

The start of flight of mature adult dragonflies (Aeshna spp.) was investigated using electrophysiological and photographic techniques already described. Flight begins with either an upwards or a downwards movement of the wings. Neuromuscular activity and wing vibrations resembling ‘warm-up’ in moths is reported in two species of Aeshna.     

Initiation and maintenance of in vitro decidualization are independent of hormonal sensitization in vivo.

The effects of in vivo hormonal sensitization on the competence of uterine stromal (US) cells to decidualize in vitro were assessed. In vitro differentiation of uterine stroma isolated from Day 4 pregnant rats, sensitized to respond to a decidual stimulus, was compared to that in nonsensitized immature, castrated or cycling rats. The initiation of in vitro decidualization--as monitored by the expression of the decidual markers desmin and laminin in rat US cells--was independent of the hormonal status of the animal from which the cells were isolated and occurred in the absence of serum in the medium. Differentiation was accelerated in high-density cultures where contact inhibition suppressed proliferation and decreased the extent of cell growth. The extent to which in vitro decidualization imitates in vivo stromal cell differentiation was assessed by comparing decidualization in the rabbit, a species with only a limited decidual cell response, and in the rat. US cells isolated from nonpregnant rabbits differentiated in vitro by expressing laminin, but not desmin. Indirect immunofluorescence of frozen uterine sections from pregnant and nonpregnant rabbits validated in vitro differentiation as a faithful reflection of the in vivo program of decidualization. Although the program of US cell differentiation may vary between the species, initiation of differentiation in vitro appeared to be independent of hormonal preparation in vivo for both the species examined.     

Ultrastructure of insect and spider cocoon silks

Despite much interest in the extraordinary mechanical properties of silks, the structure of native silk fibers is still not fully understood. In the present study, the morphology, topography, and organization of insect and spider cocoon silks were investigated using a range of imaging methods. Field emission scanning electron microscopy was used to observe transverse and longitude structures in silk fibers subjected to tensile fracturing, freeze fracturing, or polishing. In addition, ultrathin sections of silk brins embedded in resin were examined using transmission electron microscopy. Finally, dry silk brins were examined by confocal microscopy. The results confirmed the existence of well-oriented bundles of nanofibrils in all the silks examined and gave an indication of a hierarchical construction of the brin. Observed separation of the microfibrils in fractured brins suggests that the multifibrillar structure of the silk fiber contributes to toughness by allowing dissipation of energy in the controlled propagation of cracks.     

Agonistic behaviour,responses to a novel object and some aspects of maintenance behaviour in feral-strain and domestic chickens

Feral-strain fowl, bred from birds captured on North-West Island (24°S, 150°E), were compared with domestic chickens hatched and raised under similar conditions. Aspects of behaviour considered included agonistic behaviour and responses to unfamiliar environments and objects. There were many similarities between the feral and domestic fowl in behaviour, but there were also many differences between the strains.Feral cockerels showed higher levels of agonistic behaviour than domestic cockerels, under some conditions. There were differences between young feral and Leghorn-cross chickens in the “freezing” response to handling and placement in an unfamiliar cage, with the feral chickens responding more rapidly.Feral cockerels showed a greater initial avoidance of a novel object than did Black Australorp bantam cockerels, but after a short interval they spent more time near the novel object than the bantams.These results are discussed in relation to selection pressures under conditions of domestication, and on North-West Island.     

Initiation of apoptosis and autophagy by photodynamic therapy

This study was designed to examine modes of cell death after photodynamic therapy (PDT). Murine leukemia L1210 cells and human prostate Bax-deficient DU-145 cells were examined after PDT-induced photodamage to the endoplasmic reticulum (ER). Previous studies indicated that this treatment resulted in a substantial loss of Bcl-2 function. Both apoptosis and autophagy occurred in L1210 cells after ER photodamage with the latter predominating after 24 hr. These processes were characterized by altered cellular morphology, chromatin condensation, loss of mitochondrial membrane potential and formation of vacuoles containing cytosolic components. Western blots demonstrated processing of LC3-I to LC3-II, a marker for autophagy. In DU145 cells, PDT initiated only autophagy. Phosphatidylinositol (PI) 3-kinase inhibitors suppressed autophagy in both cell lines as indicated by inhibition of vacuolization and LC3 processing. Inhibitors of apoptosis and/or autophagy were then used to delineate the contributions of the two pathways to the effects of PDT. Given the ability of autophagy to upregulate MHC-11 peptide presentation, autophagy may play a role in the ability of photodynamic therapy to stimulate immunologic recognition of target cells.     

Initiation of Apoptosis and Autophagy by Photodynamic Therapy

This study was designed to examine modes of cell death after photodynamic therapy (PDT). Murine leukemia L1210 cells and human prostate Bax-deficient DU-145 cells were examined after PDT-induced photodamage to the endoplasmic reticulum (ER). Previous studies indicated that this resulted in a substantial loss of Bcl-2 function. Both apoptosis and autophagy occurred in L1210 after ER photodamage with the latter predominating after 24 hr. These processes were characterized by altered cellular morphology, chromatin condensation, loss of mitochondrial membrane potential, and formation vacuoles containing cytosolic components. Western blots demonstrated processing of LC3-I to LC3-II, a marker for autophagy. Inhibitors of apoptosis and/or autophagy were then used to delineate the contributions of the two pathways to the effects of PDT. In DU145 cells, PDT initiated only autophagy. PI3-kinase inhibitors suppressed autophagy in both cell lines as indicated by inhibition of vacuolization and LC3 processing. Autophagy may play a role in the ability of photodynamic therapy to stimulate immunologic recognition of target cells.

Addendum to

Initiation of Apoptosis and Autophagy by Photodynamic Therapy

D. Kessel, M.G.H. Vicente and J.J. Reiners Jr.

Lasers Surg Med 2006; In press     

Initiation of coagulation by tissue factor

Tissue factor (TF) is an integral membrane glycoprotein which functions as an initiator of coagulation. Furthermore, it is probably the principal biological initiator of this essential hemostatic process. This article reviews the studies which form the basis for these assertions. The work on TF is traced from the 19th century discovery of the thromboplastic activity of tissues to the recent purification of the protein from bovine and human tissues and the isolation cDNA clones coding from human TF. The features of TF structure and function which tailor it to the role of initiator of the coagulation cascade are considered. For example, cell-surface TF and factor VII, the plasma serine proteases zymogen, form a proteolytic complex without prior proteolysis of either component. In addition, a kinetic model for the molecular mechanism of TF-initiated clotting is reviewed. The factors which control the expression of TF procoagulant activity by cultured cells are examined in light of the hypothesized role of TF in normal hemostasis. Also, the potential pathological consequences of aberrant TF expression, i.e., thrombosis and hemorrhage, are explored.