Analysis of zinc transporter, hZnT4(Slc30A4), gene expression in a mammary gland disorder leading to reduced zinc secretion into milk

Zinc deficiency, causing impaired growth and development, may have a nutritional or genetic basis. We investigated two cases of inherited zinc deficiency found in breast-fed neonates, caused by low levels of zinc in the maternal milk. This condition is different from acrodermatitis enteropathica but has similarities to the "lethal milk" mouse, where low levels of zinc in the milk of lactating dams leads to zinc deficiency in pups. The mouse disorder has been attributed to a defect in the ZnT4 gene. Little is known about the expression of the human orthologue, hZnT4 (Slc30A4). Sequence analysis of cDNA, real-time PCR and Western blot analysis of hZnT4, carried out on control cells and cells from unrelated mothers of two infants with zinc deficiency, showed no differences. The hZnT4 gene was highly expressed in mouthwash buccal cells compared with lymphoblasts and fibroblasts. The hZnT4 protein did not co-localise with intracellular free zinc pools, suggesting that hZnT4 is not involved in transport of zinc into vesicles destined for secretion into milk. This observation, combined with phenotypic differences between the "lethal milk" mouse and the human disorder, suggests that the "lethal milk" mouse is not the corresponding model for the human zinc deficiency condition.

Osmoregulation in elephant fish Callorhinchus Milii (Holocephali), with special reference to the rectal gland

Osmoregulatory mechanisms in holocephalan fishes are poorly understood except that these fish are known to conduct urea-based osmoregulation as in elasmobranchs. We, therefore, examined changes in plasma parameters of elephant fish Callorhinchus milii, after gradual transfer to concentrated (120%) or diluted (80%) seawater (SW). In control fish, plasma Na and urea concentrations were about 300 mmol l^–1 and 450 mmol l^–1, respectively. These values were equivalent to those of sharks and rays, but the plasma urea concentration of elephant fish was considerably higher than that reported for chimaeras, another holocephalan. After transfer to 120% SW, plasma osmolality, urea and ion concentrations were increased, whereas transfer to 80% SW resulted in a fall in these parameters. The rises in ion concentrations were notable after transfer to 120% SW, whereas urea concentration decreased predominantly following transfer to 80% SW. In elephant fish, we could not find a discrete rectal gland. Instead, approximately 10 tubular structures were located in the wall of post-valvular intestine. Each tubular structure was composed of a putative salt-secreting component consisting of a single-layered columnar epithelium, which was stained with an anti-Na⁺,K⁺-ATPase serum. Furthermore, Na⁺,K⁺-ATPase activity in the tubular structures was significantly increased after acute transfer of fish to concentrated SW (115%). These results suggest that the tubular structures are a rectal gland equivalent, functioning as a salt-secreting organ. Since the rectal gland of elephant fish is well developed compared to that of Southern chimaera, the salt-secreting ability may be higher in elephant fish than chimaeras, which may account for the lower plasma NaCl concentration in elephant fish compared to other chimaeras. Since elephant fish have also attracted attention from a viewpoint of genome science, the availability of fish for physiological studies will make this species an excellent model in holocephalan fish group.

Fur seal adaptations to lactation: insights into mammary gland function

The fur seal (Arctocephalus spp. and Callorhinus spp., members of the pinniped family) is a mammal with the unusual capability to modulate its lactation cycle by turning milk production on and off without the typical mammalian regression and involution of the mammary gland. Lactation has evolved from constraints arising from the spatial and temporal separation of infant nursing and maternal foraging as the mother gives birth and feeds the pup on land while acquisition of nutrients for milk production occurs at sea. The lactation cycle begins with the female fur seal undergoing a perinatal fast of approximately 1 wk, after which time she departs the breeding colony to forage at sea. For the remainder of the long lactation period (116–540 days), the mother alternates between short periods ashore suckling the young with longer periods of up to 4 wk of foraging at sea. Milk production continues while foraging at sea, but at less than 20% the rate of production on land. Fur seals produce one of the richest milk reported, with a very high lipid content contributing up to 85% of total energy. This feature serves as an adaptation to the young's need to produce an insulating blubber layer against heat loss and to serve as an energy store when the mother is away foraging at sea. This atypical pattern of lactation means mothers have long periods with no suckling stimulus and can transfer high-energy milk rapidly while on land to minimize time away from foraging grounds. The absence of suckling stimulus and milk removal during foraging does not result in the onset of involution with associated apoptosis of mammary secretory cells and a subsequent progressive breakdown of the cellular structure of the mammary gland. The mechanisms controlling lactation in the fur seal mammary gland have been investigated using molecular and cellular techniques. These findings have shed light on the processes by which the unique features of lactation in the fur seal are regulated.

Eri silk fibre attributes and sliver preparation

Eri silk produced by Philosamia cynthia ricini silkworm is a fibre not well-known to the silk industry, in spite of the fact that Eri silk is finer, softer, and has better mechanical and thermal properties than most animal fibres. Eri silk has a high commercial potential, as the host plants of Eri silk worms are widespread in diverse geographical locations, and the worms also have a higher degree of disease resistance than most other silk worms. Mills are often not aware of the properties of Eri for designing appropriate end products. Thus, Eri silk yarn is traditionally produced by hand spinning, and Eri silk usually ends up as material for handwoven shawls. The potential for bulk fibre processing and the development of soft luxurious novel Eri silk products is yet to be discovered. To better understand the material and its processing behaviour, Eri silk was characterised and cocoons were processed into tops through degumming, opening, and cutting filaments into different lengths, followed by a worsted spun silk processing route. Fibre properties such as fineness, crimp, strength and length at different processing stages up to combed tops were measured. The results indicate that staple Eri silk can be processed via the worsted topmaking route, using a cut length of 200 mm or 150 mm for filament sheets prepared from degummed cocoons.

Silk Road project

Choreographer Kim Vincs and Scenographer Matthew Delbridge worked with dancer, Carlee Mellow, musicians Rob Vincs, Scott Dunbabin and Eugene Ughetti to create a virtual visual performance where performer's movement was rendered using a motion capture system and projected onto translucent screens.

Maternity waiting homes in Southern Lao PDR : the unique 'silk home'

The concept of maternity waiting homes (MWH) has a long history spanning over 100 years. The research reported here was conducted in the Thateng District of Sekong Province in southern Lao People’s Democratic Republic (PDR) to establish whether the MWH concept would be affordable, accessible, and most importantly acceptable, as a strategy to improve maternal outcomes in the remote communities of Thateng with a high proportion of the population from ethnic minority groups. The research suggested that there were major barriers to minority ethnic groups using existing maternal health services (reflected in very low usage of trained birth attendants and hospitals and clinics) in Thateng. Unless MWH are adapted to overcome these potential barriers, such initiatives will suffer the same fate as existing maternal facilities. Consequently, the Lao iteration of the concept, as operationalized in the Silk Homes project in southern Lao PDR is unique in combining maternal and infant health services with opportunities for micro credit and income generating activities and allowing non-harmful traditional practices to co-exist alongside modern medical protocols. These innovative approaches to the MWH concept address the major economic, social and cultural barriers to usage of safe birthing options in remote communities of southern Lao PDR.

Lack of functional alpha-lactalbumin prevents involution in Cape fur seals and identifies the protein as an apoptotic milk factor in mammary gland involution

The mammary gland undergoes a sophisticated programme of developmental changes during pregnancy/lactation. However, little is known about processes involving initiation of apoptosis at involution following weaning. We used fur seals as models to study the molecular process of involution as these animals display a unique mammary gland phenotype. Fur seals have long lactation periods whereby mothers cycle between secreting copious quantities of milk for 2 to 3 days suckling pups on land, with trips to sea alone to forage for up to 23 days during which time mammary glands remain active without initiating apoptosis/involution.

Fabrication of ultrafine powder from eri silk through attritor and jet milling

Fibroin protein derived from silk fibres has been extensively studied with exciting outcomes for a number of potential advanced biomaterial applications. However, one of the major challenges in applications lies in engineering fibroin into a  desired form using a convenient production technology. In this paper, fabrication of ultrafine powder from eri silk is reported. The silk cocoons were degummed and the extracted silk fibres were then chopped into snippets prior to attritor and air jet milling. Effects of process control agents, material load and material to water ratio during attritor milling were studied. Compared to dry and dry–wet attritor milling, wet process emerged as the preferred option as it caused less colour change and facilitated easy handling. Ultrafine silk powder with a volume based particle size d(0.5) of around 700 nm could be prepared following the sequence of chopping ➔ wet attritor milling ➔ spray drying ➔ air jet milling. Unlike most reported powder production methods, this method could fabricate silk particles in a short time without any pre-treatment on degummed fibre. Moreover, the size range obtained is much smaller than that previously produced using standard milling devices. Reduction in fibre tenacity either shortened the milling time even further or helped bypassing media milling to produce fine powder directly through jet milling. However, such reduction in fibre strength did not help in increasing the ultimate particle fineness. The study also revealed that particle density and particle morphology could be manipulated through appropriate changes in the degumming process.

Graphical Abstract:  Fabrication of eri silk powder using attritor and jet milling is reported. Volume based particle size d(0.5) of around 700 nm could be prepared following the sequence chopping ➔ wet attritor milling ➔ spray drying ➔ air jet milling. No pre-treatments were used and the particle size range obtained is much smaller than that previously produced using standard milling devices. Particle density morphology could be manipulated through appropriate changes of cocoon degumming conditions.

Grafts in myringoplasty : utilizing a silk fibroin scaffold as a novel device

Chronic perforations of the eardrum or tympanic membrane represent a significant source of morbidity worldwide. Myringoplasty is the operative repair of a perforated tympanic membrane and is a procedure commonly performed by otolaryngologists. Its purpose is to close the tympanic membrane, improve hearing and limit patient susceptibility to middle ear infections. The success rates of the different surgical techniques used to perform a myringoplasty, and the optimal graft materials to achieve complete closure and restore hearing, vary significantly in the literature. A number of autologous tissues, homografts and synthetic materials are described as graft options. With the advent and development of tissue engineering in the last decade, a number of biomaterials have been studied and attempts have been made to mimic biological functions with these materials. Fibroin, a core structural protein in silk from silkworms, has been widely studied with biomedical applications in mind. Several cell types, including keratinocytes, have grown on silk biomaterials, and scaffolds manufactured from silk have successfully been used in wound healing and for tissue engineering purposes. This review focuses on the current available grafts for myringoplasty and their limitations, and examines the biomechanical properties of silk, assessing the potential benefits of a silk fibroin scaffold as a novel device for use as a graft in myringoplasty surgery.

Fabricating and characterising silk powder for biomedical and sorption applications

This research developed a milling technology for ultrafine silk particles and designed novel biocompatible and biodegradable silk composites for repairing hard tissue defects. It also demonstrated high and rapid reversible ion binding properties of silk particles and thereby opened up their application opportunities as advanced green sorbents.

Preliminary results of the application of a silk fibroin scaffold to otology

The surgical treatment to repair chronic tympanic membrane perforations is myringoplasty. Although multiple autologous grafts, allografts, and synthetic graft materials have been used over the years, no single graft material is superior for repairing all perforation types. Recently, the remarkable properties of silk fibroin protein have been studied, with biomedical and tissue engineering applications in mind, across a number of medical and surgical disciplines. The present study examines the use of silk fibroin for its potential suitability as an alternative graft in myringoplasty surgery by investigating the growth and proliferation of human tympanic membrane keratinocytes on a silk fibroin scaffold in vitro. Light microscopy, immunofluorescent staining, and confocal imaging all reveal promising preliminary results. The biocompatibility, transparency, stability, high tensile strength, and biodegradability of fibroin make this biomaterial an attractive option to study for this utility.