The negative correlation between fattening and laying performance prevents breeding improvement in both laying performance and meat yield. Therefore, specialized chicken lines have been bred in order to achieve either an efficient production of high-quality eggs or high growth rates. As a result, day-old male chicks are culled in the layer hatchery, which poses animal welfare and ethical problems. Breeding companies, scientific groups, and hatcheries are attempting to resolve this issue, with a common aim to find feasible alternatives for the routine killing of male layer chicks. Some approaches aim to influence the sex ratio, while others target at the economically feasible use of the male layer offspring, such as the fattening of "laying hen brothers" or crossbreedings of layers and broilers to create "dual-purpose chickens." Another approach is the sex determination prior to hatch. One of the prerequisites of in ovo sex determination is a practicable method that can be used in industry. The analysis needs to be rapid, cost-efficient, and highly precise; in addition, negative impacts on hatching rate, animal health, and/or performance parameters should be limited. Furthermore, sex determination should be performed before the sensory nervous system's response of the chick embryo to certain or potentially harmful stimuli is developed, which according to current knowledge is before the d 7 of incubation.

Domesticated birds exhibit a greater diversity in the morphology of their integument and its appendages than their wild ancestors. Many of these variations affect the appearance of a bird significantly and have been bred selectively by poultry and pigeon fanciers and aviculturists for the sake of visual appeal. Variations in feather distribution (e.g., feathering of legs and feet, featherless areas in normally feather-bearing skin) are widespread in chickens and pigeons. Variations in the number of feathers (e.g., increased number of tail feathers, lack of tail feathers) occur in certain pigeon and poultry breeds. Variations in feather length can affect certain body regions or the entire plumage. Variations in feather structure (e.g., silkiness, frilled feathering) can be found in exhibition poultry as well as in pet birds. Variations in feather arrangement (e.g., feather crests and vortices) occur in many domesticated bird species as a results of mutation and intense selective breeding. The causes of variations in the structure, distribution, length and arrangement of feathers is often unknown and opens a wide field for scientific research under various points of view (e.g., morphogenesis, pathogenesis, ethology, etc.). To that extent, variations in the morphology, distribution and arrangement of feathers in domesticated birds require also a concern for animal welfare because certain alleles responsible for integumentary variations in domesticated birds have pleiotropic effects, which often affect normal behaviour and viability.

In order to provide an alternative to day-old chick culling in the layer hatcheries, a noninvasive method for egg sexing is required at an early stage of incubation before onset of embryo sensitivity. Fluorescence and Raman spectroscopy of blood offers the potential for precise and contactless in ovo sex determination of the domestic chicken (Gallus gallus f. dom.) eggs already during the fourth incubation day. However, such kind of optical spectroscopy requires a window in the egg shell, is thus invasive to the embryo and leads to decreased hatching rates. Here, we show that near infrared Raman and fluorescence spectroscopy can be performed on perfused extraembryonic vessels while leaving the inner egg shell membrane intact. Sparing the shell membrane makes the measurement minimally invasive, so that the sexing procedure does not affect hatching rates. We analyze the effect of the membrane above the vessels on fluorescence signal intensity and on Raman spectrum of blood, and propose a correction method to compensate for it. After compensation, we attain a correct sexing rate above 90% by applying supervised classification of spectra. Therefore, this approach offers the best premises towards practical deployment in the hatcheries.

Transgenic mouse models were established to study tumorigenesis of bronchiolo-alveolar adenocarcinomas derived from alveolar type II pneumocytes (AT-II cells). Transgenic lines expressing the murine oncogene c- myc under the control of the lung-specific surfactant protein C promoter developed multifocal bronchiolo-alveolar hyperplasias, adenomas and carcinomas respectively, whereas transgenic lines expressing a secretable form of the epidermal growth factor (IgEGF), a structural and functional homologue of transforming growth factor α (TGFα), developed hyperplasias of the alveolar epithelium. Since the oncogenes c- myc and TGFα are frequently overexpressed in human lung bronchiolo-alveolar adenocarcinomas, these mouse lines are useful as models for human lung bronchiolo-alveolar adenocarcinomas. The average life expectancies of hemizygous and homozygous c- myc transgenics were 14.25 months and 9.2 months, respectively, suggesting that a dosage effect of c- myc caused an accelerated bronchiolo-alveolar adenocarcinoma formation. First analyses of double transgenics, hemizygous for both c- myc and IgEGF, show that these mice develop bronchiolo-alveolar adenocarcinomas at the average age of 9 months, indicating that these oncogenes cooperate during the lung cancer formation. Our results demonstrate that c- myc and EGF are directly involved and cooperate with one another during formation of bronchiolo-alveolar adenocarcinomas in the lung. © 2001 Cancer Research Campaign http://www.bjcancer.com

The potentially enhanced mitogenic activity of insulin analogs represents a safety risk that requires detailed analysis of new analogs considered for therapeutic applications. We assessed the signaling properties and mitogenic potency of two novel rapid-acting insulin analogs, Lys Insulin therapy of diabetic patients aims to achieve tight blood glucose control to reduce the progression of long-term complications (1). However, the pharmacokinetic characteristics of currently available insulin preparations are unable to mimic the pattern of endogenous insulin secretion and make it impossible to achieve sustained normoglycemia (2). Great efforts have been made to develop novel insulin molecules with altered pharmacodynamic characteristics that might lead to improved glycemic control using recombinant DNA technology (rev. in 3-5). One limiting factor is the slow absorption of conventional unmodified insulin from subcutaneous tissues because of the slow dissociation rate of hexameric insulin complexes into monomers at the injection site (6,7). Modification of the B26ϪB30 region of the insulin molecule, particularly substitution of amino acids with charged residues at the association sites, allows the production of a range of insulin analogs with reduced selfassociation that exhibit no profound perturbations of insulin receptor recognition (4,8). This has been demonstrated for insulin analogs such as Lispro (Lys B28 ,Pro B29 ) insulin and insulin aspart (Asp B28 insulin), two rapidacting insulins that are in clinical use and improve postprandial glycemic control (3,5).A major concern related to the long-term use of insulin analogs stems from the observation that modification of the insulin molecule in the B10 and B26ϪB30 regions alters the affinity for the IGF-I receptor more than for the insulin receptor and may lead to enhanced mitogenic activity of these analogs (9). This potential safety risk was first recognized for the analog Asp B10 insulin, which was found to exhibit a tumor-promoting activity in SD rats (10) and to induce a profound mitogenic effect in many cell systems (11-13). The enhanced mitogenic signaling profile of an insulin analog may result from 1) an increased affinity toward the IGF-I receptor, resulting in augmented IGF-I receptor signaling (9); 2) the so-called time-dependent specificity that describes a distinct correlation between the mitogenic potential and the occupancy time at the insulin receptor for a given insulin analog (14); and 3) a combination of both IGF-I and insulin receptorϪ mediated processes. Most recent data suggest that the mitogenic properties correlate better with the IGF-I recep-