Feeding behaviour in a population of domestic fowls in the wild

In 1976 the diet of adult feral fowls on a Scottish island consisted mainly of grass from January to July and oats from August to December. Juveniles ate many invertebrates in their first two months of life, but otherwise their diet was similar to that of the adults. In contrast to the non-breeding adults, broods and their dams showed two distinct types of feeding behaviour, called “sporadic” and “intensive” feeding. These were directed towards scattered and concentrated food sources, and the type shown depended mainly on the dam's behaviour. The significance of these and other aspects of feeding behaviour is discussed.     

鸟类性别决定候选基因在性反转鸡胚中的表达

DMRT1、PKCIW和FET1是鸟类性别决定过程中重要的候选基因。以芳香化酶抑制剂处理的鸡胚为实验材料, 对这3个基因的表达变化进行了研究。结果表明, 在整个性别决定关键时期(E4.5 ~ E10.5), DMRT1在雄性的表达量显著高于雌性, 并且在ZW性反转鸡胚中表达大幅上升, 表明DMRT1的上调表达是与睾丸形成相关的。PKCIW基因在雌性特异表达并在性反转鸡胚表达上升, 这可能与其特殊作用模式有关, 即使性反转鸡胚PKCIW代偿性的表达升高, 却也未能阻止睾丸的形成。此外, FET1为雌性特异表达, 但在性反转鸡胚中表达无变化。综上, 实验结果支持了DMRT1是鸟类睾丸发育决定因子的假说。     

Puberty onset in the female offspring of rats submitted to protein or energy restricted diet during lactation

This study aims to determine the effects of maternal protein and energy malnutrition during lactation on the linear growth, body weight and onset of puberty of the female offspring. At parturition, dams were randomly assigned to the following groups: (C) control group, with free access to a standard laboratory diet containing 23% protein; (PR) protein-restricted group, with free access to an isoenergy and protein-restricted diet containing 8% protein; and (ER) energy-restricted group, receiving standard laboratory diet in restricted quantities. After weaning, the female pups had free access to standard laboratory diet. From day 30 onwards, the pups were inspected daily for vaginal opening. Cyclic stages of the ovaries were studied by daily vaginal smears after vaginal opening until day 40 when all animals were sacrificed with pentobarbital. From day 4 after birth until day 40, body weight and linear growth in the PR and ER rats were significantly lower than in controls (p < 0.001). In spite of the significant (p<0.05) delayed in the vaginal opening in PR and ER rats, the first estrous cycle occurred at the same time of vaginal opening in all groups. The PR and ER rats exhibited a lower uterine (PR = 42%, ER = 40%, p < 0.001) and ovarian (PR = 26%, ER=19%, p < 0.05) absolute weight and uterus relative weight (PR = 27%, ER = 22%, p < 0.05). Our data showed that maternal protein and energy malnutrition during lactation leads to growth retardation and delayed on the onset of puberty in female pups, with vaginal opening and estrous cycle occurring at the same time.     

Bradykinin release and inactivation in brain of rats submitted to an experimental model of Alzheimer's disease

The kallikrein-kinin system is involved in a variety of physiological and pathological processes. Components of this system, identified in rat and human brains, can be altered in neurodegenerative processes such as Alzheimer's disease. Here, we studied kinin release and its inactivation in rats submitted to chronic cerebroventricular infusion of β-amyloid (Aβ) peptide. Neurodegeneration was confirmed by histological analysis of brain samples. In cerebrospinal fluid of animals infused with Aβ, bradykinin concentration was increased, as determined by radioimmunoassay. However, in the brain of Aβ group, we only detected the tripeptide Arg-Pro-Pro, purified by reversed-phase chromatography and characterized by liquid chromatography-electrospray ionization mass spectrometry. This fragment of bradykinin indicated the possible participation of kinin-processing enzymes in the brain such as a prolyl oligopeptidase.     

Transformation of the rete ovarii into a rete testis and the epoophoron into an epididymis after experimental sex reversal in Gallus domesticus]

Transformation of the rete ovarii into a rete testis and of the epoophoron into an epididymis after experimental sex reversal in Gallus domesticus is described. After castration of female chicks, the medulla of the left ovary and/or the right gonadal rudiment develop into a testoid or an ovotestis. From general view, this is observed as sex reversal. In case of formation of a testoid, the epoophoron develops into an epididymis and the rete ovarii develops into a rete testis which consists of intra- and extratesticular and intracapsular parts. Thus, a luminated duct system is developed which allows the transport of semen. In case of formation of an ovotestis, the discontinuously side-by-side located parts of the rete ovarii and of the epoophoron are maintained.     

Differential expression of P450 aromatase during gonadal sex differentiation and sex reversal of the newt Pleurodeles waltl

A better understanding of vertebrate sexual differentiation could be provided by a study of models in which genetic sex determination (GSD) of gonads can be reversed by temperature. In the newt Pleurodeles waltl, a P450 aromatase cDNA was isolated from adult gonads, and the nucleotide or deduced amino acid sequences showed a high level of identity with various vertebrate species. In adults, aromatase expression was found in gonads and brain. In developing gonads, the expression was found to fit with the thermo-sensitive period (TSP) and was detected in both ZZ and ZW larvae, as well as in ZW submitted during the whole TSP to a masculinizing temperature. In the latter individuals, in situ hybridization and semi quantitative RT-PCR showed that, at the end of TSP, aromatase expression was at the same level than in normal ZZ larvae and was significantly lower than in normal ZW ones. Furthermore, temperature-induced down regulation did not occur when heating was performed at the end of TSP. Our results confirm the importance of aromatase regulation in female versus male differentiation and demonstrate that a down regulation of aromatase expression is involved in the process of sex reversal.     

A cost of Wolbachia-induced sex reversal and female-biased sex ratios: decrease in female fertility after sperm depletion in a terrestrial isopod

A number of parasites are vertically transmitted to new host generations via female eggs. In such cases, host reproduction is an intimate component of parasite fitness and no cost of the infection on host reproduction is expected to evolve. A number of these parasites distort host sex ratios towards females, thereby increasing either parasite fitness or the proportion of the host that transmit the parasite. In terrestrial isopods (woodlice), Wolbachia bacteria are responsible for sex reversion and female-biased sex ratios, changing genetic males into functional neo-females. Although sex ratio distortion is a powerful means for parasites to increase in frequency in host populations, it also has potential consequences on host biology, which may, in turn, have consequences for parasite prevalence. We used the woodlouse Armadillidium vulgare to test whether the interaction between Wolbachia infection and the resulting excess of females would limit female fertility through the reduction in sperm number that they receive from males. We showed that multiple male mating induces sperm depletion, and that this sperm depletion affects fertility only in infected females. This decrease in fertility, associated with male mate choice, may limit the spread of Wolbachia infections in host populations.     

Masculinization of female golden rabbitfish Siganus guttatus using an aromatase inhibitor treatment during sex differentiation

To elucidate the involvement of endogenous estrogen (estradiol-17beta; E2) and the decisive factor (somatic or germinal element) in the ovarian differentiation of tropical marine teleosts, the effect of the aromatase inhibitor (AI) fadrozole on gonadal sex differentiation in the golden rabbitfish Siganus guttatus (Bloch) was examined for different dosages and periods of treatment. Fadrozole interrupted ovarian cavity formation at a dose of 500 microg g(-1) diet, while there was little effect at 10 or 100 microg g(-1). The gonads from both the 30-day and 90-day administration (500 microg g(-1) diet) groups were significantly biased toward testes (P=0.002 and <0.0001, respectively), which suggests strongly that E2 is involved in early ovarian differentiation and that its suppression is an indispensable condition for testicular differentiation in S. guttatus. The results from the two different AI treatment periods imply that the initial feminization of somatic gonadal elements determines subsequent ovarian differentiation, including oogenesis: a conclusion supported by the considerable time lag between ovarian cavity formation and subsequent oogenesis during normal ovarian differentiation in S. guttatus.     

Circadian features of carbohydrate metabolism in domestic fowls exposed to weekly 120 degree-shifts of synchronizer schedule.

Effects of weekly 8 hr advance- or delay-shifts on the circadian rhythm of plasma glucose, liver glycogen and muscle glycogen in male domestic fowls, beginning at about 3 days of age, were examined. Circadian rhythm in the aforesaid indices of carbohydrate metabolism in control birds was also studied. Blood and tissue samples were collected from birds in all the three groups at 4 hr intervals over a single 24 hr time scale both at 6th and 12th week of age. Plasma glucose and glycogen content in the tissues were determined by employing standard techniques. Cosinor rhythmometry was used for analyzing time series data. In general, a statistically significant circadian rhythm was documented for all the three indices in control and advance-schedule birds, irrespective of age. In contrast, in delay-schedule birds, statistically significant circadian rhythm could not be detected, excluding in muscle glycogen at 12th week of age. The poor growth rate in the delay-schedule birds could be imputed to the disappearance of circadian rhythm in the indices of carbohydrate metabolism.