Charting the course of ovarian development in vertebrates

The decision of the embryonic gonad to differentiate as either a testis or an ovary is a critical step in vertebrate development. The molecular basis of this decision has been the focus of much study, particularly over the past decade. Here we contrast the knowledge of early gonadal development and the switch to testis differentiation with the lack of molecular understanding of ovarian development at early stages. We review current knowledge regarding mechanisms of ovarian morphogenesis and propose a model for the hierarchical control of development of the fetal ovary, incorporating the few genes already known to be important and several signals or factors that are hypothesised to exist in the early ovary.

On the intrinsic capacity for increase of Australian flying-foxes (Pteropus spp., Megachiroptera)

In the reproductive biology of organisms, a continuum exists from "highly reproductive species" at one end to "survivor species" at the other end. Among other factors, the position of a species along this continuum affects its sensitivity to human exploitation and its vulnerability to extinction. Flying foxes are long-lived, seasonal breeders, with a rigid, well-defined breeding season that is largely or wholly genetically determined. Unlike opportunistic, highly reproductive species, such as rabbits or mice, female flying foxes are unable to produce viable young before their second or third year of life, and are then capable of producing just one young per year. Such a breeding strategy will be successful only if flying-foxes are long-lived and suffer naturally low mortality rates. In this paper, we assess the vulnerability of flying foxes to extinction, using basic parameters of reproduction observed in the wild, and in captive breeding colonies of P. poliocephalus, P. alecto and P. scapulatus, and survival rates that are likely to apply to Australian conditions. Our models show explicitly that flying-fox populations have a very low capacity for increase, even under the most ideal conditions. The implications of our models are discussed in reference to the long-term management and conservation needs of Australian flying foxes. We conclude that current death-rates of flying-foxes in NSW and Queensland fruit orchards are putting state populations at serious risk.

Role of PGF(2 alpha) and oxytocin in parturition in the brushtail possum (Trichosurus vulpecula)

Maturation of the fetal pituitary and adrenal glands allows the secretion of cortisol, which in turn leads to an increase in prostaglandin and mesotocin production. The production of prostaglandin and mesotocin results in an increase in uterine contractions and initiates birth in marsupials. The major metabolite of PGF(2alpha), 13,14-dihydro-15-keto-prostaglandin F-2alpha (PGFM), has been found in the plasma of the possum at the time of birth and administration of PGF(2alpha) to female possums induced the adoption of the birth position. Evidence that mesotocin is an integral hormone of birth in the tammar wallaby indicates that both PGF(2alpha) and mesotocin or oxytocin are required for marsupial birth. The presence of PGF(2alpha) receptors in the uterus and corpus luteum of the possum, and the in vitro uterine responsiveness to PGF(2alpha) or oxytocin, were examined. PGF(2alpha) receptors were not observed in possum uteri and the inability of PGF(2alpha) to cause contractions indicates that PGF(2alpha) is not involved directly in contraction of the uterus at parturition. The presence of oxytocin and mesotocin receptors in the uterus of possoms and the ability of oxytocin to induce uterine contraction in vitro supports the view that mesotocin is required for expulsion of the young from the uterus. Low numbers of PGF(2alpha) receptors were found in the possum corpus luteum at birth, indicating an involvement of PGF(2alpha) in regression of the corpus luteum.

Behavioural responses of two native Australian fish species (Melanotaenia duboulayi and Pseudomugil signifer) to introduced poeciliids (Gambusia holbrooki and Xiphophorus helleri) in controlled conditions

Experimental treatments to compare behavioural responses included native fish species only, natives plus one exotic species and natives plus both exotic species. The mosquitofish, Gambusia holbrooki frequently attacked both native species, but tended to nip Melanotaenia duboulayi (especially small individuals) and chase Pseudomugil signifer The frequency of attacks by G. holbrooki on M. duboulayi rose when all four fish species were present. When food was added, all four species showed a strong increase in aggression, especially in the four-species treatment, where there were significant increases in the frequency of attacks by the swordtail Xiphophorus helleri on M. duboulay and by M. duboulayi on G. holbrooki, and of conspecific attacks by M. duboulayi. Increased attack frequency was associated with aggregation closer to the water's surface, regardless of the presence of food. The results support the hypothesis that introduced poeciliids can have deleterious competitive effects on native species. However, while juvenile M. duboulayi were particularly vulnerable to the secondary, effects of fin-nipping, R signifer appeared to be more susceptible to physical displacement and reduced food capture success.

Energetic costs of tail loss in a montane scincid lizard

Most species of lizards will shed their tails at the point of contact when grasped by a predator. We investigated the energetic consequences of tail loss by measuring lipids in a scincid lizard that stores energy in its tail for reproduction. Most of the lipids were concentrated in the proximal portion of the tail. Thus, partial tail loss may not severely affect energy stores if the distal portion of the tail is shed in predatory encounters. We also found that the width of the tail was a reliable non-invasive index of energy reserves in this species. (C) 2003 Elsevier Science Inc. All rights reserved.

Genetic structure of a population of Ganoderma boninense on oil palm

Ganoderma boninense (the causal agent of basal stem rot of oil palm in Papua New Guinea) has a tetrapolar mating system with multiple alleles. Investigations into the population structure of G. boninense, using interfertility between isolates as a marker, revealed that the population on oil palm was comprised predominantly of genetically distinct individuals, although a number of isolates were found to share single mating alleles. No direct hereditary relationship was found between isolates on neighbouring or spatially separated diseased palms, indicating that outcrossing had probably occurred over several generations in the founder population prior to colonization of oil palm. In this study, a total of 81 A and 83 B mating type alleles (factors) were detected with 18 allelic repeats at the A locus and 17 at the B locus. Alleles appeared to be randomly dispersed throughout the population in each study block, although there was a significantly (P

Birth of Koalas Phascolarctos cinereus at Lone Pine Koala Sanctuary following artificial insemination

This paper documents the successful development of an artificial insemination (AI) programme for the Koala Phascolurctos cinereus. The protocols for trials involving two methods to induce ovulation and two insemination techniques are described. In Trial 1, interrupted coitus using a 'teaser'♂ successfully induced ovulation in nine Koalas. Five ♀♀ were inseminated while conscious using a modified 'foley catheter' (Cook insemination catheter) resulting in the births of two offspring. The other four ♀♀ were anaesthetized and inseminated using a technique which allowed visualization of the most cranial portion of the urogenital sinus, where semen was deposited using a 3.5 Fr. 'Tom-cat catheter' (urogen-itoscopic insemination). Three of the four ♀♀ inseminated by this technique produced pouch young. Microsatellite analysis of DNA from the pouch young excluded the teaser ♀♀ as possible sires, confirming that all offspring were sired by donor sperm. In Trial 2, eight ♀♀ were induced to ovulate by injecting them with 250 International Units of human chorionic gonadotrophin (hCG). A luteal phase was confirmed in all eight ♀♀ but only one gave birth following urogenitoscopic insemination. The Koala pouch young in this study are the first of any marsupial to be conceived and born following A1 procedures. Details of the A1 procedures used are presented and the significance of A1 to the conservation biology of P. cinereus discussed.

A molecular phylogeny of the Australian skink genera Eulamprus, Gnypetoscincus and Nangura

Skinks from the genera Eulamprus, Gnypetoscincus and Nangura are a prominent component of the reptile fauna of the mesic forests of the east coast of Australia and have been the subject of numerous ecological studies. Highly conserved morphology and the retention of ancestral traits have limited our understanding of the relationships within and among these genera beyond an initial identification of species groups within Eulamprus. To address this deficit and to explore the relationships between Eulamprus and the monotypic genera Nangura and Gnypetoscincus, sections of two mitochondrial genes (ND4 and 16S rRNA) were sequenced and subjected to Bayesian phylogenetic analysis. This phylogenetic analysis supports recognition of the three species groups proposed for Eulamprus (murrayi, quoyii and tenuis) and indicates that this genus is paraphyletic, with Gnypetoscincus and Nangura being proximal to basal lineages of the tenuis group. To resolve these and broader problems of paraphyly, we suggest that each of the species groups from 'Eulamprus' should be recognised as a distinct genus. The phylogenetically and ecologically distinct water skinks of the quoyii group would be retained within Eulamprus and the diverse species of the tenuis group allocated to Concinnia. We suggest placing the monophyletic murrayi group, endemic to the rainforests of central eastern Australia, in a new genus ( yet to be formally described). The sequencing data also revealed the existence of a genetically divergent but morphologically cryptic lineage within E. murrayi and substantial diversity within E. quoyii. There is evidence for two major habitat shifts from rainforest towards drier habitats, one leading to the quoyii group and the second defining a clade of three species within the tenuis complex. These ecological transitions may represent adaptations to general drying across eastern Australia during the late Miocene - Pliocene. Each of the major areas of east coast tropical or subtropical rainforest contains multiple phylogenetically diverse endemic species, reflecting the long-term persistence and high conservation value of wet forest habitats in each area.

Genetic structure of Mycosphaerella fijiensis populations from Australia, Papua New Guinea and the Pacific Islands

Single-copy restriction fragment length polymorphism (RFLP) markers were used to determine the genetic structure of Mycosphaerella fijiensis, the cause of black leaf streak (black Sigatoka) disease of banana and plantain, in the Torres Strait, Papua New Guinea (PNG), and the Pacific Islands. A moderate level of genetic variation was observed in all populations with genotypic diversity values of 60-78% of the theoretical maximum, and gene diversity (H) values between 0.269 and 0.336. All populations were at gametic equilibrium, and with the high level of genotypic diversity observed this indicated that sexual reproduction has a major role in the genetic structure of the M. fijiensis populations examined. Population differentiation was tested on several hierarchical scales. No evidence of population differentiation was observed between sites on Mer Island. A moderate level of population differentiation was observed within the Torres Strait, between Badu and Mer Islands (F-ST = 0.097). On a regional scale, the greatest differentiation was found between the populations of the Torres Strait and the Pacific. Populations from these regions were more closely related to the PNG population than to each other, suggesting they were founded in separate events from the same population.

Novas tend??ncias do mercado de trabalho

Na ruptura social fordista, o desemprego cresce bruscamente, fazendo surgir configura????es vari??veis, onde o conceito de press??o salarial passa a designar o complemento monet??rio indireto, destinado a assegurar a reprodu????o intergeneracional nas sociedades capitalistas plenamente desenvolvidas. A nova rela????o salarial compreende a rela????o de emprego (rela????o monet??ria direta) e a press??o salarial (rela????o monet??ria indireta). O aparecimento de rela????es de trabalho prec??rias for??a a press??o salarial a substituir a prote????o social em decad??ncia. Dos arranjos em forma????o, impor-se-??o os que encontrarem uma coer??ncia sist??mica m??nima. O poder p??blico agir?? como regulador da rela????o salarial e garantidor ??ltimo da press??o salarial, respeitando a flexibilidade do aparelho produtivo e a mobilidade e flexibilidade do trabalho. O autor tra??a trajet??rias nacionais baseados em 2 cen??rios estilizados, que s??o a variante americana (modelo t??pico da desregulamenta????o e flexibilidade externa) e a variante europ??ia (modelo t??pico da gest??o institucionalizada e flexibilidade interna).

As políticas de proteção social no contexto escolar

Esta dissertação teve o objetivo de investigar como a formalização das políticas de proteção social via programas e projetos socioeducativos se articulam com a educação escolarizada. Realiza uma discussão conceitual acerca das políticas de proteção social e “vulnerabilidade e risco social” a partir de aspectos históricos situando-as na lógica societária das desigualdades e complexificações das refrações da questão social do modelo capitalista de produção e reprodução social, sobretudo no contexto das reformas do Estado brasileiro enquanto demanda dos ajustes neoliberais. O lócus da pesquisa foi uma escola da rede pública municipal de Serra/ES. As investigações foram realizadas em duas etapas. A primeira constituiu-se de um estudo exploratório de caráter qualitativo. Por meio das análises abstraídas dessa fase, foi realizado um estudo de caso como segunda etapa da pesquisa. Os instrumentos utilizados, análise de documentos, observação participante e entrevistas, evidenciam que os programas e projetos socioeducativos desenvolvidos no espaço escolar visando a uma suposta proteção social, não guardam relação concreta com a melhoria dos processos de aprendizagem dos alunos, logo, seus efeitos na vida escolar desses alunos não foram evidenciados. Verificou-se ainda profunda desarticulação entre as propostas pedagógicas da escola e dos docentes com os programas e projetos investigados. A partir dos dados da pesquisa, pudemos ainda constatar que tais programas e projetos adentram o espaço escolar por meio de demandas externas envolvendo a Secretaria Municipal de Educação e a iniciativa privada. Concluímos que a proteção social no espaço escolar via programas e projetos socioeducativos necessita voltar-se à articulação com políticas públicas que ultrapassem os muros da escola e que de fato garantam o acesso a bens materiais e simbólicos com vista à melhoria das condições de vida material e sociocultural dos alunos a quem são destinados e, consequentemente, a melhoria da qualidade da educação escolarizada.

A narratividade do Hip Hop e suas interfaces com o contexto educacional

A presente tese de doutoramento em Educação aborda a cultura do Hip Hop e sua relação com o contexto educativo. Insere-se nas discussões da linha de pesquisa em Educação e Linguagens e problematiza o espaço escolar, enquanto espaço de reprodução da ideologia hegemônica, analisando o projeto “Escola de Rimas”, desenvolvido na Grande Vitória, como movimento de resistência e ressignificação cultural na escola. Parte da pergunta: Como as práticas discursivas do Hip Hop podem ressignificar o contexto escolar? A presente tese aborda a cultura do Hip Hop como campo discursivo singular de uma experiência narrativa (BENJAMIN, 1986; BONDÍA, 2001) e de uma subjetividade eticamente responsável (BAKHTIN, 1992a; 1992b; 2010), fundada no princípio da alteridade (PONZIO, 2009), e o analisa a partir de uma perspectiva crítica e dialógica (FREIRE, 1981; 1994; 1995; GIROUX, 1986; 1987; BRANDÃO, 1986; BAKHTIN, 1992a; 1992b; 2010). Desenvolve a pesquisa em um contexto limiar entre a escola e a cultura hip hop e dimensiona o debate das culturas marginais nos contextos educativos, voltando-se para os sujeitos e suas experiências narrativas, avaliando a interação de algumas de suas práticas discursivas com o processo de ensino-aprendizagem. Para isso, analisa o projeto cultural “Escola de Rimas”, criado pelos próprios ativistas do movimento hip hop da Grande Vitória e desenvolvido em uma escola da rede pública estadual de ensino do Espírito Santo, com o objetivo de discutir o seu papel em um processo de ressignificação educacional. Como hipótese de trabalho defende-se que o espaço escolar, como espaço de disputas, é ressignificado com a introdução de outras práticas discursivas e culturais, entre elas o hip hop, que aponta para a necessidade de ouvir responsiva e responsavelmente as narrativas dos educandos, contribuindo, assim, para a formação crítica desses sujeitos e enfrentando, ao mesmo tempo, práticas de exclusão historicamente instituídas.