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Search Results: 1 - 10 of 2116 matches for " reproduction "
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Underground water affects sexual behavior and gene expression of hormones related to reproduction in blue gourami males  [PDF]
Gad Degani, Gal Levy
Advances in Biological Chemistry (ABC) , 2013, DOI: 10.4236/abc.2013.31016
Abstract:

This study examined the effect of underground water on reproduction- and growth-related hormones in blue gourami males under non-reproductive and reproductive conditions. An increase in the percentage of males building nests under the highest percentage of underground water were compared to fish that maintained a lower percentage of underground water in the first two days. The % Gonado-somatic index (GSI) of males building nests was higher than non- reproductively active males in water containing the lowest concentration of underground water. In non- reproductively active males, brain gonadotropin releasing hormone 1 (GnRH1) and pituitary β subunit of gonadotropins (GtHs) and prolactin (PRL) mRNA levels were significantly higher in males maintained in underground water. In reproductively active males, mRNA levels of brain GnRH1, gonadotropin releasing hormone 3 (GnRH3) and pituitary PRL mRNA levels were significantly higher than males maintained in underground water. Thus, it is suggested that underground water with high salinity and conductivity levels affects the gene expression of repro- duction-related hormones; in reproductively active males, it shortened the duration of nest-building by blue gourami males.

Retrospective reproduction analysis in female reindeer (Rangifer tarandus)
Thrine Moen Heggberget
Rangifer , 2002,
Abstract: Retrospective reproduction analysis has proven a useful study method for many mammal species, but the method has not been used as much in reindeer and caribou studies as it deserves.
Genetic Diversity of the Pepper Pathogen Phytophthora capsici on Farms in the Amazonian High Jungle of Peru  [PDF]
Jon Hulvey, Oscar Hurtado-Gonzalez, Liliana Aragón-Caballero, Daniel Gobena, Dylan Storey, Ledare Finley, Kurt Lamour
American Journal of Plant Sciences (AJPS) , 2011, DOI: 10.4236/ajps.2011.23054
Abstract: Phytophthora capsici is an important oomycete pathogen of Capsicum peppers worldwide. Populations of P. capsici recovered from coastal regions in Peru were previously shown to be dominated by a single clonal lineage referred to as PcPE-1. During 2008, 219 isolates of P. capsici were collected from Capsicum pubescens (Rocoto), C. annum (Pimento), and C. baccatum (Aji) at 9 farms in the Amazonian high jungle in the areas surrounding Oxapampa, and one coastal location, Carabayllo. Two isolates of P. capsici were also recovered from Cyclanthera pedata (Caigua fruit) near one field. All isolates were characterized using a panel of eight single nucleotide polymorphism (SNP) markers that are fixed for heterozygosity in the PcPE-1 lineage. A subset of isolates was also characterized using amplified fragment length polymorphism (AFLP) markers. Nine discreet SNP multi-locus genotypes were identified, and the PcPE-1 lineage was recovered from all of the field sites. Both A1 and A2 mating types were recovered from two sites. The implications of the genotypic diversity and distribution identified in this study are discussed.
Some Models of Reproducing Graphs: I Pure Reproduction  [PDF]
Richard Southwell, Chris Cannings
Applied Mathematics (AM) , 2010, DOI: 10.4236/am.2010.13018
Abstract: Many real world networks change over time. This may arise due to individuals joining or leaving the network or due to links forming or being broken. These events may arise because of interactions between the vertices which occasion payoffs which subsequently determine the fate of the nodes, due to ageing or crowding, or perhaps due to isolation. Such phenomena result in a dynamical system which may lead to complex behaviours, to self-replication, to chaotic or regular patterns, to emergent phenomena from local interactions. They give insight to the nature of the real-world phenomena which the network, and its dynamics, may approximate. To a large extent the models considered here are motivated by biological and social phenomena, where the vertices may be genes, proteins, genomes or organisms, and the links interactions of various kinds. In this, the first paper of a series, we consider the dynamics of pure reproduction models where networks grow relentlessly in a deterministic way.
Some Models of Reproducing Graphs: III Game Based Reproduction  [PDF]
Richard Southwell, Chris Cannings
Applied Mathematics (AM) , 2010, DOI: 10.4236/am.2010.15044
Abstract: Many real world networks change over time. This may arise due to individuals joining or leaving the network or due to links forming or being broken. These events may arise because of interactions between the vertices which occasion payoffs which subsequently determine the fate of the vertices, due to ageing or crowding, or perhaps due to isolation. Such phenomena result in a dynamical system which may lead to complex behaviours, to selfreplication, to chaotic or regular patterns, or to emergent phenomena from local interactions. They hopefully give insight to the nature of the real-world phenomena which the network, and its dynamics, may approximate. To a large extent the models considered here are motivated by biological and social phenomena, where the vertices may be genes, proteins, genomes or organisms, and the links interactions of various kinds. In this, the third paper of a series, we consider the vertices to be players of some game. Offspring inherit their parent’s strategies and vertices which behave poorly in games with their neighbours get destroyed. The process is analogous to the way different kinds of animals reproduce whilst unfit animals die. Some game based systems are analytically tractable, others are highly complex-causing small initial structures to grow and break into large collections of self replicating structures.
Further Properties of Reproducing Graphs  [PDF]
Jonathan Jordan, Richard Southwell
Applied Mathematics (AM) , 2010, DOI: 10.4236/am.2010.15045
Abstract: Many real world networks grow because their elements get replicated. Previously Southwell and Cannings introduced a class of models within which networks change because the vertices within them reproduce. This happens deterministically so each vertex simultaneously produces an offspring every update. These offspring could represent individuals, companies, proteins or websites. The connections given to these offspring depend upon their parent’s connectivity much as a child is likely to interact with their parent’s friends or a new website may copy the links of pre-existing one. In this paper we further investigate one particular model, ‘model 3’, where offspring connect to their parent and parent’s neighbours. This model has some particularly interesting features, including a degree distribution with an interesting fractal-like form, and was introduced independently under the name Iterated Local Transitivity by Bonato et al. In particular we show connections between this degree distribution and the theory of integer partitions and show that this can be used to explain some of the features of the degree distribution; we give exact formulae for the number of complete subgraphs and the global clustering coefficient and we show how to calculate the minimal cycle basis.
Basic biological aspects of Tritrichomonas foetus of re-levance to the treatment of bovines suffering of tricho-moniasis  [PDF]
Newton Soares da Silva, Susane Moreira Machado, Fernando Costa e Silva Filho, Cristina Pacheco-Soares
Open Journal of Animal Sciences (OJAS) , 2011, DOI: 10.4236/ojas.2011.13015
Abstract: Tritrichomonas foetus is a flagellate protozoan and the etiological agent of bovine genital tri-chomoniasis [1], which is an infectious vene- real disease. This parasite is usually found as- sociated with the mucosal surface of the uro- genital tract in females or the male preputial and penile membranes. In females, the clinical ma-nifestations may include abortion, with repe- tition of estrus at irregular intervals, vaginitis, cervicitis, endometritis, and pyometra. Parasi- tized males may have a discharge with small nodules in the preputial membrane. After that, the bulls have no clinical symptoms, and are thus an asymptomatic carrier that may spread the infection. Considering that a bull could cover up to twenty females [2], bovine genital trichomoniasis is a serious medical and veteri- nary problem, with economical repercussion for beef and milk production. As T. foetus is an amitochondrial and aerotolerant organism, en- ergy production under low O2 tension in the protozoan is done via hydrogenosome, which, as the name suggests, is the organelle where H2 is generated [3,4,5]. The molecular machinery of mitochondrial cell death is, therefore, absent in this parasite and the mechanism that activates of cell death program is not clear. This review seeks to understand the characteristics of the protozoan parasite T. foetus in order to propose new therapies for animals suffering from this infectious and contagious agent.
Impact of Awareness on the Spread of Dengue Infection in Human Population  [PDF]
Sunita Gakkhar, Nareshkumar C. Chavda
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.48A020
Abstract:

In this paper, a model is proposed to study the impact of awareness on the dynamics of dengue. It is assumed that due to awareness of the disease some susceptible take necessary precautionary measures to protect themselves from mosquito bite. A threshold is obtained for the stability of the disease-free equilibrium state. The awareness is found to affect the threshold. For the sufficiently large awareness rate, the endemic state does not exist and disease-free state remains globally stable. It is concluded that the increase in the awareness rate decreases the densities of infectious populations of human as well as mosquitoes.

Determining Cognitive Structures and Alternative Conceptions on the Concept of Reproduction (The Case of Pre-Service Biology Teachers)  [PDF]
Hakan Kurt, Gülay Ekici, ?zlem Aksu, Murat Akta?
Creative Education (CE) , 2013, DOI: 10.4236/ce.2013.49083
Abstract:

Reproduction is among basic functions of living beings and one of elementary complex subjects of the biology course. This is complicated for learners to construct cognitive structures on the subject. The aim of the current study is to investigate pre-service biology teachers’ cognitive structures related to “reproduction” through the free word-association test and the drawing-writing technique. As the research design of the study, the qualitative research method was applied. The data were collected from pre-service biology teachers. The free word-association test and the drawing-writing technique were used as data collection instruments. The data were subject to content analysis and divided into categories through coding. With the help of these categories, the cognitive structures of pre-service biology teachers were explained. The data collected through the study were divided into 7 categories (structures required for reproduction, re-production in plants and sections, types of reproduction, insemination, reproduction-inheritance, defining reproduction and its importance, reproductive anatomy). In the categories obtained, it was determined that ample data could be collected using different assessment instruments. On the other hand, it was de- termined that pre-service biology teachers had alternative conceptions related to reproduction. It was observed that the pre-service teachers had imperfect cognitive structures regarding the subject of reproduction. Comprehensive suggestions related to the subject are presented at the end of this article.

The False Problem of the Maintenance of Sex (Review of the Original Approach)  [PDF]
Jose Maria Mancebo Quintana
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.519297
Abstract: We analyze here the keys of the original approach about the twofold cost: the return to the asexuality starting with a mutant female, with the same reproductive capacity than a sexual one, and with double genetic-reproductive success. We propose a new approach in which 1) all individuals in a population have regulatory mechanisms of reproductive mode, and when such change occurs, it happens in all its population at the same time; 2) after a change of reproductive mode in the population there can be variations in average offspring per female, according to the environmental quality; and 3) the genetic-reproductive success of the males and its unequal paternity success are accounted for. Results: The most advantageous reproductive strategy depends on the demographic situation of the population and the degree of the unequal paternity success of males. For harem values observed in nature and in populations with moderate growth rate, stable or decreasing population, the sexual strategy is advantageous. If the population growth rate is high, the asexual strategy is advantageous. In species subject to high demographic fluctuations the best strategy depends on the ability to predict the time of occurrence of the population bottleneck: if predictable, the best strategy is the alternation of generations, if not, permanent parthenogenesis.
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