Gardens as Science Learning Contexts Across Educational Stages: Learning Assessment Based on Students' Graphic Representations

The educational use of daily-life contexts is considered a valuable strategy to promote meaningful science learning, since it facilitates the establishment of connections between previous knowledge, personal interests, and new learning. The aim of this work is to provide evidence to support the presence of gardens at educational centers, by assessing key science topics whose learning is promoted at the pre-school, primary, secondary, and university stages. To this end, we analyzed the paired graphic representations of "a garden" that students drew both before and after their participation in a garden-based learning program. Firstly, we obtained the frequency of appearance of every represented element, and afterward characterized the level of change between paired graphic representations. Sample size was of 24-19-25-29 pairs per stage, respectively. Across all stages, an overall improvement in students' graphic expression was observed, which can be attributed to their experience in the space. At the pre-school stage, the garden favored the establishment of some simple cause-effect relationships which were consolidated at the primary stage, and provided a climate of motivation and affectivity that was evident in the final drawings, given the enormous quantity of details represented, the level of the finished product, and the careful combination and variety of colors. The presence of elements related to water notably increased in final graphic representations from pre-school, primary, and secondary education, thus evidencing that the use of gardens facilitates an approach to responsible water management. At the university stage, students initially demonstrated good knowledge of conventional agriculture, while the gardening experience -which was based on permaculture practices- helped evolve their ideas toward an alternative model of cultivation. The most prevalent science learning across all stages was related to plant knowledge, particularly to their anatomical traits and diversity. Finally, the role of educational gardens as models for students was evidenced, which suggests the importance of teachers and institutions carefully considering which model to offer. Overall, our results support the legitimacy of incorporating gardens to educational centers, particularly for promoting contact with live plants and plant knowledge, and potentially for promoting contact with garden fauna and activities oriented toward learning about it.

Positive supercoiling of mitotic DNA drives decatenation by topoisomerase II in eukaryotes

DNA topoisomerase II completely removes DNA intertwining, or catenation, between sister chromatids before they are segregated during cell division. How this occurs throughout the genome is poorly understood. We demonstrate that in yeast, centromeric plasmids undergo a dramatic change in their topology as the cells pass through mitosis. This change is characterized by positive supercoiling of the DNA and requires mitotic spindles and the condensin factor Smc2. When mitotic positive supercoiling occurs on decatenated DNA, it is rapidly relaxed by topoisomerase II. However, when positive supercoiling takes place in catenated plasmid, topoisomerase II activity is directed toward decatenation of the molecules before relaxation. Thus, a topological change on DNA drives topoisomerase II to decatenate molecules during mitosis, potentially driving the full decatenation of the genome.

Physical linkages between sister chromatids and their removal during yeast chromosome segregation

The fidelity of chromosome inheritance is of paramount importance to all living organisms. In eukaryotic cells, the strategy to ensure physical segregation of chromosomes to daughter cells relies on two basic steps ordered in time: an initial linkage, or cohesion, of sister chromatids and its timely and complete dissolution during anaphase. The current view is that these two basic steps are accomplished around the regulation of a protein complex called cohesin that serves as "clamp brackets" distributed at intervals throughout the genome. However, many of the DNA metabolic activities during interphase also produce physical linking of chromatids. For example, during replication, intertwines between sister chromatids are formed. Here, we review our understanding of the processes that generate physical linkages between chromatids and discuss potential mechanisms that are involved in the removal of such obstacles to the complete physical separation of chromatids at anaphase.

Quantification of ovarian follicles in bluefin tuna Thunnus thynnus by two stereological methods

The numbers of different types of ovarian follicles (developing, degenerating and postovulatory follicles) were estimated in bluefin tuna Thunnus thynnus using two stereological procedures: the model-based method of Weibel & Gomez, which has become a tool of broad application in the quantification of oocytes in fishes, and the assumption-free 'disector' (sic) method of Sterio. The estimates of developing follicles (follicles containing lipid-stage, vitellogenic and migratory-nucleus oocytes) made by the model-based method tended to be lower than those obtained with the disector, though significant differences were not observed except for vitellogenic follicles. Counts of atretic follicles by the model-based method were higher than those made using the disector, the differences being remarkable between both techniques, particularly in the case of beta-atresia, where the statistical analysis indicated significantly unequal estimations with the two methods. In contrast, the amount of postovulatory follicles estimated by the disector, which would stand for the realized batch fecundity, was somewhat larger than that calculated with the model-based method.

[Continuous quality improvement in the control of the type2 diabetes in Navarra. GEDAPSNA study 1996]

Diabetes mellitus type 2 constitutes one of the principal public health problems today, representing an important burden on care and involving extremely high economic costs, both direct and indirect. To provide an adequate response from the different public health systems, the St. Vincent Declaration was drawn up containing certain recommendations on the protocol of care and the carrying out of controls of continuous quality improvement, since it is a chronic pathology that requires a proactive health policy, which prevents, and provides early detection of its complications. In the present work we set out the results of the first study carried out in Navarra on the indicators of quality in the care provided to diabetics in Primary Health care, carried out by the Study Group on Diabetes Mellitus in Primary Care (GEDAPSNA). The study was made of an aleatory sample of 496 patients, by means of gathering data about their clinical records for the year 1996. 12 process indicators and 12 indicators of intermediate and final results were used. The results detect some important deficiencies that require early intervention: lack of exploration and management of the lesions that make up so-called diabetic foot; low achievement of results in the control of arterial hypertension in this group of patients; and absence of exploration of the lesions of the fundus of the eye in more than 50% of type 2 diabetics.