What I believe about leadership and education : a reflective essay

Communication is the ground work for everything. Without it an administrator cannot effectively move their school forward. However, the school needs a direction to go. When an administrator has a vision, he or she can lead the school in that direction – thus making the school a better place. In order for the school to be effective, it is also helpful to have an administrator that has good organizational skills. Finally, a school is built for instruction. Above all else, an administrator must remember why they are there, to assist the staff in teaching children. The administrator must hold teachers accountable for their instructional practices. Without communication, having a vision, being organized, and being an instructional leader, an administrator will be limited in their impact. When an administrator uses all these elements they will be highly effective with a significant impact on faculty and staff. Administrators.must have many more skills than just these four. However, these are four core elements that are essential for exemplary educational leadership

Toxoplasma gondii Syntaxin 6 is required for vesicular transport between endosomal-like compartments and the Golgi Complex

Apicomplexans are obligate intracellular parasites that invade the host cell in an active process that relies on unique secretory organelles (micronemes, rhoptries and dense granules) localized at the apical tip of these highly polarized eukaryotes. In order for the contents of these specialized organelles to reach their final destination, these proteins are sorted post-Golgi and it has been speculated that they pass through endosomal-like compartments (ELCs), where they undergo maturation. Here, we characterize a Toxoplasma gondii homologue of Syntaxin 6 (TgStx6), a well-established marker for the early endosomes and trans Golgi network (TGN) in diverse eukaryotes. Indeed, TgStx6 appears to have a role in the retrograde transport between ELCs, the TGN and the Golgi, because overexpression of TgStx6 results in the development of abnormally shaped parasites with expanded ELCs, a fragmented Golgi and a defect in inner membrane complex maturation. Interestingly, other organelles such as the micronemes, rhoptries and the apicoplast are not affected, establishing the TGN as a major sorting compartment where several transport pathways intersect. It therefore appears thatToxoplasma has retained a plant-like secretory pathway

Protein trafficking through the endosomal system prepares intracellular parasites for a home invasion

Toxoplasma (toxoplasmosis) and Plasmodium (malaria) use unique secretory organelles for migration, cell invasion, manipulation of host cell functions, and cell egress. In particular, the apical secretory micronemes and rhoptries of apicomplexan parasites are essential for successful host infection. New findings reveal that the contents of these organelles, which are transported through the endoplasmic reticulum (ER) and Golgi, also require the parasite endosome-like system to access their respective organelles. In this review, we discuss recent findings that demonstrate that these parasites reduced their endosomal system and modified classical regulators of this pathway for the biogenesis of apical organelles

Biogenesis of the inner membrane complex is dependent on vesicular transport by the alveolate specific GTPase Rab11B

Apicomplexan parasites belong to a recently recognised group of protozoa referred to as Alveolata. These protists contain membranous sacs (alveoli) beneath the plasma membrane, termed the Inner Membrane Complex (IMC) in the case of Apicomplexa. During parasite replication the IMC is formed de novo within the mother cell in a process described as internal budding. We hypothesized that an alveolate specific factor is involved in the specific transport of vesicles from the Golgi to the IMC and identified the small GTPase Rab11B as an alveolate specific Rab-GTPase that localises to the growing end of the IMC during replication of Toxoplasma gondii. Conditional interference with Rab11B function leads to a profound defect in IMC biogenesis, indicating that Rab11B is required for the transport of Golgi derived vesicles to the nascent IMC of the daughter cell. Curiously, a block in IMC biogenesis did not affect formation of sub-pellicular microtubules, indicating that IMC biogenesis and formation of sub-pellicular microtubules is not mechanistically linked. We propose a model where Rab11B specifically transports vesicles derived from the Golgi to the immature IMC of the growing daughter parasites

The role of clathrin in post-golgi trafficking in toxoplasma gondii

Apicomplexan parasites are single eukaryotic cells with a highly polarised secretory system that contains unique secretory organelles (micronemes and rhoptries) that are required for host cell invasion. In contrast, the role of the endosomal system is poorly understood in these parasites. With many typical endocytic factors missing, we speculated that endocytosis depends exclusively on a clathrin-mediated mechanism. Intriguingly, in Toxoplasma gondii we were only able to observe the endogenous clathrin heavy chain 1 (CHC1) at the Golgi, but not at the parasite surface. For the functional characterisation of Toxoplasma gondii CHC1 we generated parasite mutants conditionally expressing the dominant negative clathrin Hub fragment and demonstrate that CHC1 is essential for vesicle formation at the trans-Golgi network. Consequently, the functional ablation of CHC1 results in Golgi aberrations, a block in the biogenesis of the unique secretory microneme and rhoptry organelles, and of the pellicle. However, we found no morphological evidence for clathrin mediating endocytosis in these parasites and speculate that they remodelled their vesicular trafficking system to adapt to an intracellular lifestyle

Cathepsin L occupies a vacuolar compartment and is a protein maturase within the endo/exocytic system of Toxoplasma gondii

Regulated exocytosis allows the timely delivery of proteins and other macromolecules precisely when they are needed to fulfil their functions. The intracellular parasite Toxoplasma gondii has one of the most extensive regulated exocytic systems among all unicellular organisms, yet the basis of protein trafficking and proteolytic modification in this system is poorly understood. We demonstrate that a parasite cathepsin protease, TgCPL, occupies a newly recognized va cuolar c ompartment (VAC) that undergoes dynamic fragmentation during T. gondii replication. We also provide evidence that within the VAC or late endosome this protease mediates the proteolytic maturation of proproteins targeted to micronemes, regulated secretory organelles that deliver adhesive proteins to the parasite surface during cell invasion. Our findings suggest that processing of microneme precursors occurs within intermediate endocytic compartments within the exocytic system, indicating an extensive convergence of the endocytic and exocytic pathways in this human parasite.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/79312/1/j.1365-2958.2010.07181.x.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/79312/2/MMI_7181_sm_FigS1-8.pd

Rapport III.11. L'expérience hongroise en matière de lutte contre les inondations

In the first part of this article, attention is drawn to the tremendous importance of flood control and protection in Hungary, because of the country’s geographical features, and to the need for development of flood defences, followed by a description of the basic principles of the economic calculations involved in the determination of the rate of development. These calculations are based on recorded direct and indirect damage, estimated damage prevented, and the measured saving in flood-defence costs. In the second part, it is shown from experience of major floods during the last fifteen years various hydraulic, biological and chemical effects have caused visible signs of "ageing" of levee materials and the subsoil, resulting in a lower resistance to water penetration. Wherever possible, therefore, the levees should be strengthened by the u hydromechanisation n process. The third part describes the Hungarian flood control and protection organisation and its operation ; its achievements in dealing with the extraordinary Danube flood in 1965 are quoted as an example of its scope.Après avoir mis en lumière l’importance extraordinaire de la défense contre les crues dans les conditions géographiques de la Hongrie et la nécessité de développer les ouvrages de défense, la première partie expose les principes fondamentaux des calculs économiques à effectuer pour déterminer le rythme du développement. Les calculs sont basés sur le relevé des dommages directs et indirects qui se sont produits, sur l’estimation des dommages écartés et sur la mesure de la diminution des frais de la défense. Dans la seconde partie, il est démontré, sur la base des expériences des grandes crues des dernières 15 années, qu’à la suite des effets hydrauliques, biologiques et chimiques, il se révèle dans les matériaux des levées et du sous-sol des signes de «vieillissement» : leur résistance à la pénétration de l’eau a diminué. Le renforcement des levées doit s’exécuter, en tenant compte de ce fait, autant que possible par le procédé de l’hydromécanisation. La troisième partie présente l’organisation hongroise de la défense contre les crues, ainsi que son fonctionnement, et illustre ses proportions avec les données de la défense contre la crue extraordinaire du Danube en 1965.Karaszi K., Breinich M., Ihrig D. Rapport III.11. L'expérience hongroise en matière de lutte contre les inondations. In: La prévision des crues et la protection contre les inondations. Dixièmes journées de l'hydraulique. Paris, 5, 6 et 7 juin 1968. Tome 3, 1969