A Model for the Development of the Rhizobial and Arbuscular Mycorrhizal Symbioses in Legumes and Its Use to Understand the Roles of Ethylene in the Establishment of these two Symbioses

We propose a model depicting the development of nodulation and arbuscular mycorrhizae. Both processes are dissected into many steps, using Pisum sativum L. nodulation mutants as a guideline. For nodulation, we distinguish two main developmental programs, one epidermal and one cortical. Whereas Nod factors alone affect the cortical program, bacteria are required to trigger the epidermal events. We propose that the two programs of the rhizobial symbiosis evolved separately and that, over time, they came to function together. The distinction between these two programs does not exist for arbuscular mycorrhizae development despite events occurring in both root tissues. Mutations that affect both symbioses are restricted to the epidermal program. We propose here sites of action and potential roles for ethylene during the formation of the two symbioses with a specific hypothesis for nodule organogenesis. Assuming the epidermis does not make ethylene, the microsymbionts probably first encounter a regulatory level of ethylene at the epidermis–outermost cortical cell layer interface. Depending on the hormone concentrations there, infection will either progress or be blocked. In the former case, ethylene affects the cortex cytoskeleton, allowing reorganization that facilitates infection; in the latter case, ethylene acts on several enzymes that interfere with infection thread growth, causing it to abort. Throughout this review, the difficulty of generalizing the roles of ethylene is emphasized and numerous examples are given to demonstrate the diversity that exists in plants

Mandibular reconstruction with vascularised bone flaps: a systematic review over 25 years

To explore the techniques for mandibular reconstruction with composite free flaps and their outcomes, we systematically reviewed reports published between 1990 and 2015. A total of 9499 mandibular defects were reconstructed with 6178 fibular, 1380 iliac crest, 1127 composite radial, 709 scapular, 63 serratus anterior and rib, 32 metatarsal, and 10 lateral arm flaps including humerus. The failure rate was higher for the iliac crest (6.2%, 66/1059) than for fibular, radial, and scapular flaps combined (3.4%, 202/6018) (p<0.001). We evaluated rates of osteotomy, non-union, and fistulas. Implant-retained prostheses were used most often for rehabilitation after reconstruction with iliac crest (44%, 100/229 compared with 26%, 605/2295 if another flap was used) (p<0.001). There were no apparent changes in the choice of flap or in the complications reported. Although we were able to show some significant differences relating to the types of flap used, we were disappointed to find that fundamental outcomes such as the need for osteotomy, and rates of non-union and fistulas were under-reported. This review shows the need for more comprehensive and consistent reporting of outcomes to enable the comparison of different techniques for similar defects

Evaluación de la comprensión sobre Tablas Estadísticas en estudiantes de Educación Primaria

Este trabajo da cuenta de la organización y estructura del resultado de la respuesta observada sobre tablas estadísticas en estudiantes de Educación Primaria de escuelas municipalizadas en la provincia de Osorno-Chile. Se aplicó una prueba con cuatro preguntas abiertas a una muestra de 233 estudiantes de tercero y sexto nivel. Las respuestas fueron clasificadas según un continuo que va desde la incompetencia a la maestría: la capacidad, operaciones implicadas, consistencia y conclusiones. Los resultados muestran que las respuestas de los estudiantes se agrupan, mayoritariamente, en el enfoque de aprendizaje superficial, esto significa que, aunque entrega datos relevantes lo hace en forma aislada, los ordenan pero, falla en la conexión entre ellos. Se observó que no hay diferencias significativas entre la estructura y organización de las respuestas que elaboran los estudiantes de tercero y sexto año

The Biochemical and Cellular Basis for Nutraceutical Strategies to Attenuate Neurodegeneration in Parkinson’s Disease

Future therapeutic intervention that could effectively decelerate the rate of degeneration within the substantia nigra pars compacta (SNc) could add years of mobility and reduce morbidity associated with Parkinson’s disease (PD). Neurodegenerative decline associated with PD is distinguished by extensive damage to SNc dopaminergic (DAergic) neurons and decay of the striatal tract. While genetic mutations or environmental toxins can precipitate pathology, progressive degenerative succession involves a gradual decline in DA neurotransmission/synaptic uptake, impaired oxidative glucose consumption, a rise in striatal lactate and chronic inflammation. Nutraceuticals play a fundamental role in energy metabolism and signaling transduction pathways that control neurotransmission and inflammation. However, the use of nutritional supplements to slow the progression of PD has met with considerable challenge and has thus far proven unsuccessful. This review re-examines precipitating factors and insults involved in PD and how nutraceuticals can affect each of these biological targets. Discussed are disease dynamics (Sections 1 and 2) and natural substances, vitamins and minerals that could impact disease processes (Section 3). Topics include nutritional influences on α-synuclein aggregation, ubiquitin proteasome function, mTOR signaling/lysosomal-autophagy, energy failure, faulty catecholamine trafficking, DA oxidation, synthesis of toxic DA-quinones, o-semiquinones, benzothiazolines, hyperhomocyseinemia, methylation, inflammation and irreversible oxidation of neuromelanin. In summary, it is clear that future research will be required to consider the multi-faceted nature of this disease and re-examine how and why the use of nutritional multi-vitamin-mineral and plant-based combinations could be used to slow the progression of PD, if possible

The measurement of bilingual abilities: central challenges

In this handbook chapter I analyse the concept of bilingual abilities. Bilinguals vary widely in what they can do with their languages or in the ways in which they use their languages on a daily basis. This means that there is a great deal of variability in what the term covers. While many researchers subscribe to the holistic view of bilingualism, in the academic literature bilinguals are still often described in negative terms as having a "deficit" in one or another subsystem of their languages. The key aim of this chapter is to identify what makes individuals with bilingual abilities unique speaker-hearers in their own right, avoiding the fractional view of bilingualism, and how these abilities can be measured

Language endangerment and language documentation in Africa

Non peer reviewe