Jesús Martínez-Cruz

The Podosphaera xanthii haustorium, the fungal Trojan horse of cucurbit-powdery mildew interactions.

The powdery mildew fungi are obligate biotrophic plant pathogens that develop a specialized structure for parasitism termed haustorium, which is responsible for nutrient uptake and factor exchange with the plant. In this work, we present a detailed microscopy analysis of the haustoria of the cucurbit powdery mildew fungus Podosphaera xanthii, a major limiting factor for cucurbit production worldwide. Despite being located inside plant epidermal cells, transmission electron microscopy (TEM) analysis showed the characteristic highly irregular outline of the extrahaustorial membrane that separates the extrahaustorial matrix of haustoria from the cytoplasm of the plant cell. TEM analysis also revealed the presence of some vesicles and electron-dense plaques of material surrounding the haustoria. In confocal microscopy analysis and aniline blue staining we found a positive correlation between haustorial development and deposition of callose, which is distributed as plaques around haustorial complex. In this study, a method for the isolation of P. xanthii haustoria was also adapted, which permitted the analysis of the formation of haustorial lobes and the visualization of vacuoles and the pool of vesicles inside the haustorial complex. Our findings suggested that the haustorial lobes were responsible for vesicular trafficking and most likely act as the main mediators of the fungus-plant dialogue. All of these findings were integrated into a model of the P. xanthii-host cellular interactions.

Reducing the Impact of Massive Multiplayer Online Games on the Internet Using SCTP

Games are on the Internet to stay. Their popularity and use are growing every day, and some genres such as the Massive Multiplayer Online Role-Playing Games (MMORPGs) have become an important source of network traffic having several thousands of simultaneous players at any one time. These kinds of games constitute a real challenge for developers but also for Internet service providers due to their high requirements of bandwidth and hardware resources. Therefore, it is really important for MMORPGs to be supported by high-performance network code. We show how these games can benefit from the new transport protocol in the TCP/IP stack, the Stream Control Transmission Protocol (SCTP) which can increase the overall efficiency of a game protocol in terms of latency and jitter, along with extra savings in processing time for packet management. Both of these are important details for players game experience and for server resource provisioning, respectively.