Resistance of autotetraploids of grapevine rootstock cultivars to phylloxera (Daktulosphaira vitifoliae FITCH)

Resistance of colchicine-induced autotetraploids of four grapevine rootstock cultivars (Riparia Gloire de Montpellier, Rupestris St. George, Couderc 3309 and Kober 5BB) to phylloxera (Daktulosphaira vitifoliae FITCH) was evaluated using the aseptic co-culture technique of root segments and phylloxera in a petri dish, and compared with those of the original diploid and Cabernet Franc (Vitis vinifera L.). None or very few phylloxera nymphs grew to adults on the root of the rootstock cultivars and their autotetrapolids whereas 26.8 % of the eggs grew to adults on the roots of Cabernet Franc. Resistance of Riparia Gloire de Mont-pellier, Rupestris St. George, Couderc 3309 and their autotetraploids to phylloxera was also tested by planting in a phylloxera-infested vineyard and compared with that of Kyoho, a tetraploid table grape cultivar (V. vinifera x V. labrusca Bailey). The formation of galls on the root tips of tetraploid rootstock cultivars was not increased significantly as compared to that on their original diploid plants whereas galls were formed on 52.9% of Kyoho root tips examined. These results show that the autotetraploid rootstock cultivars used in this study had high resistance to phylloxera, thus they were not different from the original diploids.

Comparison of the growth and leaf mineral concentrations between three grapevine rootstocks and their corresponding tetraploids inoculated with an arbuscular mycorrhizal fungus Gigaspora margarita

Effects of the arbuscular mycorrhizal (AM) fungus Gigaspora margarita BECKER and HALL on growth and leaf mineral concentrations of the tetraploid grapevine rootstocks Gloire de Montpellier (Gloire, Vitis riparia MICHX.), Rupestris St. George (St. George, V. rupestris SCHEELE), and Couderc 3309 (3309, V. riparia x V. rupestris) were compared with those of their corresponding diploids. The percentage of AM infection in the inoculated tetraploid grapevines of each rootstock was as high (above 90 %) as in the inoculated diploids. Shoot and root growth in the inoculated grapevines of each tetraploid was significantly higher than that in the non-inoculated grapevines. For the original diploid rootstocks, almost the same shoot and root growth was observed regardless of inoculation. Tetraploid and diploid rootstocks with AM fungi-inoculation had significantly higher P concentrations in the leaves than the non-inoculated grapevines, but tetraploid grapevines with AM fungi-inoculation had lower Ca and Mg concentrations. The tetraploid grapevines with thicker roots and more compact root systems were considered to depend more on arbuscular mycorrhizas than the original diploid rootstock cultivars.

Dynamic Regulation of Proteasome Expression

The 26S proteasome is a multisubunit complex that catalyzes the degradation of ubiquitinated proteins. The proteasome comprises 33 distinct subunits, all of which are essential for its function and structure. Proteasomes are necessary for various biological processes in cells; therefore, precise regulation of proteasome expression and activity is essential for maintaining cellular health and function. Two decades of research revealed that transcription factors such as Rpn4 and Nrf1 control expression of proteasomes. In this review, we focus on the current understanding and recent findings on the mechanisms underlying the regulation of proteasome expression, as well as the translational regulation of proteasomes

Inhibition of 26S proteasome activity by α-synuclein is mediated by the proteasomal chaperone Rpn14/PAAF1

\ua9 2024 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.Parkinson\u27s disease (PD) is characterized by aggregation of α-synuclein (α-syn) into protein inclusions in degenerating brains. Increasing amounts of aggregated α-syn species indicate significant perturbation of cellular proteostasis. Altered proteostasis depends on α-syn protein levels and the impact of α-syn on other components of the proteostasis network. Budding yeast Saccharomyces cerevisiae was used as eukaryotic reference organism to study the consequences of α-syn expression on protein dynamics. To address this, we investigated the impact of overexpression of α-syn and S129A variant on the abundance and stability of most yeast proteins using a genome-wide yeast library and a tandem fluorescent protein timer (tFT) reporter as a measure for protein stability. This revealed that the stability of in total 377 cellular proteins was altered by α-syn expression, and that the impact on protein stability was significantly enhanced by phosphorylation at Ser129 (pS129). The proteasome assembly chaperone Rpn14 was identified as one of the top candidates for increased protein stability by expression of pS129 α-syn. Elevated levels of Rpn14 enhanced the growth inhibition by α-syn and the accumulation of ubiquitin conjugates in the cell. We found that Rpn14 interacts physically with α-syn and stabilizes pS129 α-syn. The expression of α-syn along with elevated levels of Rpn14 or its human counterpart PAAF1 reduced the proteasome activity in yeast and in human cells, supporting that pS129 α-syn negatively affects the 26S proteasome through Rpn14. This comprehensive study into the alternations of protein homeostasis highlights the critical role of the Rpn14/PAAF1 in α-syn-mediated proteasome dysfunction

Space Asymmetry Directs Preferential Sperm Entry in the Absence of Polarity in the Mouse Oocyte

Knowledge about the mechanism that establishes embryonic polarity is fundamental in understanding mammalian development. In re-addressing several controversial claims, we recently proposed a model in which mouse embryonic polarity is not specified until the blastocyst stage. Before fertilization, the fully differentiated oocyte has been characterized as “polarized,” and we indeed observed that the sperm preferentially enters the polar body half. Here we show that preferential sperm entry is not due to an intrinsic polarity of the oocyte, since fertilization takes place uniformly when the zona pellucida is removed. We suggest that the term “asymmetry” denotes morphological differences, whereas “polarity” in addition implies developmental consequences. Thus, the mouse oocyte can be considered “asymmetric” but “non-polarized.” The penetration through the zona pellucida is also random, and a significant proportion of sperm binds to the oocyte membrane at a point distant from the zona penetration site. Time-lapse recordings confirmed that sperm swim around the perivitelline space before fertilization. Experimental enlargement of the perivitelline space in the non-polar body half increased the regional probability of fertilization. Based on these experiments, we propose a model in which the space asymmetry exerted by the first polar body and the zona pellucida directs sperm entry preferentially to the polar body half, with no need for oocyte polarity