Diplospory and obligate apomixis in Miconia albicans (Miconieae, Melastomataceae) and an embryological comparison with its sexual congener M-chamissois

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Apomixis, or asexual reproduction through seeds, has been reported for species of the tribe Miconieae, Melastomataceae, but details of the process have yet to be described. We analyzed and compared sporogenesis and gametogenesis in the apomictic Miconia albicans and the sexual M. chamissois. The results point to some differences between species, which were related to the apomictic process. In M. albicans microsporogenesis, problems during meiosis and degeneration of its products led to total pollen sterility, while M. chamissois presented normal bicellular pollen grains in the mature anther. The absence or abnormality of meiosis in M. albicans megasporogenesis led to the formation of an unreduced embryo sac and also to egg cell parthenogenesis, which gave rise to the apomictic embryo. Embryo and endosperm development were autonomous, resulting in seeds and fruits independent of pollination and fertilization. Thus, in this species, apomixis can be classified as diplosporic and obligate. In contrast, meiosis was as expected in the sexual M. chamissois, and led to the development of a reduced embryo sac. Despite the divergent pathways, many embryological characteristics were similar between the studied species and other Melastomataceae and they seem to be conservative character states for the family.299712531262Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Variation in Weed Seed Fate Fed to Different Holstein Cattle Groups

Weed seeds may maintain their viability when passing through the digestive tract of cattle and can be therefore dispersed by animal movement or the application of manure. Whether different cattle types of the same species can cause differential weed seed fate is largely unknown to us particularly under non-grazed systems similar to Holstein-Friesian dairy farming. We investigated the effect on the seed survival of four weed species in the digestive tracts of four groups of Holstein cattle: lactating cows, feedlot male calves, dry cows and growing heifers. The weed species used were Cuscuta campestris, Polygonum aviculare, Rumex crispus and Sorghum halepense. Cattle excretion was sampled for recovery and viability of seeds at four 24 hourly intervals after seed intake. The highest seed recovery occurred two days after seed intake in all cattle groups. Averaged over weed species, dry and lactating cows had the lowest and highest seed recovery of 36.4% and 74.4% respectively. No significant differences were observed in seed recovery of the four weed species when their seeds were fed to dry cows. Based on a power model fitted to seed viability data, the estimated time to 50% viability loss after seed intake, over all cattle groups ranged from 65 h (R. crispus) to 76 h (P. aviculare). Recovered seeds from the dung of feedlot male calves showed the highest mortality among cattle groups. Significant correlation was found between seed viability and ruminal pH (r = 0.86; P<0.05). This study shows that management programs aiming to minimize weed infestation caused by livestock should account for the variation amongst cattle groups in seed persistence. Our findings can be used as a guideline for evaluating the potential risk of the spread of weeds via the application of cattle manure

Restoration of invaded Cape Floristic Region riparian systems leads to a recovery in foliage-active arthropod alpha- and beta-diversity

The Cape Floristic Region of South Africa is a global biodiversity hotspot threatened by invasive alien plants (IAPs). We assessed the effect of plant invasions, and their subsequent clearing, on riparian arthropod diversity. Foliage-active arthropod communities were collected from two native and one invasive alien tree species. Alpha- and beta- diversity of their associated arthropod communities were compared between near pristine, Acacia-invaded and restored sites. Arthropod alpha-diversity at near pristine sites was higher than at restored sites, and was lowest at invaded sites. This was true for most arthropod taxonomic groups associated with all native tree species and suggests a general trend towards recovery in arthropod alpha-diversity after IAP removal. Overall, arthropod species turnover among sites was significantly influenced by plant invasions with communities at near pristine sites having higher turnover than those at restored and invaded sites. This pattern was not evident at the level of individual tree species. Although arthropod community composition was significantly influenced by plant invasions, only a few significant differences in arthropod community composition could be detected between restored and near pristine sites for all tree species and arthropod taxonomic groups. Assemblage composition on each tree species generally differed between sites with similar degrees of plant invasion indicating a strong turnover of arthropod communities across the landscape. Results further suggest that both arthropod alpha- and beta- diversity can recover after IAP removal, given sufficient time, but catchment signatures must be acknowledged when monitoring restoration recovery.The DST/NRF Centre of Excellence in Tree Health Biotechnologyhttp://link.springer.com/journal/108412017-02-28hb2016Microbiology and Plant Patholog

Translating Dysphagia Evidence into Practice While Avoiding Pitfalls: Assessing Bias Risk in Tracheostomy Literature.

Critically ill patients who require a tracheostomy often have dysphagia. Widespread practice guidelines have yet to be developed regarding the acute assessment and management of dysphagia in patients with tracheostomy. In order for clinicians to base their practice on the best available evidence, they must first assess the applicable literature and determine its quality. To inform guideline development, our objective was to assess literature quality concerning swallowing following tracheostomy in acute stages of critical illness in adults. Our systematic literature search (published previously) included eight databases, nine gray literature repositories and citation chasing. Using inclusion criteria determined a priori, two reviewers, blinded to each other, conducted an eligibility review of identified citations. Patients with chronic tracheostomy and etiologies including head and/or neck cancer diagnoses were excluded. Four teams of two reviewers each, blinded to each other, assessed quality of included studies using a modified Cochrane Risk of Bias tool (RoB). Disagreements were resolved by consensus. Data were summarized descriptively according to study design and RoB domain. Of 6,396 identified citations, 74 studies met our inclusion criteria. Of those, 71 were observational and three were randomized controlled trials. Across all studies, the majority (> 75%) had low bias risk with: participant blinding, outcome reporting, and operationally defined outcomes. Areas requiring improvement included assessor and study personnel blinding. Prior to translating the literature into practice guidelines, we recommend attention to study quality limitations and its potential impact on study outcomes. For future work, we suggest an iterative approach to knowledge translation