Moramonas marocensis gen. nov., sp. nov.: a jakobid flagellate isolated from desert soil with a bacteria-like,but bloated mitochondrial genome

A new jakobid genus has been isolated from Moroccan desert soil. The cyst-forming protist Moramonas marocensis gen. nov., sp. nov. has two anteriorly inserted flagella of which one points to the posterior cell pole accompanying the ventral feeding groove and is equipped with a dorsal vane—a feature typical for the Jakobida. It further shows a flagellar root system consisting of singlet microtubular root, left root (R1), right root (R2) and typical fibres associated with R1 and R2. The affiliation of M. marocensis to the Jakobida was confirmed by molecular phylogenetic analyses of the SSU rRNA gene, five nuclear genes and 66 mitochondrial protein-coding genes. The mitochondrial genome has the high number of genes typical for jakobids, and bacterial features, such as the four-subunit RNA polymerase and Shine–Dalgarno sequences upstream of the coding regions of several genes. The M. marocensis mitochondrial genome encodes a similar number of genes as other jakobids, but is unique in its very large genome size (greater than 264 kbp), which is three to four times higher than that of any other jakobid species investigated yet. This increase seems to be due to a massive expansion in non-coding DNA, creating a bloated genome like those of plant mitochondria.     

Predictions of COVID-19 dynamics in the UK: Short-term forecasting and analysis of potential exit strategies

Efforts to suppress transmission of SARS-CoV-2 in the UK have seen non-pharmaceutical interventions being invoked. The most severe measures to date include all restaurants, pubs and cafes being ordered to close on 20th March, followed by a “stay at home” order on the 23rd March and the closure of all non-essential retail outlets for an indefinite period. Government agencies are presently analysing how best to develop an exit strategy from these measures and to determine how the epidemic may progress once measures are lifted. Mathematical models are currently providing short and long term forecasts regarding the future course of the COVID-19 outbreak in the UK to support evidence-based policymaking. We present a deterministic, age-structured transmission model that uses real-time data on confirmed cases requiring hospital care and mortality to provide up-to-date predictions on epidemic spread in ten regions of the UK. The model captures a range of age-dependent heterogeneities, reduced transmission from asymptomatic infections and produces a good fit to the key epidemic features over time. We simulated a suite of scenarios to assess the impact of differing approaches to relaxing social distancing measures from 7th May 2020 on the estimated number of patients requiring inpatient and critical care treatment, and deaths. With regard to future epidemic outcomes, we investigated the impact of reducing compliance, ongoing shielding of elder age groups, reapplying stringent social distancing measures using region based triggers and the role of asymptomatic transmission. We find that significant relaxation of social distancing measures from 7th May onwards can lead to a rapid resurgence of COVID-19 disease and the health system being quickly overwhelmed by a sizeable, second epidemic wave. In all considered age-shielding based strategies, we projected serious demand on critical care resources during the course of the pandemic. The reintroduction and release of strict measures on a regional basis, based on ICU bed occupancy, results in a long epidemic tail, until the second half of 2021, but ensures that the health service is protected by reintroducing social distancing measures for all individuals in a region when required. Our work confirms the effectiveness of stringent non-pharmaceutical measures in March 2020 to suppress the epidemic. It also provides strong evidence to support the need for a cautious, measured approach to relaxation of lockdown measures, to protect the most vulnerable members of society and support the health service through subduing demand on hospital beds, in particular bed occupancy in intensive care units.     

Oral iron and the bioavailability of zinc.

The oral bioavailability of zinc was studied in nonpregnant adults before and 24 hours after two weeks of oral supplementation with iron and folic acid. Bioavailability was greatly reduced, and the shape of the plasma curves suggested that this was due to impairment of the intestinal absorption of zinc. The findings suggest that the reduced bioavailability of zinc occurs because of interelement competition in the bowel wall. This might induce zinc depletion.     

A Lack of Parasitic Reduction in the Obligate Parasitic Green Alga Helicosporidium

The evolution of an obligate parasitic lifestyle is often associated with genomic reduction, in particular with the loss of functions associated with increasing host-dependence. This is evident in many parasites, but perhaps the most extreme transitions are from free-living autotrophic algae to obligate parasites. The best-known examples of this are the apicomplexans such as Plasmodium, which evolved from algae with red secondary plastids. However, an analogous transition also took place independently in the Helicosporidia, where an obligate parasite of animals with an intracellular infection mechanism evolved from algae with green primary plastids. We characterised the nuclear genome of Helicosporidium to compare its transition to parasitism with that of apicomplexans. The Helicosporidium genome is small and compact, even by comparison with the relatively small genomes of the closely related green algae Chlorella and Coccomyxa, but at the functional level we find almost no evidence for reduction. Nearly all ancestral metabolic functions are retained, with the single major exception of photosynthesis, and even here reduction is not complete. The great majority of genes for light-harvesting complexes, photosystems, and pigment biosynthesis have been lost, but those for other photosynthesis-related functions, such as Calvin cycle, are retained. Rather than loss of whole function categories, the predominant reductive force in the Helicosporidium genome is a contraction of gene family complexity, but even here most losses affect families associated with genome maintenance and expression, not functions associated with host-dependence. Other gene families appear to have expanded in response to parasitism, in particular chitinases, including those predicted to digest the chitinous barriers of the insect host or remodel the cell wall of Helicosporidium. Overall, the Helicosporidium genome presents a fascinating picture of the early stages of a transition from free-living autotroph to parasitic heterotroph where host-independence has been unexpectedly preserved.     

Evidence for diet partitioning among three coexisting native freshwater fishes in South Africa's Cape Fold Ecoregion

The partitioning of limited resources commonly explains how different species can coexist within the same ecological community. In this 2010 study, the diets of three coexisting freshwater fishes (Cape galaxias Galaxias zebratus, n = 27; Cape kurper Sandelia capensis, n = 60; Breede River redfin Pseudobarbus burchelli, n = 77) were characterised and compared in three headwater streams in South Africa's Cape Fold Ecoregion using gut contents and stable isotope analyses. These data were analysed to ascertain whether the three species exploit distinct trophic niches. Both approaches provided evidence that these species occupy different trophic niches, though with some overlap. However, dietary differences among sites were not consistent and were probably influenced by site-specific factors like resource availability. Pseudobarbus burchelli had a broader niche breadth at Tierkloof Stream than the other two species, but not at Waaihoek or Tierstel Streams. Our results also suggest that P. burchelli consumed a more omnivorous diet than do the other two species, whereas S. capensis occupied a higher trophic position than the other two species and consumed vertebrates. Our findings suggest that these species occupy non-equivalent feeding niches in Cape Fold Ecoregion headwater streams, and that diet partitioning might facilitate their coexistence in these systems.     

LESSARDIA ELONGATA GEN. ET SP. NOV. (DINOFLAGELLATA,PERIDINIALES, PODOLAMPACEAE) AND THE TAXONOMIC POSITION OF THE GENUS ROSCOFFIA1

We investigate an organism that closely resembles the nonphotosynthetic dinoflagellate “Gymnodinium elongatum” Hope 1954 using EM and molecular methods. Cells are 20–35 μm long, 10 μm wide, biconical, transparent, and have a faint broad girdle. Thecal plates are thin but present (plate formula Po Pi CP 3′ 1–2A 5″ 3C 6S 4? 3″″). With the exception of one feature, the presence of three antapical plates, the amphiesmal arrangement of this species is consistent with that of the order Peridiniales, family Podolampaceae; it is not at all consistent with the characteristics of the genus Gymnodinium. On the basis of these ultrastructural findings, we establish a new genus, Lessardia, and a new species, Lessardia elongata Saldarriaga et Taylor. Molecular phylogenetic analyses were performed using the small subunit rRNA genes of L. elongata as well as Roscoffia capitata, a member of a genus of uncertain systematic position that has been postulated to be related to the Podolampaceae. These analyses place Lessardia and Roscoffia as sister lineages within the so‐called GPP complex. Thecal plate arrangements led us to expand the family Podolampaceae to include the genus Lessardia and, in combination with new molecular results, to propose a close relationship between the Podolampaceae and Roscoffia. Within this lineage, Lessardia and Roscoffia appear to have retained a number of ancestral characters: Roscoffia still has a well‐developed cingulum, a feature absent in all members of the Podolampaceae, and Lessardia has more than one antapical plate, a character reminiscent of some members of the family Protoperidiniaceae.     

The ecological integrity of the lower Olifants River,Limpopo province,South Africa: 2009–2015 – Part B: Tributaries of the Olifants River

Monitoring on the Lowveld reaches of the Olifants River, Limpopo River System, and its Steelpoort, Blyde, Klaserie and Selati tributaries was initiated in 2009. Analysis of the 2009–2015 data from four Olifants River sites showed deterioration in the river’s ecological condition between where it enters the Lowveld and where it enters the Kruger National Park, with a slight recovery within the Kruger National Park. Physico-chemical, aquatic macroinvertebrate and fish data collected in 2009–2015 at six sites on the Steelpoort, Blyde, Klaserie and Selati tributaries of the Olifants River corroborated the ecological condition of these tributaries. The Selati was the most polluted and was in a critically modified condition, whereas the Klaserie and Steelpoort were in fair condition and the Blyde was in good condition. The Selati appeared to have a significant negative impact on the water quality, macroinvertebrates and fish of the Olifants River within the Kruger National Park.