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Topic Review
The Role of Commensal and other Non-Pathogenic Bacteria
Not only pathogenic bacteria are reservoirs of antibiotic resistance and virulence genes. Opportunistic pathogenic bacteria, commensal bacteria, and mutualistic bacteria (here named non-pathogenic for simplification) may also carry resistance and virulence genes. However, contrary to pathogenic strains, which are the target of the immune system, non-pathogenic bacteria can colonize hosts for prolonged periods because hosts do not need to be rid of them. Thus, the basic reproductive number of a non-pathogenic bacterial strain, a measure of the strain’s fitness and denoted as R0, is likely to be much higher than one. That is, the expected number of colonized hosts by a single colonized host in a population not yet colonized by that strain is higher than one, which implies that this strain can spread exponentially among hosts. This spread has peculiar consequences for the spread of virulence and resistance genes. For example, computer models that simulate the spread of these genes have shown that their diversities should correlate positively throughout microbiomes. Bioinformatics analysis with real data corroborates this expectation.
  • 760
  • 07 Feb 2023
Topic Review
Self-Incompatibility in Orchids
Self-incompatibility (SI) refers to the inability of hermaphroditic angiosperms to self-pollinate, which promotes outcrossing or hybridization. 
  • 759
  • 13 Dec 2021
Topic Review
Microchromosome Organization in Birds
Interchromosomal rearrangements involving microchromosomes are rare events in birds. To date, they have been found mostly in Neognathae and Neoaves (e.g., Psittaciformes, Falconiformes, and Cuculiformes), although only a few orders have been analyzed. Hence, cytogenomic studies focusing on microchromosomes in species belonging to different bird orders are essential to shed more light on the avian chromosome and karyotype evolution. Relevant hypothetical Neognathae, Neoaves and other ancestral karyotypes can be reconstructed to trace these rearrangements. In a more recent study, a comparative chromosome mapping for chicken microchromosomes 10 to 28 was performed using interspecies BAC-based FISH hybridization in five species, representing four Neoaves orders (Caprimulgiformes, Piciformes, Suliformes, and Trogoniformes). These results suggest that the ancestral microchromosomal syntenies are conserved in Pteroglossus inscriptus (Piciformes), Ramphastos tucanus tucanus (Piciformes), and Trogon surrucura surrucura (Trogoniformes). On the other hand, chromosome reorganization in Phalacrocorax brasilianus (Suliformes) and Hydropsalis torquata (Caprimulgiformes) included fusions involving both macro- and microchromosomes. Fissions in macrochromosomes were observed in P. brasilianus and H. torquata. No interchromosomal rearrangement involving microchromosomes were found to be shared between avian orders where rearrangements were detected. These findings suggest that convergent evolution involving microchromosomal change is a rare event in birds and may be appropriate in cytotaxonomic inferences in orders where these rearrangements occurred.
  • 750
  • 21 Oct 2022
Topic Review
Molluscivorous and Vermivorous Conus Species
It is generally believed that more than 700 Conus species have evolved during the last 50 million years. With the highest species abundance occurring in southeast Asia, most Conus can be found in the shallow waters of tropical and subtropical oceans. Conus is widely distributed in rocky shores, sandy beaches, coral reefs and intertidal waters, with depths reaching up to over 600 m. Nowadays, Conus species are generally overexploited, and some species are now endangered. Exploring these waters of potentially high species diversity could enrich our understanding of their population’s genetic structure and provide the missing pieces for clarifying Conus evolution. As the conotoxin compounds vary greatly throughout the growth stages and across geolocations within the same species, further investigation of these species-specific regional distribution differences may provide crucial insights for artificial breeding and harvesting specific bioactive compounds in the future.
  • 736
  • 18 Feb 2022
Topic Review
Invasion of African Clarias gariepinus in Bangladesh
The African catfish Clarias gariepinus has been introduced for aquaculture in Bangladesh due to the scarcity of indigenous C. batrachus fingerlings. The African catfish Clarias gariepinus is a highly carnivorous species and predates small indigenous freshwater fishes when escaping into natural water bodies. However, the government of Bangladesh has banned the farming of C. gariepinus due to the carnivorous nature of this species. The introduction of C. gariepinus caused native biodiversity loss due to its predatory nature.
  • 670
  • 25 Feb 2022
Topic Review
Photosynthesis and Rubisco: An Evolutionary Perspective
When oxygenic photosynthesis evolved around 2.4 billion years ago, it is believed that all the oxygen-evolving organisms used the ribulose bisphosphate carboxylase-oxygenase (Rubisco)- photosynthetic carbon reduction cycle (PCRC) despite there being five other major CO2 assimilation pathways. Rubisco-PCRC was dominant, with the highest specific activity in presence of carbon dioxide at high concentrations without the presence of oxygen. 
  • 617
  • 13 Apr 2022
Topic Review
Relationship between Latent-Toxoplasmosis and Depression
Latent infection of the globally spread parasite Toxoplasma gondii in humans has been associated with changes in personality and behavior. Numerous studies have investigated the effect of toxoplasmosis on depression, but their results are inconsistent. Our study focused on the effect of latent toxoplasmosis on depression in men and women in association with their fertility. In 2016–2018, we recruited clients (677 men and 664 women) of the Center for Assisted Reproduction and asked them to complete a standardized Beck Depression Inventory-II. In women without fertility problems, we found higher depression scores in Toxoplasma-positive than in Toxoplasma-negative (p = 0.010, Cohen’s d = 0.48). Toxoplasma-positive infertile men, on the other hand, had lower depression scores than Toxoplasma-negative infertile men (p ≤ 0.001, Cohen’s d = 0.48). Our results are consistent with the previously described effects of latent toxoplasmosis, which seem to go in opposite directions regarding the effect on personality and behavior of men and women. Our results could be explained by gender-contrasting reactions to chronic stress associated with lifelong infection. This suggests that due to gender differences in the impact of latent toxoplasmosis, future studies ought to perform separate analyses for women and men. 
  • 601
  • 26 Aug 2021
Topic Review
Layered Model of Evolution of Cellular Functionalities
As a phenomenon, cancer is a disease related to multicellular evolution, i.e., cancer in general is understood to be a failure of the multicellular systems and is considered a reversal to unicellularity. Cancer cells are like unicellular organisms that benefit from ancestral-like traits. As a disease, cancer can be interpreted as (a) a destruction of cooperative behaviors underlying multicellular evolution, (b) a disruption of molecular networks established during the emergence of multicellularity or (c) an atavistic state resulting from reactivation of primitive programs typical of the earliest unicellular species. From this point of view and in accordance with the layered model of evolution of cellular functionalities, cancer transformation can occur as a result of huge disturbances or the destruction of functionalities that are located in the multicellular layer.
  • 599
  • 20 Apr 2022
Topic Review
Virtual Anthropology and Paleoneurology
Advances in neuroscience have made it possible to obtain increasing information on the anatomy of the brain, at ever-higher resolutions, with different imaging techniques, on ever-larger samples. At the same time, paleoanthropology has to deal with partial reflections on the shape of the brain, on fragmentary specimens and small samples in an attempt to approach the morphology of the brain of past human species. Paleoanthropology has much to gain from interacting more with the field of neuroimaging. Improving our understanding of the morphology of the endocast necessarily involves studying the external surface of the brain and the link it maintains with the internal surface of the skull. The contribution of neuroimaging will allow us to better define the relationship between brain and endocast. Models of intra- and inter-species variability in brain morphology inferred from large neuroimaging databases will help make the most of the rare endocasts of extinct species. Moreover, exchanges between these two disciplines will also be beneficial to our knowledge of the Homo sapiens brain. Documenting the anatomy among other human species and including the variation over time within our own species are approaches that offer us a new perspective through which to appreciate what really characterizes the brain of humanity today. 
  • 597
  • 09 Nov 2021
Topic Review
Distinguishing Evolutionary Conservation from Derivedness
While the concept of “evolutionary conservation” has enabled biologists to explain many ancestral features and traits, it has also frequently been misused to evaluate the degree of changes from a common ancestor, or “derivedness”. From a methodological aspect, “conservation” mainly considers genes or traits which species have in common, while “derivedness” additionally covers those that are not commonly shared, such as novel or lost traits and genes to evaluate changes from the time of divergence from a common ancestor. Due to these differences, while conservation-oriented methods are effective in identifying ancestral features, they may be prone to underestimating the overall changes accumulated during the evolution of certain lineages.
  • 547
  • 06 Apr 2022
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