Molecular Analysis of the Gal/GalNAc Adhesin of Entamoeba histolytica1

Attachment of Entamoeba histolytica to colonic epithelium and a variety of other target cells is mediated by a galactosc/N-acetyl D-galactosamine (Gal/GalNAc) inhibitable adhesin. Seven monoclonal antibodies specific for nonoverlapping epitopes of the 170 kDa subunit have been shown to have distinct effects on adherence. Four of these monoclonal antibodies inhibit or have no effect on amebic adherence while two others enhance amebic adherence. The epitopes recognized by these seven monoclonal antibodies have been mapped to the extracellular cysteine rich region of the 170 kDa subunit. The conformational nature of the epitopes was examined by testing monoclonal antibody reactivity with isolated regions of the 170 kDa subunit expressed as fusion proteins in E. coli and also with denatured native adhesin. These analyses suggested that three of monoclonal antibodies recognized conformational epitopes while the remaining four recognized linear epitopes. The mapping of these monoclonal antibodies have identified functionally important regions of the Gal/GalNAc adhesin and have also shown that recombinant Gal/GalNAc adhesin, when expressed in E. coli, retained at least some of its native conformation.     

Locomotor response to predator threat in red colobus monkeys

The locomotor patterns of red colobus monkeys (Colobus badius) were scored under three different conditions: normal daily activities, in sight of a terrestrial predator, and after the playback of a crowned hawk-eagle call. Relative to the normal movement activities, the terrestrial and avian predator experiments showed fleeing movements to be very rapid with an increase in the frequency of leaping and vertical bounding. Movement distances also increased in response to the avian playback experiments. Although rare, it is possible that rapid movements may better reflect anatomical design than movements during normal daily activities.     

Insect-transmitted vertebrate viruses: Flaviviridae

Summary The Flaviviridae include almost 70 viruses, nearly half of which have been associated with human disease. These viruses are among the most important arthropod-borne viruses worldwide and include dengue, yellow fever, and Japanese encephalitis viruses. Morbidity and mortality caused by these viruses vary, but collectively they account for millions of encephalitis, hemorrhagic fever, arthralgia, rash, and fever cases per year. Most of the members of this family are transmitted between vertebrate hosts by arthropod vectors, most commonly mosquitoes or ticks. Transmission cycles can be simple or complex depending on the hosts, vectors, the virus, and the environmental factors affecting both hosts and viruses. Replication of virus in invertebrate hosts does not seem to result in any significant pathology, which suggests a close evolutionary relationship between virus and vector. Another example of this relationship is the ability of these viruses to grow in invertebrate cell culture, where replication usually results in a steady state, persistent infection, often without cytopathic effect. Yields of virus from insect cell culture vary but are generally similar to yields in vertebrate cells. Replication kinetics are comparable between insect and vertebrate cell lines, despite differences in incubation temperature. Both vertebrate and insect cell culture systems continue to play a significant role in flavivirus isolation and the diagnosis of disease caused by these agents. Additionally, these culture systems permit the study of flavivirus attachment, penetration, replication, and release from cells and have been instrumental in the production and characterization of live-attenuated vaccines. Both vertebrate and insect cell culture systems will continue to play a significant role in basic and applied flavivirus research in the future.     

Phenology and thallus size in a non-native population of Gracilaria vermiculophylla

Phenology, or seasonal variation in life cycle events, is poorly described for many macroalgal species. We describe the phenology of a non-native population of Gracilaria vermiculophylla whose thalli are free-living or anchored by decorating polychaetes to tube caps. At a site in South Carolina, USA, we sampled 100 thalli approximately every month from January 2014 to January 2015. We assessed the reproductive state and measured thallus size based on wet weight, thallus length, and thallus surface area from herbarium mounts. Because life cycle stage cannot be assigned using morphology, we implemented a PCR assay to determine the life cycle stage—tetrasporophyte, female gametophyte, or male gametophyte—of each thallus. Tetrasporophytes dominated throughout the year, making up 81%–100% of thalli sampled per month. Reproductive tetrasporophytes varied between 0% and 65% of monthly samples and were most common in warm summer months (July through September) when thalli also tended to be larger. The vast majority of the reproductive thalli were worm-anchored and not fixed to hard substratum via a holdfast. Thus, free-living thalli can be reproductive and potentially seed new non-native populations. Given G. vermiculophylla reproduction seems tied closely to temperature, our work suggests phenology may change with climate-related changes in seawater temperatures. We also highlight the importance of understanding the natural history of macroalgae to better understand the consequence of range expansions on population dynamics.     

Nocturnal primates of kibale forest: Effects of selective logging on prosimian densities

To evaluate the potential impact of logging on nocturnal primates, densities ofGalago demidovii, G. inustus, andPerodictus potto were determined in two areas of the Kibale Forest Reserve, Uganda. One of these areas had been logged at a moderate level in the late 1960's, while the second area was relatively undisturbed. The density of the nocturnal primates was lower in the logged area than in the neighboring unlogged area. For the most frequently sighted nocturnal primate,G. demidovii, sightings were spatially clustered both within a year and between years, suggesting that clumped resources and/or social factors were influencing space use.     

The initial age-associated decline in early T-cell progenitors reflects fewer pre-thymic progenitors and altered signals in the bone marrow and thymus microenvironments

Age-related thymus involution results in decreased T-cell production, contributing to increased susceptibility to pathogens and reduced vaccine responsiveness. Elucidating mechanisms underlying thymus involution will inform strategies to restore thymopoiesis with age. The thymus is colonized by circulating bone marrow (BM)-derived thymus seeding progenitors (TSPs) that differentiate into early T-cell progenitors (ETPs). We find that ETP cellularity declines as early as 3 months (3MO) of age in mice. This initial ETP reduction could reflect changes in thymic stromal niches and/or pre-thymic progenitors. Using a multicongenic progenitor transfer approach, we demonstrate that the number of functional TSP/ETP niches does not diminish with age. Instead, the number of pre-thymic lymphoid progenitors in the BM and blood is substantially reduced by 3MO, although their intrinsic ability to seed and differentiate in the thymus is maintained. Additionally, Notch signaling in BM lymphoid progenitors and in ETPs diminishes by 3MO, suggesting reduced niche quality in the BM and thymus contribute to the early decline in ETPs. Together, these findings indicate that diminished BM lymphopoiesis and thymic stromal support contribute to an initial reduction in ETPs in young adulthood, setting the stage for progressive age-associated thymus involution.     

Prognostic biomarkers for survival in mucosal melanoma

Mucosal melanoma (MM) is a rare subtype of melanoma with an aggressive clinical course. In cutaneous melanoma (CM), the absence of pigmentation and presence of NRAS/KRAS mutations are biomarkers indicating an aggressive clinical course with shorter overall survival. Similar data for MM are missing. We present the real-world outcome data in a cohort of genotyped MM patients and assessed the prognostic relevance of pigmentation- and NRAS/KRAS mutation status. We correlated pathological reports and clinical data with overall survival of patients with MM. Furthermore, we performed clinically integrated molecular genotyping and analyzed real world treatment regimens for covariates associated with clinical outcome. We identified 39 patients with available clinical and molecular data. Patients with amelanotic MM had a significantly shorter overall survival (p = .003). In addition, the presence of a NRAS or KRAS mutation was significantly associated with poor overall survival (NRAS or KRAS p = .024). Currently, it is unknown if the same prognostic relevance for the lack of pigmentation and RAS mutations in CM, exists in MM. Here we analyzed a cohort of MM for outcome measures and determined that two known prognostic biomarkers for CM are in fact novel prognosticators for MM.     

Neural lineage differentiation of human pluripotent stem cells: Advances in disease modeling

Brain diseases affect 1 in 6 people worldwide. These diseases range from acute neurological conditions such as stroke to chronic neurodegenerative disorders such as Alzheimer’s disease. Recent advancements in tissue-engineered brain disease models have overcome many of the different shortcomings associated with the various animal models, tissue culture models, and epidemiologic patient data that are commonly used to study brain disease. One innovative method by which to model human neurological disease is via the directed differentiation of human pluripotent stem cells (hPSCs) to neural lineages including neurons, astrocytes, and oligodendrocytes. Three-dimensional models such as brain organoids have also been derived from hPSCs, offering more physiological relevance due to their incorporation of various cell types. As such, brain organoids can better model the pathophysiology of neural diseases observed in patients. In this review, we will emphasize recent developments in hPSC-based tissue culture models of neurological disorders and how they are being used to create neural disease models.     

Synthesis of prostaglandin E2 and prostaglandin F2α by toadfish red blood cells

Saline washed red blood cells of the toadfish convert [1-¹⁴C] arachidonic acid to products that cochromatograph with prostaglandin E₂ and prostaglandin F_2α. This synthesis is inhibited by indomethacin (10 μg/ml). Conversion of arachidonic acid to prostaglandin E₂ was confirmed by mass spectrometry. When saline washed toadfish red blood cells were incubated with a mixture of [1-¹⁴C]-arachidonic acid and [5,6,8,9,11,12,14,15,-³H]-arachidonic acid, comparison of the isotope ratios of the radioactive products indicated that prostaglandin F_2α was produced by reduction of prostaglandin E₂. The capacity of toadfish red blood cells to reduce prostaglandin E₂ to prostaglandin F_2α was confirmed by incubation of the cells with [1-¹⁴C] prostaglandin E₂.     

Trichothecene production by Fusarium species isolated from grain and pasture throughout New Zealand

Liquid cultures of 200 Fusarium isolates selected to represent the most common species found in autumn pasture (70 isolates) and in grain (130 isolates) grown in New Zealand were analysed for trichothecenes and related compounds. Production of butenolide, cyclonerodiol derivatives and culmorins was also measured. The principal trichothecenes produced were derivatives of either nivalenol (NIV), deoxynivalenol (DON) or scirpentriol (Sctol), in order of frequency. The principal trichothecene producing species were F. crookwellense, F. culmorum and F. graminearum. Isolates of the first two species were predominantly NIV-chemotypes with one or two isolates respectively as Sctol-chemotypes. F. graminearum showed equal quantities of NIV- and DON-chemotypes, with the DON-chemotypes producing primarily 15-acetyldeoxynivalenol (15-ADON).