Genetic relatedness of Plasmodium falciparum isolates and the origin of allelic diversity at the merozoite surface protein-1 (MSP-1) locus in Brazil and Vietnam

BACKGROUND: Despite the extensive polymorphism at the merozoite surface protein-1 (MSP-1) locus of Plasmodium falciparum, that encodes a major repetitive malaria vaccine candidate antigen, identical and nearly identical alleles frequently occur in sympatric parasites. Here we used microsatellite haplotyping to estimate the genetic distance between isolates carrying identical and nearly identical MSP-1 alleles. METHODS: We analyzed 28 isolates from hypoendemic areas in north-western Brazil, collected between 1985 and 1998, and 23 isolates obtained in mesoendemic southern Vietnam in 1996. MSP-1 alleles were characterized by combining PCR typing with allele-specific primers and partial DNA sequencing. The following single-copy microsatellite markers were typed : Polyα, TA42 (only for Brazilian samples), TA81, TA1, TA87, TA109 (only for Brazilian samples), 2490, ARAII, PfG377, PfPK2, and TA60. RESULTS: The low pair-wise average genetic distance between microsatellite haplotypes of isolates sharing identical MSP-1 alleles indicates that epidemic propagation of discrete parasite clones originated most identical MSP-1 alleles in parasite populations from Brazil and Vietnam. At least one epidemic clone propagating in Brazil remained relatively unchanged over more than one decade. Moreover, we found no evidence that rearrangements of MSP-1 repeats, putatively created by mitotic recombination events, generated new alleles within clonal lineages of parasites in either country. CONCLUSION: Identical MSP-1 alleles originated from co-ancestry in both populations, whereas nearly identical MSP-1 alleles have probably appeared independently in unrelated parasite lineages

Population bottlenecks constrain host microbiome diversity and genetic variation impeding fitness

It is becoming increasingly clear that microbial symbionts influence key aspects of their host's fitness, and vice versa. This may fundamentally change our thinking about how microbes and hosts interact in influencing fitness and adaptation to changing environments. Here we explore how reductions in population size commonly experienced by threatened species influence microbiome diversity. Consequences of such reductions are normally interpreted in terms of a loss of genetic variation, increased inbreeding and associated inbreeding depression. However, fitness effects of population bottlenecks might also be mediated through microbiome diversity, such as through loss of functionally important microbes. Here we utilise 50 Drosophila melanogaster lines with different histories of population bottlenecks to explore these questions. The lines were phenotyped for egg-to-adult viability and their genomes sequenced to estimate genetic variation. The bacterial 16S rRNA gene was amplified in these lines to investigate microbial diversity. We found that 1) host population bottlenecks constrained microbiome richness and diversity, 2) core microbiomes of hosts with low genetic variation were constituted from subsets of microbiomes found in flies with higher genetic variation, 3) both microbiome diversity and host genetic variation contributed to host population fitness, 4) connectivity and robustness of bacterial networks was low in the inbred lines regardless of host genetic variation, 5) reduced microbial diversity was associated with weaker evolutionary responses of hosts in stressful environments, and 6) these effects were unrelated to Wolbachia density. These findings suggest that population bottlenecks reduce hologenomic variation (combined host and microbial genetic variation). Thus, while the current biodiversity crisis focuses on population sizes and genetic variation of eukaryotes, an additional focal point should be the microbial diversity carried by the eukaryotes, which in turn may influence host fitness and adaptability with consequences for the persistence of populations

Standardization Beyond Form: Ideologies, Institutions, and the Semiotics of Nepali Sign Language.

Leaders of Nepal’s deaf institutions are currently working to standardize Nepali Sign Language (NSL). Through an examination of this process, this dissertation explores the relationship between the formal and ideological aspects of language standardization. First, I argue that standardization projects need not involve writing, though they must involve the objectification of some level of linguistic form. While lacking a written form does not preclude a standardization project it can affect its formal and ideological thrusts. In the case of NSL, the fact that its unwritten status focuses standardization efforts on the level of the lexicon has limited the project’s gate-keeping potential by permitting a wide range of signing practices to count as standard. This has allowed different deaf institutions to promote grammatically distinct forms of signing that reflect and promote distinct ideologies about the nature of the language, while still adhering to the same overarching standardization project. However, I demonstrate that teachers in the schools and associations cannot fully dictate the kinds of linguistic forms their students will be exposed to and produce. This introduces additional formal and ideological variation into these institutional contexts. Finally, having demonstrated that the formal and ideological elements of any language standardization project influence one another, I note that the nature of their relationships in any given case is not inherent or fixed. Therefore, the primary argument of this dissertation is that it is necessary to attend to the ways in which language standardization projects attempt to reduce variation not only in the formal properties of language but also in the semiotic means by which linguistic form and social meaning are linked. These claims are grounded in the production and analysis of detailed transcripts, making this dissertation one of the very few efforts within linguistic anthropology to carefully record and present the formal properties of natural signed communication. In addition, the arguments I offer about language standardization contribute to the discipline’s understanding of language ideologies more broadly by highlighting the multiplicity of linguistic forms, ideological perspectives, and the semiotic processes by which linkages between the two are created and reinforced.Ph.D.AnthropologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/58405/1/eghoffma_1.pd

Mosaic structure in the spines of Holopneustes porossisimus

Sea urchin spines of Holopneustes porossisimus are porous singlecrystals, with the pores being filled with a material rich in carbon,silicon, fluorine and sodium. The magnesian calcite constituting thespine is highly strained. Even though the spines appear to be singlecrystalline on a macroscopic scale, the calcitic material exhibits anextended defect network. We find dislocations as well as rotational andother, not yet identified boundaries. We also observe within spinecalcite a patterned distribution of sulphur. Both distributions, that ofthe defect network and that of sulphur resemble in their pattern to eachother and have a similar mesh size of 50 nm. We conclude from theseobservations that they arise from the growth process of the spine andaccount for the mosaicity within the spine single crystals

Luteal and placental function in the bitch: spatio-temporal changes in prolactin receptor (PRLr) expression at dioestrus, pregnancy and normal and induced parturition

Background: Endocrine mechanisms governing canine reproductive function remain still obscure. Progesterone (P4) of luteal origin is required for maintenance of pregnancy. Corpora lutea (CL) are gonadotrop-independent during the first third of dioestrus; afterwards prolactin (PRL) is the primary luteotropic factor. Interestingly, the increasing PRL levels are accompanied by decreasing P4 concentrations, thus luteal regression/luteolysis occurs in spite of an increased availability of gonadotropic support. PRL acts through its receptor (PRLr), the expression of which has not yet been thoroughly investigated at the molecular and cellular level in the dog. Methods: The expression of PRLr was assessed in CL of non-pregnant dogs during the course of dioestrus (days 5, 15, 25, 35, 45, 65 post ovulation; p.o.) as well as in CL, the utero/placental compartments (Ut/Pl) and interplacental free polar zones (interplacental sites) from pregnant dogs during the pre-implantation, post-implantation and mid-gestation period of pregnancy and during the normal and antigestagen-induced luteolysis. Expression of PRLr was tested by Real Time PCR, immunohistochemistry and in situ hybridization. Results: In non-pregnant CL the PRLr expression was significantly upregulated at day 15 p.o. and decreased significantly afterwards, towards the end of dioestrus. CL of pregnancy showed elevated PRLr expression until mid gestation while prepartal downregulation was observed. Interestingly, placental but not interplacental expression of PRLr was strongly time-related; a significant upregulation was observed towards mid-gestation. Within the CL PRLr was localized to the luteal cells; in the Ut/Pl it was localized to the fetal trophoblast and epithelial cells of glandular chambers. Moreover, in mid-pregnant animals treated with an antigestagen, both the luteal and placental, but not the uterine PRLr were significantly downregulated. Conclusions: The data presented suggest that the luteal provision of P4 in both pregnant and non-pregnant dogs may be regulated at the PRLr level. Furthermore, a role of PRL not only in maintaining the canine CL function but also in regulating the placental function is strongly suggested. A possible functional interrelationship between luteal P4 and placental and luteal PRLr expression also with respect to the prepartal luteolysis is implied

The 2023 Whippoorwill Award: The 2023 Whippoorwill Award: Complex Representations of Rural Identities and Places

Announcing the 2023 Whippoorwill Award winners