Studies on the cell wall of dinoflagellate resting cysts : morphological development, ultrastructure, and chemical composition

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biology, 1994.Includes bibliographical references.by John Peter Kokinos.Ph.D

Hezbollah\u27s Operations and Networks in the United States: Two Decades in Reviews

Executive Summary ● This report aims to provide a comprehensive examination of Hezbollah-affiliated activity in America by examining all publicly-known federal criminal cases from 1997 to 2020 in the United States with a concrete link to Hezbollah. The authors found evidence of 128 individuals that meet these criteria. ● The majority of cases involve small, centralized hubs of Hezbollah operatives, who engage in illegal activities in conjunction with wider criminal enterprises to create an array of networks across America. These relationships of convenience have resulted in Hezbollah operatives collaborating with financially-motivated individuals, criminals, and other non-ideological actors, in furtherance of a broader operational mission. These arrangements, in turn, have allowed Hezbollah to profit financially and deepen its influence in the United States, even as many such cases display minimal direct connective links to the terrorist organization itself. ● Based on analysis of the cases, the authors identified two distinct categories of participation in Hezbollah-affiliated activity in America: individuals who provided financial support to Hezbollah (109 individuals), and those who provided operational support (19 individuals). ○ 87% of individuals provided financial or material support to Hezbollah as money launderers, bundlers, fraudsters, and goods smugglers, with many raising funds from others to be provided to Hezbollah or directly providing funds to the group themselves. This finding supports existing assessments that Hezbollah’s primary aspirations in the United States are to use it as a financial support hub. ○ 13% of individuals in the dataset engaged in operational conduct in support of Hezbollah, including as human smugglers, weapons procurers, pre-operational surveillance, and travelers who sought to join the group. Despite the prominence of Hezbollah’s financing activities in the United States, elements within Hezbollah remain intent on developing the capacity and capability to plot attacks on U.S. soil. ● The vast majority (92%) of cases involved network activities between two or more individuals. Larger geographic hubs operated out of Michigan (55 cases), California (19 cases), North Carolina (16 cases), and New York (15 cases). 90% of individuals operating in these four states and 76% of all cases in this dataset were a part of just six networks. ○ Large parts of network activity involved individuals with limited evidence to suggest a direct link to Hezbollah. As discussed above, these individuals actively collaborated with persons with an evidenced connection to the terrorist organization, and in many cases appear to be driven primarily by financial rather than ideological motivations. This in and of itself is a manifestation of Hezbollah’s activities in the United States, which sought to use local criminal actors in furtherance of their illegal activities. Further, in several significant instances, network activity often involved friends or family members engaged in organized conspiracies. ● 84% of individuals were convicted and sentenced to an average of 49.6 months in prison. Notably, only 19 of the 128 individuals (14%) were charged with providing material support to Hezbollah, while the others were charged with non-terrorism related offenses. Individuals sentenced on terrorism material support charges received an average sentence length of 85.6 months, almost twice as long as the average sentence for individuals not sentenced on material support charges. ● Hezbollah-affiliated individuals were primarily male (83%) and tended to be older (average age: 37) than members of other designated foreign terrorist organizations in the US, in particular the Islamic State (average age: 28)

Variants of the serotonin transporter gene and NEO-PI-R Neuroticism: No association in the BLSA and SardiNIA samples

The polymorphism in the serotonin transporter gene promoter region (5-HTTLPR) is by far the most studied variant hypothesized to influence Neuroticism-related personality traits. The results of previous studies have been mixed and appear moderated by the personality questionnaire used. Studies that used the TCI to assess Harm Avoidance or the EPQ to assess Neuroticism have found no association with the 5-HTTLPR. However, studies that used the NEO-PI-R or related instruments (NEO-PI, NEO-FFI) to measure Neuroticism have found some evidence of association. This study examines the association of variants in the serotonin transporter gene in a sample from a genetically isolated population within Sardinia (Italy) that is several times larger than previous samples that used the NEO-PI-R (N = 3,913). The association was also tested in a sample (N = 548) from the Baltimore Longitudinal Study of Aging (BLSA), in which repeated NEO-PI-R assessments were obtained. In the SardiNIA sample, we found no significant association of the 5-HTTLPR genotypes with Neuroticism or its facets (Anxiety, Angry-Hostility, Depression, Self-Consciousness, Impulsiveness, and Vulnerability). In the BLSA sample, we found lower scores on Neuroticism traits for the heterozygous group, which is inconsistent with previous studies. We also examined eight SNPs in the SardiNIA (N = 3,972) and nine SNPs in the BLSA (N = 1,182) that map within or near the serotonin transporter gene (SLC6A4), and found no association. Along with other large studies that used different phenotypic measures and found no association, this study substantially increases the evidence against a link between 5-HTT variants and Neuroticism-related traits. © 2009 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/64573/1/30932_ftp.pd

Towards an ecological understanding of dinoflagellate cyst functions

The life cycle of many dinoflagellates includes at least one nonflagellated benthic stage (cyst). In the literature, the different types of dinoflagellate cysts are mainly defined based on morphological (number and type of layers in the cell wall) and functional (long- or short-term endurance) differences. These characteristics were initially thought to clearly distinguish pellicle (thin-walled) cysts from resting (double-walled) dinoflagellate cysts. The former were considered short-term (temporal) and the latter long-term (resting) cysts. However, during the last two decades further knowledge has highlighted the great intricacy of dinoflagellate life histories, the ecological significance of cyst stages, and the need to clarify the functional and morphological complexities of the different cyst types. Here we review and, when necessary, redefine the concepts of resting and pellicle cysts, examining both their structural and their functional characteristics in the context of the life cycle strategies of several dinoflagellate species.Versión del editor

Sexual reproduction and two different encystment strategies of Lingulodinium polyedrum (Dinophyceae) in culture

Unreported aspects in the sexual cycle of the marine dinoflagellate Lingulodinium polyedrum (Stein) Dodge were described. Our observations included the description of two types of hypnozygote formation, because culture planozygotes were observed to encyst in two different ways: an ecdysal sexual stage or a spiny resting cyst. Phosphate deficiency was the main nutritional condition required for fusing gamete pairs to form resting cysts, whereas replete conditions prevented their appearance and favored the formation of ecdysal sexual forms. Mating experiments revealed the existence of two sexual types (+/−), which were enough to explain resting cyst appearance (simple heterothallism). Morphological aspects and timing of gamete mating, fusion, and the efficiency of encystment under different external levels of nitrate and phosphate were analyzed after isolating and monitoring individual pairs of fusing gametes. The staining of sexual stages showed that nuclear fusion was completed at the same time as the cytoplasmic fusion. After 1 to 2 h, the planozygotes presented one quadrolobulated nucleus. Germination of ecdysal sexual stages occurred after <24–72 h, whereas excystment of resting cysts was dependent on the studied parental cross and took place after 2–4 months. Newly germinated cells from both types of cysts had a similar, big, U-shaped nucleus. Twenty-four to 48 h after excystment, the germlings divided by desmoschisis, a process before which enlargement of the nucleus was observed.Postprin

The life history of the toxic marine dinoflagellate Protoceratium reticulatum (Gonyaulacales) in culture

Asexual and sexual life cycle events were studied in cultures of the toxic marine dinoflagellate Protoceratium reticulatum. Asexual division by desmoschisis was characterized morphologically and changes in DNA content were analyzed by flow cytometry. The results indicated that haploid cells with a C DNA content occurred only during the light period whereas a shift from a C to a 2C DNA content (indicative of S phase) took place only during darkness. The sexual life cycle was documented by examining the mating type as well as the morphology of the sexual stages and nuclei. Gamete fusion resulted in a planozygote with two longitudinal flagella, but longitudinally biflagellated cells arising from planozygote division were also observed, so one of the daughter cells retained two longitudinal flagella while the other daughter cell lacked them. Presumed planozygotes (identified by their longitudinally biflagellated form) followed two life-cycle routes: division and encystment (resting cyst formation). Both the division of longitudinally biflagellated cells and resting cyst formation are morphologically described herein. Resting cyst formation through sexual reproduction was observed in 6.1% of crosses and followed a complex heterothallic pattern. Clonal strains underwent sexuality (homothallism for planozygote formation and division) but without the production of resting cysts. Ornamental processes of resting cysts formed from the cyst wall under an outer balloon-shaped membrane and were fully developed in <1 h. Obligatory dormancy period was of ∼4 months. Excystment resulted in a large, rounded, pigmented, longitudinally biflagellated but motionless, thecate germling that divided by desmoschisis. Like the planozygote, the first division of the germling yielded one longitudinally biflagellated daughter cell and another without longitudinal flagella. The longitudinal biflagellation state of both sexual stages and of the first division products of these cells is discussed.Postprin