The life cycles of cryptogams

Meiosis and karyogamy are recognized as control points in the life cycle of cryptogams. The control of meiosis is evidently complex and in yeast, and by analogy in all cryptogams, involves progressive gene activation. The causes of the delay in meiosis in diplohaplontic and diplontic organisms, and the manner in which the block is removed remain to be discovered. There is accumulating evidence that cytoplasmic RNA plays an important role in meiotic division.Many features of gametogenesis are still obscure. The tendency to oogamy has provided the opportunity for the laying down of long-lived messenger RNA in the abundant cytoplasm of the female gamete. The sporophytic nature of the developing zygote can in this way be partially pre-determined. There is evidence that this is the situation in the ferns.Specific molecules (probably arabino-galacto-proteins) on the surface of the plasma membrane are likely to account both for gametic selection, and the readiness with which appropriate gametes fuse. The dikaryotic condition indicates that nuclear fusion is not inevitable following plasmogamy. The ultimate fusion of the nuclei may result from quite simple changes in the nuclear surface. Exposure of lipid, for example, would lead to fusion as a result of hydrophobic forces.Aberrations of cryptogamic life cycles are numerous. The nuclear relationships of many aberrant cycles are unknown. In general it appears that the maintenance of sporophytic growth depends upon the presence of at least two sets of chromosomes. Conversely the maintenance of gametophytic growth in cultures obtained aposporously appears to be impossible in the presence of four sets of chromosomes, or more. These results raise important problems of the effect of gene dosage on development.La meiosis y la cariogamia son reconocidas como puntos de control en los ciclos de vida de las criptógamas. El control de la meiosis es evidentemente complejo y en levaduras, y por analogía en todas las criptógamas, incluye la activación progresiva del gen. Las causas de este retraso en la meiosis de los organismos diplohaplónticos y diplónticos y la manera en que se elimina el bloqueo aun se desconoce. Existe una acumulación de evidencias que indican que el RNA citoplásmico juega un importante papel en la división meiótica.Muchas características de la gametogénesis están aún oscuras. La tendencia hacia la oogamia ha permitido la oportunidad de establecer la longevidad del ARN mensajero en el abundante citoplasma del gameto femenino. La naturaleza del esporófito desarrollada a partir del cigoto puede ser, en este sentido, parcialmente predeterminada. Hay evidencias que esta es la situación en los helechos.La selección gamética y la prontitud con que se fusionan los gametos apropiados, probablemente se deba a moléculas específicas (quizás arabino-galacto-proteínas) de la superficie de la membrana plasmática. La condición dicariótica indica que la fusión nuclear no es inevitable como consecuencia de la plasmogamia. La fusión definitiva de los núcleos puede resultar de unos cambios bastante simples en la superfice nuclear. La exposición de lípidos, por ejemplo, conduciría a la fusión como resultado de fuerzas hidrofóbicas.Las aberraciones en el ciclo de vida de las criptógamas son numerosas. Las relaciones nucleares de muchos de los ciclos aberrantes son desconocidas. En general parece que el mantenimiento del crecimiento esporofítico depende de la presencia, por lo menos, de dos juegos de cromosomas. De manera contraria, el mantenimiento del crecimiento del gametófito en cultivos obtenidos apospóricamente parece ser imposible en presencia de cuatro juegos de cromosomas o más. Estos resultados aumentan la importancia de los problemas de la dosificación del gen en el desarrollo

Barnes Hospital Bulletin

https://digitalcommons.wustl.edu/bjc_barnes_bulletin/1078/thumbnail.jp

Journalistic freedom and the surveillance of journalists post-Snowden

A paradigmatic shift is sometimes revealed by an unanticipated and extraordinary event, and so it was with Edward Snowden in 2013. A National Security Agency (NSA) contractor, Snowden was so appalled at the exponential expansion of covert digital surveillance that he decided it was his moral duty to inform the public, indeed the world. This he did from a hotel room in Hong Kong when he gave a small group of selected journalists access to 1.7 million classified documents taken from the NSA. These documents revealed the global snooping capabilities of the NSA and its ‘Five Eyes’ intelligence agency partners (ASIO in Australia, CSE in Canada, GCSB in New Zealand, and the GCHQ in United Kingdom). The Five Eyes can vacuum up just about all digital communications anywhere, anytime, and much else besides if they are so minded. Many who take a deep interest in signals intelligence thought these Anglo-Saxon agencies had probably increased their capabilities since 9/11, but even they were shocked when Snowden revealed the sheer scale – it far exceeded any estimate of capability

Effects of Alternaria alternata f.sp. lycopersici toxins on pollen

Effects of the phytotoxic compounds (AAL-toxins) isolated from cell-free culture filtrates of Alternaria alternata f.sp. lycopersici on in vitro pollen development were studied. AAL-toxins inhibited both germination and tube growth of pollen from several Lycopersicon genotypes. Pollen from susceptible genotypes, however, was more sensitive for AAL-toxins than pollen from resistant plants, while pollen of species not belonging to the host range of the fungus was not significantly affected by the tested toxin concentrations. AAL-toxins elicit symptoms in detached leaf bioassays indistinguishable from those observed on leaves of fungal infected tomato plants, and toxins play a major role in the pathogenesis. Apparently, pathogenesis-related processes and mechanisms involved in disease resistance are expressed in both vegetative and generative tissues. This overlap in gene expression between the sporophytic and gametophytic level of a plant may be advantageously utilized in plant breeding programmes. Pollen may be used to distinguish susceptible and resistant plants and to select for resistances and tolerances against phytotoxins and other selective agents.

Modulation of swimming in the gastropod Melibe leonina by nitric oxide

Nitric oxide (NO) is a gaseous intercellular messenger produced by the enzyme nitric oxide synthase. It has been implicated as a neuromodulator in several groups of animals, including gastropods, crustaceans and mammals. In this study, we investigated the effects of NO on the swim motor program produced by isolated brains and by semi-intact preparations of the nudibranch Melibe leonina. The NO donors sodium nitroprusside (SNP, 1 mmol l–1) and S-nitroso-N-acetylpenicillamine (SNAP, 1 mmol l–1) both had a marked effect on the swim motor program expressed in isolated brains, causing an increase in the period of the swim cycle and a more erratic swim rhythm. In semi-intact preparations, the effect of NO donors was manifested as a significant decrease in the rate of actual swimming. An NO scavenger, reduced oxyhemoglobin, eliminated the effects of NO donors on isolated brains, supporting the assumption that the changes in swimming induced by donors were actually due to NO. The cGMP analogue 8-bromoguanosine 3′,5′-cyclic monophosphate (1 mmol l–1) produced effects that mimicked those of NO donors, suggesting that NO is working via a cGMP-dependent mechanism. These results, in combination with previous histological studies indicating the endogenous presence of nitric oxide synthase, suggest that NO is used in the central nervous system of Melibe leonina to modulate swimming

Sony, Cyber Security, and Free Speech: Preserving the First Amendment in the Modern World

Reprinted from 16 U.C. Davis Bus. L.J. 309 (2016). This paper explores the Sony hack in 2014 allegedly launched by the North Korean government in retaliation over Sony’s production of The Interview and considers the hack’s chilling impact on speech in technology. One of the most devastating cyber attacks in history, the hack exposed approximately thirty- eight million files of sensitive data, including over 170,000 employee emails, thousands of employee social security numbers and unreleased footage of upcoming movies. The hack caused Sony to censor the film and prompted members of the entertainment industry at large to tailor their communication and conform storylines to societal standards. Such censorship cuts the First Amendment at its core and exemplifies the danger cyber terror poses to freedom of speech by compromising Americans’ privacy in digital mediums. This paper critiques the current methods for combatting cyber terror, which consist of unwieldy federal criminal laws and controversial information sharing policies, while proposing more promising solutions that unleash the competitive power of the free market with limited government regulation. It also recommends legal, affordable and user-friendly tools anyone can use to secure their technology, recapture their privacy and exercise their freedom of speech online without fear of surreptitious surveillance or retaliatory exposure

Medical Literary Messenger (Vol. 3, No. 2, Spring/Summer 2016)

Exposure / Dan Campion -- The Second Floor Shop B / Hil Scott -- Incubator Memory / Meridian Johnson -- Take Me to Richmond / Derick Nelson Jenkins -- Destination Unknown / Derick Nelson Jenkins -- Symmetry / Derick Nelson Jenkins -- The Aide / Erika D. Price -- Subconscious / David Yoffe -- What My Uncle is Thinking / Tamsyn Brennan -- Progression / E. F. Schraeder -- Waiting / Justin Nicholes -- Only 1,482 Steps From the Massey Cancer Center Entrance / Dodge Havens -- At Hardy-Owen Funeral Home, Conveniently Located on Dixie Highway / Monique Kluczykowski -- After the Diagnosis / Chelsea Krieg -- A Journey of a Thousand Steps / Leslie Bobb -- Average Worries / John Davis Jr -- Cadavers / Cheyenne Marco -- Ribosome and Friends / Hil Scott -- Matrix B / Hil Scott -- Chicago Portrait no. 37: Herpes in the Botanical Garden / Erika D. Price -- Dhyanam (Meditation) / Priyadarshini Komala -- Miscarriage / Sarah Gane Burton -- Intern Year / Megan Coe -- Waiting Room (Pulse) / Stephen C. Middleton -- Steady My Heart / Emily Lasinsky -- Into the ER, We Rush / Susan April -- Flow / Derick Nelson Jenkins

Kanamycin resistance during in vitro development of pollen from transgenic tomato plants

Effects of kanamycin on pollen germination and tube growth of pollen from non-transformed plants and from transgenic tomato plants containing a chimaeric kanamycin resistance gene were determined. Germination of pollen was not affected by the addition of kanamycin to the medium in both genotypes. Kanamycin, however, severely affected tube growth of pollen from non-transformed plants, while pollen from plants containing the chimaeric gene were less sensitive and produced significantly longer tubes at kanamycin concentrations between 200-400 mg l-1. Apparently, this resistance for kanamycin correlates with the expression of the chimaeric gene during male gametophytic development.

A biogenic amine and a neuropeptide act identically: tyramine signals through calcium in drosophila tubule stellate cells

Insect osmoregulation is subject to highly sophisticated endocrine control. In Drosophila, both Drosophila kinin and tyramine act on the Malpighian (renal) tubule stellate cell to activate chloride shunt conductance, and so increase the fluid production rate. Drosophila kinin is known to act through intracellular calcium, but the mode of action of tyramine is not known. Here, we used a transgenically encoded GFP::apoaequorin translational fusion, targeted to either principal or stellate cells under GAL4/UAS control, to demonstrate that tyramine indeed acts to raise calcium in stellate, but not principal cells. Furthermore, the EC(50) tyramine concentration for half-maximal activation of the intracellular calcium signal is the same as that calculated from previously published data on tyramine-induced increase in chloride flux. In addition, tyramine signalling to calcium is markedly reduced in mutants of NorpA (a phospholipase C) and itpr, the inositol trisphosphate receptor gene, which we have previously shown to be necessary for Drosophila kinin signalling. Therefore, tyramine and Drosophila kinin signals converge on phospholipase C, and thence on intracellular calcium; and both act to increase chloride shunt conductance by signalling through itpr. To test this model, we co-applied tyramine and Drosophila kinin, and showed that the calcium signals were neither additive nor synergistic. The two signalling pathways thus represent parallel, independent mechanisms for distinct tissues (nervous and epithelial) to control the same aspect of renal function