Fluorescence Microscopy of Cells in Culture - Serious attempts at the culture of whole tissues and isolated cells were first undertaken in the early s as a technique for investigating the behavior of animal cells in an isolated and highly controlled environment. The term tissue culture arose because most of the early cells were derived from primary tissue explants, a technique that dominated the field for over 50 years.
As established cell lines emerged, the application of well-defined normal and transformed cells in biomedical investigations has become an important staple in the development of cellular and molecular biology. This fluorescence image gallery explores over 30 of the most common cell lines, labeled with a variety of fluorophores using both traditional staining methods as well as immunofluorescence techniques.
Observing Mitosis with Fluorescence Microscopy - Mitosis, a phenomenon observed in all higher eukaryotes, is the mechanism that allows the nuclei of cells to split and provide each daughter cell with a complete set of chromosomes during cellular division. This, coupled with cytokinesis division of the cytoplasm , occurs in all multicellular plants and animals to permit growth of the organism.
Digital imaging with fluorescence microscopy is becoming a powerful tool to assist scientists in understanding the complex process of mitosis on both a structural and functional level. Mitosis Java Tutorial - Explore the stages of mitosis in eukaryotic cells with this interactive Java tutorial. Step through prophase, metaphase, anaphase, and telophase as the chromosomes slowly condense, align, and divide before being segregated into daughter cells. Cell Digestion and the Secretory Pathway - The primary sites of intracellular digestion are organelles known as the lysosomes, which are membrane-bounded compartments containing a variety of hydrolytic enzymes.
Lysosomes maintain an internal acidic environment through the use of a hydrogen ion pump in the lysosomal membrane that drives ions from the cytoplasm into the lumenal space of the organelles. The high internal acidity is necessary for the enzymes contained in lysosomes to exhibit their optimum activity.
Hence, if the integrity of a lysosomal membrane is compromised and the enzymatic contents are leaked into the cell, little damage is done due to the neutral pH of the cytoplasm.
If numerous lysosomes rupture simultaneously, however, the cumulative action of their enzymes can result in autodigestion and the death of the cell. License Info. Image Use. Custom Photos. Site Info. Contact Us. The Galleries:. Photo Gallery. Silicon Zoo. Chip Shots. DNA Gallery. Amino Acids. However, the mechanisms by which these viruses elicit immune responses and the determinants of their relative immunogenicity are incompletely understood.
Studying the interactions of VV and MVA with cells of the human immune system may elucidate these mechanisms, as well as provide a rational basis for the further enhancement of the immunogenicity of recombinant MVA vectors.
Toward this end, we investigated the consequences of MVA or VV infection of human dendritic cells DCs , key professional antigen-presenting cells essential for the generation of immune responses. Try out PMC Labs and tell us what you think. Learn More. Both pandemics are caused by RNA viruses and have reached us from animals. These two viruses are different in the transmission mode and in the symptoms they generate.
However, they have important similarities: the fear in the population, increase in proinflammatory cytokines that generate intestinal microbiota modifications or NETosis production by polymorphonuclear neutrophils, among others. They have been implicated in the clinical, prognostic and therapeutic attitudes.
In the last 50 years, we have experienced two pandemics, the human immunodeficiency virus HIV and the severe acute respiratory syndrome coronavirus 2 SARS-CoV-2 infections. Both are caused by natural viruses that have reached us from animals 1 - 3. Although these two viruses are different in the transmission mode and in the symptoms they generate, they have important similarities between them.
HIV infection was discovered in the 80s , when the first cases were known in young adults in California. It is believed that HIV spread to humans through direct contact with the infected blood of chimpanzees by hunting them for their meat. They were affected by severe pneumonia caused by Pneumocystis jiroveci or with Kaposi's sarcoma. The transmission mechanism was sexual contact, drugs injection, blood transfusions and mother-to-child.
A social stigma was generated. Since then, there has been a great advance in the knowledge of HIV, being one of the best-characterized known viruses, and a large amount of information has been accumulated about its biology, transmission and pathogenesis.
Although there is no cure for HIV infection, effective antiretroviral therapy ARTs can control the virus and help prevent transmission to other people.
The first news were released in January when the complete viral genome sequence was published 6 , showing that it was a new coronavirus belonging to the same group as the coronavirus related to the severe acute respiratory syndrome SARS-CoV causing the outbreak from SARS 7 - 9.
From that day on, most countries in the world have suffered the infection and it is not yet controlled. The data source was PubMed and the search terms and strategy were focused on the definition, epidemiology, transmission mechanism, symptomatology and finally treatment and vaccine development. The results are summarized in a narrative manner. HIV is a virus that belongs to the genus Lentivirus , subfamily Orthoretrovirinae , family Retroviridae. The HIV-1 virion is a spherical particle, with around nm of diameter, that contains two copies of single-stranded RNA together with the enzymatic machinery reverse transcriptase and integrase implicated in its transformation from RNA to DNA in the cytoplasm of the host cell and the subsequent integration of this material into the cell genome proviral DNA The HIV-1 envelope is formed by viral gp41 and gp envelope glycoproteins, with ability to bind to the CD4 surface protein, present in certain cells, including T lymphocytes and mononuclear phagocytic cells.
This union produces a conformational change in the viral glycoprotein that allows its subsequent interaction with one of the chemokine receptors CCR5 and CXCR4 , which act as co-receptors for the virus, allowing its entry into the cell. Once inside, it will use the enzyme reverse transcriptase to convert its RNA into DNA, which will be later transported to the nucleus and integrated into the cellular DNA.
Consequently, there is a depression of the immune system. If this depression becomes chronic, the patient progresses to AIDS There are estimations that predict 1. The results show that new infections of all ages decreased from a peak of 3. From the start of the pandemic until , 32 million people died from AIDS-related illnesses There are three transmission mechanisms of HIV-1 infection: sexual, parenteral and vertical HIV is found in blood, pre-seminal fluid, semen, vaginal fluids, and breast milk, and is transmitted through direct contact of these fluids with the mucosa or bloodstream of another person.
According to the data available, in Spain, the most frequent transmission mechanism nowadays is sexual, mainly from men who have sexual relations with other men approximately The symptoms generated by HIV infection begin to appear between 2 and 6 weeks after contact with the virus and can be divided into early infection within the first two months after infection or chronic.
During the early or acute phase of infection, infected people present fever, headache, muscle pain, rashes, sore throat and mouth sores, and swollen lymph nodes. These symptoms can be so mild that are almost not noticed 5. In the phase of chronic infection, the virus continues spreading and destroying immune cells, causing immunosuppression. When AIDS occurs, the immune system is already severely damaged, opportunistic infections, neurodegenerative diseases and cancers occur in infected individuals 5.
After the initial discovery of some drugs that had shown high toxicity and scarce benefit zidovudine, didanosine, zalcitabine , in the discovery of a combination therapy, which initially included antiprotease drugs indinavir, saquinavir was such a change that it was possible to significantly reduce mortality.
After , the emergence of new drugs, including integrase inhibitors, has led to significantly less toxicity and excellent tolerance However, HIV persists in the body due to the early establishment of reservoirs, which cannot be eliminated with any of the current antiretroviral regimens Reservoirs are defined as anatomical sites or cells in which HIV infection is persistent and stable allowing competent viruses to replicate under permissive conditions.
The rest of the virus genome encodes four essential structural proteins, namely spike glycoprotein S , small envelope E , matrix M and nucleocapside N Additional accessory proteins interfere with the immune response of the host. Zhou et al. This receptor is expressed in the lung, heart, blood vessels, intestine and kidneys The coronavirus membrane glycoprotein S is the one that binds to the ACE2 receptor on the surface of human cells The S glycoprotein has two subunits, namely S1 and S2 S1 determines the virus-host ratio and cell tropism with the key fusion domain, which is RBD, while S2 mediates the fusion of the virus cell membrane by two tandem domains: heptad repeats 1 HR1 22 and 2 HR2 After the fusion virus-cell occurs, the virus genome is released into the cytoplasm and the RNA translates two polyproteins, pp1a and pp1ab 24 , which encode non-structural proteins and form replication-transcription complexes RTCs in double-membrane vesicles RTCs replicate and synthesize sets of subgenomic RNAs 26 that encode for structural and accessory proteins.
By using cellular endoplasmic reticulum and the Golgi, newly formed RNAs, nucleocapsid proteins, and envelope proteins bind and form new viral particles Finally, the vesicles containing the virions fuse with the cell membrane and the virus goes out to infect new cells. The situation of SARS-CoV-2 infection today, November 7th , according to the WHO, is as follows: 48,, confirmed cases worldwide with 1,, deaths since the start of the pandemic in December Currently, the continent with most cases is America with 21,, confirmed cases and , deaths.
In Europe, the confirmed cases are 12,, with , deaths 4. These characteristics can explain the sudden pandemic spread of the virus The virus is transmitted through the air, mainly due to small drops of saliva from infected people by coughing or sneezing that can reach two meters The transmission is also produced by direct contact with these secretions or by objects contaminated by them 4.
The most common symptoms include fever, cough, and dyspnea. Diarrhea and abdominal pain are also frequent. Although most cases have mild symptoms, in the most severe cases, the infection can cause pneumonia, severe difficulty breathing, kidney failure, and even death 38 ,
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