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In low nitrogen environments, heterocyst differentiation is triggered by the transcriptional regulator NtcA. NtcA influences heterocyst differentiation by signaling proteins involved in the process of heterocyst differentiation. For instance, NtcA controls the expression of several genes including HetR which is crucial for heterocyst ...
In algae, akinetes form when environmental signals indicate impending change unfavorable to growth, such as the arrival of winter. Like cyanobacterial akinetes, they accumulate storage materials, but also develop thick cell walls and suspend active metabolism. [10] When conditions improve, the akinete germinates via the cell wall breaking open ...
By comparing the polymorphism within each species and the divergence observed between two species at two or more loci, the test can determine whether the observed difference is likely due to neutral evolution or rather due to adaptive evolution. [1] Developed in 1987, the HKA test is a precursor to the McDonald-Kreitman test, which was derived ...
Nostoc, also known as star jelly, troll's butter, spit of moon, fallen star, witch's butter (not to be confused with the fungi commonly known as witches' butter), and witch's jelly, is the most common genus of cyanobacteria found in a variety of both aquatic and terrestrial environments that may form colonies composed of filaments of moniliform cells in a gelatinous sheath of polysaccharides. [1]
After extraction, all specimen containers must be labeled with at least two of the following identifiers (at the time of collection): patient's name, date of birth, hospital number, test request form number, accession number, or a unique random number. All specimens should be labeled with the patient present.
The equivalent Mantoux test positive levels done with 10 TU (0.1 mL 100 TU/mL, 1:1000) are 0–4 mm induration (Heaf 0-1) 5–14 mm induration (Heaf 2) >15 mm induration (Heaf 3-4) The Mantoux test is preferred in the United States for the diagnosis of tuberculosis; multiple puncture tests, such as the Heaf test and Tine test, are not recommended.
The Hayflick limit, or Hayflick phenomenon, is the number of times a normal somatic, differentiated human cell population will divide before cell division stops. [ 1 ] [ 2 ] The concept of the Hayflick limit was advanced by American anatomist Leonard Hayflick in 1961, [ 3 ] at the Wistar Institute in Philadelphia , Pennsylvania.
Spherical colonies of radiating straight trichomes (filaments without sheaths). Each trichome has an akinete as the basal cell near the center of the colony. Akinetes if present are adjacent the heterocyst. The primary morphology is trichomous (filamentous without sheaths), the secondary is colonial. The mucilaginous sheath is top short at the ...