Swimming as Individuals Sample Clauses

Swimming as Individuals. Flagella drive translocation of individual cells through aqueous environments or within semi-liquid substrates, called swimming (105). Swimmer cells can be likened to pioneers in search of a more favorable environment mediated by chemotaxis. There are different patterns of flagellation in prokaryotes: including a single, polar flagellum (monotrichous), several flagella at one pole (lophotrichous), flagella at both poles (amphitrichous), or flagella distributed along the cell surface (peritrichous). Different patterns of flagellation, cell shape, swimming velocity, and mechanisms of running/tumbling affect the three-dimensional manner bacteria swim and tolerate viscous environments. Gram-negative enteric bacteria (E. coli, S. enterica, and P. mirabilis) are peritrichously flagellated when swimming. E. coli and S. enterica typically have 6-8 flagellar filaments while P. mirabilis has 4-10. The hook of each flagellar filament is flexible and permits rotation up to angles of 90°. Flexibility of the hook is essential for normal swimming, as artificially stiffening it impedes swimming motility (172). Each flagellar filament spends the majority of the time (95%) rotating CCW, forcing them to form a bundle which propels these bacteria through the environment. The switch of individual filaments to CW rotation in response to environmental changes forces the bundle apart and results in tumbling. Each flagellum has its own switching frequency and the rate of tumbling is dependent on the number of flagella that change rotation at any time (173, 174). E. coli and S. enterica swim at speeds between 15 μm/s and 30 μm/s (175, 176). P. mirabilis swims at a rate of 25 μm/s but low pH and high salinity reduce swimming speeds (92). E. coli and S. enterica are model organisms for the study of flagellar assembly and chemotaxis. However, the mechanisms employed by these bacteria to exploit their respective niches are not shared by other bacteria. Examples of swimming behavior in non-enteric bacteria are discussed below. The photosynthetic bacterium Rhodobacter sphaeroides has a single, polar flagellum that only rotates CW. This bacterium does not exhibit the “run and tumble” behavior seen in enteric bacteria. Rather, R. sphaeroides changes direction by stopping and starting flagellar rotation. Starvation for a specific metabolite causes R. sphaeroides to increase its speed from 5 µm/s to 50 µm/s, and when chemotactically stimulated, only a subset of cells respond to the gradient ...
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Related to Swimming as Individuals

  • Permanent Part-Time Employees (1) Pay and benefits will be computed on a prorated monthly or pay period basis, such as one-half (½) monthly or pay period pay for a half-time employee, or pay will be computed on an hourly basis, and pay and benefits will be normally prorated on a pay period, pay status basis. Permanent part-time employees in permanent full-time positions will be treated as permanent part-time for purposes of this Article.

  • Laid Off Employees A) Should vacancies occur following layoff, those employees on layoff will be recalled to these positions in order of seniority providing they have the capabilities and the qualifications to perform the duties of the vacant position. If no employee on layoff possesses the required capabilities and qualifications, the vacant position will be posted pursuant to Article 15.01.

  • Term Employees (a) On termination, a term employee, with or without dependants, who leases unfurnished accommodations, or who leases furnished accommodations or owns his/her own home, will be provided financial assistance on a percentage basis for years of completed service, as defined in Table A-6.

  • Project Employees Project employees who have not held permanent civil service status within the job classification, will not volunteer for or be assigned overtime work outside of the project. Required overtime within a project may first be assigned to qualified employees within the project by seniority. The process for assigning the overtime will follow the procedures outlined in this Article.

  • Sick Leave Days Payable at 100% Wages Permanent Employees Subject to paragraphs d), e) and f) below, Employees will be allocated eleven (11) sick days payable at one hundred percent (100%) of wages on the first day of each fiscal year, or the first day of employment.

  • Key Individuals 20.1. The Contractor acknowledges that the Key Individuals are essential to the proper provision of the Services to the Authority.

  • Food Service Employees School year food service employees shall be entitled to the following paid vacation schedule:

  • Current Employees Employees who are eligible to participate but not deferring shall have Elective Deferrals withheld in the amount of ______ % of Compensation or $_________ of Compensation. Employees and Participants shall have the right to amend the stated automatic Elective Deferral percentage or receive cash in lieu of deferral into the Plan.

  • Permanent Full-Time Employees Pay and benefits will be computed on a monthly pay status basis.

  • Fixed Term Employees 31. The only terms of this Agreement that apply to employees who are not regular employees are those that are set out in Articles 31A, 32, 33 and 34. ARTICLE 31A – FIXED-TERM EMPLOYEES OTHER THAN SEASONAL, STUDENT AND GO TEMP EMPLOYEES (FXT) 31A.1 Articles 31A.2 to 31A.16 apply only to fixed-term employees other than seasonal, student and GO Temp employees.

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