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Auxiliary Cell

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auxiliary cell

Few species in the genus Grateloupia have been investigated in detail with respect to the development of the auxiliary cell ampullae before or after diploidization. In this study, we document the vegetative and reproductive structures of two new species of Grateloupia, G. taiwanensis S.-M. Lin et H.-Y. Liang sp. nov. and G. orientalis S.-M. Lin et H.-Y. Liang sp. nov., plus a third species, G. ramosissima Okamura, from Taiwan. Two distinct patterns are reported for the development of the auxiliary cell ampullae: (1) ampullae consisting of three orders of unbranched filaments that branch after diploidization of the auxiliary cell and form a pericarp together with the surrounding secondary medullary filaments (G. taiwanensis type), and (2) ampullae composed of only two orders of unbranched filaments in which only a few cells are incorporated into a basal fusion cell after diploization of the auxiliary cell and the pericarp consists almost entirely of secondary medullary filaments (G. orientalis type). G. orientalis is positioned in a large clade based on rbcL gene sequence analysis that includes the type species of Grateloupia C. Agardh 1822, G. filicina. G. taiwanensis clusters with a clade that includes the generitype of Phyllymenia J. Agardh 1848, Ph. belangeri from South Africa; that of Prionitis J. Agardh 1851, Pr. lanceolata from Pacific North America; and that of Pachymeniopsis Y. Yamada ex Kawab. 1954, Pa. lanceolata from Japan. A reexamination of the type species of the genera Grateloupia, Phyllymenia, Prionitis, and Pachymeniopsis is required to clarify the generic and interspecific relationships among the species presently placed in Grateloupia.

Like all-electric vehicles, fuel cell electric vehicles (FCEVs) use electricity to power an electric motor. In contrast to other electric vehicles, FCEVs produce electricity using a fuel cell powered by hydrogen, rather than drawing electricity from only a battery. During the vehicle design process, the vehicle manufacturer defines the power of the vehicle by the size of the electric motor(s) that receives electric power from the appropriately sized fuel cell and battery combination. Although automakers could design an FCEV with plug-in capabilities to charge the battery, most FCEVs today use the battery for recapturing braking energy, providing extra power during short acceleration events, and to smooth out the power delivered from the fuel cell with the option to idle or turn off the fuel cell during low power needs. The amount of energy stored onboard is determined by the size of the hydrogen fuel tank. This is different from an all-electric vehicle, where the amount of power and energy available are both closely related to the battery's size. Learn more about fuel cell electric vehicles.

Previously, we showed that chitin synthase 2 (Chs2) is required for septum formation in Saccharomyces cerevisiae, whereas chitin synthase 1 (Chs1) does not appear to be an essential enzyme. However, in strains carrying a disrupted CHS1 gene, frequent lysis of buds is observed. Lysis occurs after nuclear separation and appears to result from damage to the cell wall, as indicated by osmotic stabilization and by a approximately 50-nm orifice at the center of the birth scar. Lysis occurs at a low pH and is prevented by buffering the medium above pH 5. A likely candidate for the lytic system is a previously described chitinase that is probably involved in cell separation. The chitinase has a very acidic pH optimum and a location in the periplasmic space that exposes it to external pH. Accordingly, allosamidin, a specific chitinase inhibitor, substantially reduced the number of lysed cells. Because the presence of Chs1 in the cell abolishes lysis, it is concluded that damage to the cell wall is caused by excessive chitinase activity at acidic pH, which can normally be repaired through chitin synthesis by Chs1. The latter emerges as an auxiliary or emergency enzyme. Other experiments suggest that both Chs1 and Chs2 collaborate in the repair synthesis of chitin, whereas Chs1 cannot substitute for Chs2 in septum formation.

A general protocol for labeling of fixed and permeabilized cells containing metabolically functionalized Alkyne- or Azide-modified biomolecules is outlined below (see 3.) however, individual optimization might be required for different CUAAC labeling experiments as well as for critical reaction parameter e.g. final CuSO4 concentration, CuSO4:BTTAA ratio, detection reagent concentration.

Please note: The fixation with 3.7% formaldehyde in PBS and subsequent permeabilization with 0.5% Triton X-100 is a general guideline. Optimization might be required. Different reagent concentrations, different fixation and permeabilization reagents (e.g. methanol or saponin) or TBS as buffer solution intstead of PBS can be used as well. Permeabilization is not required for cell surface or lipid component labeling.

Please note: Both the final CuSO4 concentration as well as CuSO4:BTTAA ratio are critical parameters for CuAAC reaction efficiency. A final CuSO4 concentration of 2 mM and a CuSO4:BTTAA ratio of 1:5 is recommended as a starting point for labeling of fixed and permeabilized cells containing metabolically Azide- or Alkyne-functionalized biomolecules. Individual optimization for each assay is strongly recommended. Minimum CuSO4 concentration: 50 μM.

Queen production in stingless bees with fusion of neighboring brood cells occurs by the perforation of the adjacent brood cell or construction of an auxiliary one. This study describes the auxiliary brood cell building behavior in queenless colonies of Plebeia lucii. Queenright and queenless (orphan) colonies were monitored, and auxiliary cell construction was video-recorded in orphan colonies. Brood cells with auxiliary cells added were analyzed with X-rays to identify the amount of food and the larval behavior into the brood cells. Plebeia lucii had specific behavioral sequence in auxiliary cell building. The addition of auxiliary cells is the main strategy to produce queens in P. lucii, mainly for the production of emergency queens in orphan colonies because queen absence triggered a high production of auxiliary cells. X-ray analyses showed that auxiliary cell addition occurred when the food in the larval brood cells had been completely eaten and showed changes in dorsoventral position of the larvae. Larvae of males did not perforate auxiliary cells, indicating that sex-related factors affect this behavior. The wax handling by workers and the fused thin and concave-shaped wall between the auxiliary and larval brood cells seems to facilitate wall perforation by the larvae.

Stingless bees (Apidae: Meliponini) produce gynes throughout the year to replace the physogastric one and for swarming, but some of them may be killed by workers or remain caged in wax prisons (Imperatriz-Fonseca and Zucchi 1995; Ribeiro et al. 2003, 2006). Two queen production methods occur in Meliponini (Hartfelder et al. 2006): (i) queens and workers emerge from brood cells with similar sizes and caste determination occurs due to genetic and food quality differences (Engels and Imperatriz-Fonseca 1990; Jarau et al. 2010; Schwander et al. 2010) and (ii) larvae growing in brood cells with high food provision will become queens. The second mechanism occurs in species that build queen brood cells larger than those for workers, or when the larvae, after feeding on its provision, perforate a contiguous brood cell and consume additional available food (Engels and Imperatriz-Fonseca 1990; Hartfelder et al. 2006).

Plebeia lucii Moure (Apidae: Meliponini) is c.a. 3.0 mm long, and its brood cells are cluster-shaped (Moure 2004). Queen production in this specie by auxiliary cell addition was recorded in a previous study (Teixeira 2007). The objective of the present study was to describe for the first time the worker behavior in the construction of auxiliary cells for queen production in P. lucii.

After the first phase of observations, brood cells with pupae were removed from the colonies and kept in Petri dishes at 24 to 28 C. The emerged adult bees were labeled with non-toxic paint on the thorax to know how old the bees that build auxiliary cells are. Multiple age cohorts were color-marked per colony. The labeled bees were returned to their original colonies after queen removal (beginning of the second phase of observation).

Queens were removed, and each queenless colony was monitored for 8 h/day for 50 days. Cell construction and worker oviposition were video-recorded. The removed physogastric queens were transferred to cages with workers of the same colony, from where new brood cells were produced and transferred to orphaned colonies without brood cells for possible addition of auxiliary cells.

Brood cells with auxiliary cells added were submitted to LX-60 X-rays and photographed with a digital camera (Faxitron X-ray Corp., Wheeling, IL) to identify the larva position in relation to the auxiliary cell construction site, the amount of food in the brood cell, and the larval behavior in brood cells with auxiliaries annexed.

Definitions, characterizations, and terminologies had not been made in previous work to the auxiliary cell building process. Here, we present a proposal to report this behavior in P. lucii using the provisioning and oviposition process (POP) descriptions in other stingless bee species.

The video-record monitoring of the queenright colonies of P. lucii showed only the quiescent phase and provisioning and oviposition processes (POP) of brood cells. Auxiliary cells were produced, but their building processes were not reported because they were found completely constructed. Five queenright colonies had two auxiliary cells per completely built brood cell, which hampered observation of worker behavior during construction of the auxiliary cells. Queen brood cells were not found. 041b061a72


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