Overview

Brief Summary

Introduction

Jakoba is a group of jakobid flagellates. At present there is a single described species, Jakoba libera (Ruinen, 1938) Patterson, 1990.

Jakoba incarcerata described by Bernard et al. 2000 has now been renamed Andalucia incarcerata (Lara et al., 2006), while 'Jakoba bahamensis' / 'Jakoba bahamiensis' is not formally described. In fact, molecular phylogenies indicate that neither are specifically related to Jakoba libera (Simpson et al., 2002; Lara et al., 2006; Rodriguez-Ezpeleta, 2007; Simpson et al., 2008; Hampl et al. unpublished).

There are two cultures identified as Jakoba libera for which small subunit ribosomal RNA gene sequences are available - ATCC 50422 and WHOI DB9. The sequences are 95% identical, and are always recovered as a clade relative to other jakobids (Cavalier-Smith, 2003; Lara et al., 2006). The Jakoba libera morphospecies, so far, therefore, appears to be a clade.

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Comprehensive Description

Characteristics

Jakoba libera is a bacterivorous flagellate with two flagella. It is free-swimming, but often attaches to surfaces by the anterior flagellum during feeding. As in other jakobids, and many other excavates, the posterior flagellum beats within a broad ventral groove. The current generated by the flagellum draws suspended prokaryotes into the groove, where they are phagocytosed.

Jakoba libera has been reported from marine samples, and from hypersaline sites (Patterson, 1990; Ruinen, 1938).

The mitochondrial genome of Jakoba libera, while still remarkably gene-rich, includes fewer genes than other jakobid mitochondrial genomes studied to date (Gray et al., 2004). For example, only two subunits of eubacterial-type RNA polymerase are encoded by the mitochondrial genome, whereas other jakobids (e.g. Reclinomonas americana) have four mitochondrially-encoded subunits.

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Description of Jakoba libera

The organism is a biflagellated protist with an acutely obovate cell body measuring 6-9.5 microns long, with most cells 7-8 microns in length. The anterior flagellum is inserted apically. It measures about one and a half times the length of the body and is held in a hook shape. The posterior flagellum is inserted slightly subapically, is about the same length as the anterior flagellum and lies in a ventral groove of the body. Normally it beats actively. Both flagella are acronematic. The cells may swim but usually adhere to debris with the crook of the anterior flagellum. They may deform and squirm when compressed in debris. During feeding, the posterior flagellum creates a current of water from which bacteria are removed. Bacteria are collected in the groove, ingested, and the resulting food vacuoles are found mostly in the posterior part of the cell.
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Source: BioPedia

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Ecology

Habitat

Depth range based on 1 specimen in 1 taxon.

Environmental ranges
  Depth range (m): 0.75 - 0.75
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.
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Depth range based on 1 specimen in 1 taxon.

Environmental ranges
  Depth range (m): 0.75 - 0.75
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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