WormMine: ExpressionPattern Expr11974

• Pattern: Expression of INX-8, -9, -14, -21 and -22 overlapped closely throughout the gonad in wild-type adult hermaphrodites. In distal arms clusters of fine puncta were associated with each germ cell, as previously reported for INX-14 and INX-22 expression (Govindan et al. 2009). INX-8/9 (antibodies raised against INX-8 shown to cross-react with INX-9) INX-8::GFP and INX-9::GFP were expressed in the distal tip cell (DTC) in addition to the somatic sheath. In the DTC, INX-8/9, INX-8::GFP and INX-9::GFP associated with long processes that extended from the DTC proximally, especially those running between germ cells and intercalating among them. At the distal limit of sheath cell coverage of germ cells, longer formations sometimes appeared associated with the apparent edge of the sheath cells. At the loop region of the gonad arm, individual puncta appeared in larger, higher-density aggregates. In the proximal arm puncta size was more variable, with many appearing to be considerably larger than the fine puncta seen in the distal arm. The expression levels of INX-8, INX-9 appeared higher in the proximal gonad. Throughout the gonad the localization patterns of INX-8::GFP and INX-9::GFP were indistinguishable. In addition to gonadal expression, antibody staining of whole mounts suggested that INX-8/9 may be expressed in some pharyngeal and a few other head neurons (T. Starich, unpublished results), but because the antibody reacted primarily with processes and not cell bodies we did not attempt to identify these neurons. Male gonads were examined and found to express INX-8, -9, -14, -21 and -22 as well. Presumptive gap junctions forming between both male distal tip cells and germ cells were detected with antibodies specific to INX-8/9, INX-14, INX-21, and INX-22. INX-8::GFP and INX-9::GFP were both expressed in the DTCs. No expression was detected in the transition zone, but innexin expression appeared to outline individual germ cells in the pachytene region. All 5 innexins are also expressed in the regions occupied by differentiated spermatocytes and sperm, with evidence of puncta formation. Expression of INX-9::GFP visualized somatic coverage of spermatids, probably by cells of the seminal vesicle, but somatic coverage of germ cells in the pachytene region of the male gonad has not been described. Examination of earlier developmental stages showed that all five innexins are expressed in the primordial gonad, consisting of somatic gonadal precursors Z1 and Z4 and the primordial germ cells Z2 and Z3. Early larval expression patterns differ from adults in that distinct, well-defined puncta potentially corresponding to gap junctions are less clearly discernible. In L2-L4 larval stages, germ cell innexins appear to be continually expressed, and somatic innexins are expressed predominantly in the DTC. In late L2 and early L3 stages, as the gonad arm lengthens, the migrating DTC seems to trail a process behind it that maintains contact with the germ cell compartment. The DTC appears to form gap junctions with germ cells at both long external processes and processes that intercalate between germ cells. At this time a second, more proximal focus of somatic innexin expression was sometimes detected. Though this second focus might represent extensions from the DTC, expression of inx-9::gfp suggested that other somatic cells besides the DTC might be involved. By the late L3 stage, the DTC no longer appears to be in contact with all of the germ cells. To better understand the contacts between germ cells and the DTC, we examined early L4-stage animals by TEM. We observed several processes trailing behind the DTC cell body on the outer edge of the germ line, as well as extensions that dig deeply between germ cells. The immunofluorescence results suggest that gap junctions form between the DTC and germ cells at both the outer and inner DTC arms. The inx-8 promoter was fused to mCherry, and inx-8p::mCherry was expressed during larval development in most or all of the somatic gonad cells derived from Z1 and Z4, including the DTC, sheath/spermathecal precursors and uterine cell precursors. We conclude that although expression of INX-8/9 appears to be strongest in the DTC during larval development, other somatic gonad cells may also express INX-8/9 at this time.
• Primary Identifier: Expr11974

11 Anatomy Terms

Definition	Name	Synonym	Primary Identifier
somatic cell that situates at the tip of a gonad arm.	distal tip cell	DTC	WBbt:0006865
neuron with its cell body situated in the head, excluding the pharynx.	head neuron		WBbt:0006751
neuron of the pharyngeal nervous system.	pharyngeal neuron		WBbt:0005439
five pairs of thin gonadal sheath cells form a single layer covering the germ line component of each arm, each pair occupying a stereotyped position along the gonad proximal-distal axis.	gonadal sheath cell		WBbt:0005828
Male haploid germ cell.	sperm	spermatozoa	WBbt:0006798
organ producing either sperm or ova.	gonad		WBbt:0005175
A cell which gives rise to spermatids by meiosis.	spermatocyte		WBbt:0006799
Somatic gonad precursor cell	Z4	lineage name: MSappaap	WBbt:0004574
Somatic gonad precursor cell	Z1	lineage name: MSpppaap	WBbt:0004577
Germ line precursor cell	Z2	lineage name: P4.p	WBbt:0004576
Germ line precursor cell	Z3	lineage name: P4.a	WBbt:0004575

2 Genes

WormBase Gene ID	Gene Name	Sequence Name	Organism
WBGene00002130	inx-8	ZK792.2	Caenorhabditis elegans
WBGene00002131	inx-9	ZK792.3	Caenorhabditis elegans

1 Life Stages

Remark	Definition	Other Name	Public Name	Primary Identifier
	All C. elegans development stages, including embryo, larva and adult stage.		all stages Ce	WBls:0000002