Hyaloid Vasculature and mmp2 Activity Play a Role during Optic Fissure Fusion in Zebrafish

Vertebrate retinal development requires timely and precise fusion of the optic fissure (OF). Failure of this event leads to congenital vision impairment in the form of coloboma. Recent studies have suggested hyaloid vasculature to be involved in OF fusion. In order to examine this link, we analyzed OF fusion and hyaloid vasculogenesis in the zebrafish pax2a noi mutant line. We first determined that pax2a−/− embryos fail to accumulate F-actin in the OF prior to basement membrane (BM) degradation. Furthermore, using 3D and live imaging we observed reduced OF hyaloid vascularization in pax2a−/− embryos. When examining the connection between pax2a loss of function and hyaloid vasculature, we observed significant reduction of talin1 expression, a regulator of hyaloid vasculature. In addition, cranial VEGF expression was found to be reduced in pax2a−/− embryos. Pharmacological inhibition of VEGF signaling phenocopied the pax2a−/− vasculature, F-actin and BM degradation phenotypes. Lastly, we determined that OF associated hyaloid vasculature is a source of mmp2, mmp14a and mmp14b expression and showed that mmp2 is functionally necessary for degradation of OF BM. Taken together we propose a pax2a driven mechanism that ensures proper and timely hyaloid vasculature invasion of the OF in order to facilitate availability of the BM remodeler mmp2

Spatiotemporal Characterization of Anterior Segment Mesenchyme Heterogeneity during Zebrafish Ocular Anterior Segment Development

Assembly of the ocular anterior segment (AS) is a critical event during development of the vertebrate visual system. Failure in this process leads to anterior segment dysgenesis (ASD), which is characterized by congenital blindness and predisposition to glaucoma. The anterior segment is largely formed via a neural crest-derived population, the Periocular Mesenchyme (POM). In this study, we aimed to characterize POM behaviors and transcriptional identities during early establishment of the zebrafish AS. Two-color fluorescent in situ hybridization suggested that early AS associated POM comprise of a heterogenous population. In vivo and time-course imaging analysis of POM distribution and migratory dynamics analyzed using transgenic zebrafish embryos (Tg[foxc1b:GFP], Tg[foxd3:GFP], Tg[pitx2:GFP], Tg[lmx1b.1:GFP], and Tg[sox10:GFP]) revealed unique AS distribution and migratory behavior among the reporter lines. Based on fixed timepoint and real-time analysis of POM cell behavior a comprehensive model for colonization of the zebrafish AS was assembled. Furthermore, we generated single cell transcriptomic profiles (scRNA) from our POM reporter lines and characterized unique subpopulation expression patterns. Based on scRNA clustering analysis we observed cluster overlap between neural crest associated (sox10/foxd3), POM (pitx2) and finally AS specified cells (lmx1b, and foxc1b). scRNA clustering also revealed several novel markers potentially associated with AS development and/or function including lum, fmoda, adcyap1b, tgfbi, and hmng2. Taken together, our data indicates that AS-associated POM, or Anterior Segment Mesenchyme (ASM), is not homogeneous but rather comprised of several subpopulations with differing colonization patterns, migration behavior, and transcriptomic profiles

Improvement of water use efficiency in pomegranate (Punica granatum) cv. Bhagwa under micro-irrigation system

A field experiment was conducted to evaluate the effect of different irrigation levels (10 to 50 and 20 to 60%) and mulches (No mulch, dry lawn mulch, dry lawn mulch + hydrogel and hydrogel alone) on growth and yield of Bhagwa pomegranate (Punica granatum L.). The actual pomegranate evapotranspiration in l/day/tree was estimated by using the reference crop evapotranspiration, pan coefficient, crop coefficient, wetted area, area occupied by one tree and micro-irrigation efficiency. The study revealed that mulch + hydrogel enhanced vegetative growth and yield contributing characteristics. However, 30 and 40% irrigation levels for three and four years pomegranate plants, respectively, produced results at par with respect to yield attributing traits, quality, juice content and TSS. Based on statistical analysis of vegetative and yield characteristics, it was inferred that the treatment combination comprising of dry lawn mulch + hydrogel and irrigation levels at 30 and 40% with alternate day irrigation resulted into higher yield with good quality fruits as compared to other treatments

Morphological measurements, length weight relationship and relative condition factor (Kn) of Obtuse barracuda Sphyraena obtusata (Cuvier, 1829) from South-eastern Arabian Sea

The study investigated morphometric and meristic measurements, length-weight relationship (LWR) and relative condition factor (Kn) of the Sphyraena obtusata from south-eastern Arabian Sea from August 2019 to March 2020. Three hundred and fifty two specimens having a length and weight range of 16.5 – 30.1 cm and 29.54 – 155.20 g, respectively were analyzed for morphological measurements (13 morphometric and 11 meristic), LWR and relative condition factor. The maximum correlation were existed between standard length (r > 0.985), fork length (r > 0.979) and pre-dorsal length 1 (r > 0.942) among the various morphometric variables. A disparity in relative growth was noticed among the morphometric traits. The Regression coefficient b value clearly indicates that growth of all the morphometric characters were isometric in connection with the total length, except for pelvic length (negative allometric), body depth (positive allometric) and caudal depth (positive allometric) (p < 0.01). The length-weight relationship of the individual sexes (male, female) and pooled data is indicated as W = 0.02275 L2.6033, W = 0.01786 L2.6815 and W = 0.01945 L2.6541 having the value of coefficient of determination (r2) as 0.9566, 0.9696 and 0.9658, respectively. The ‘b’ values for both males and females divulge negative allometric growth (p < 0.05). There was no significant difference for the relative condition factor (Kn) among the months and size groups.

Morphological measurements, length weight relationship and relative condition factor (Kn) of Obtuse barracuda Sphyraena obtusata (Cuvier, 1829) from South-eastern Arabian Sea

The study investigated morphometric and meristic measurements, length-weight relationship (LWR) and relative condition factor (Kn) of the Sphyraena obtusata from south-eastern Arabian Sea from August 2019 to March 2020. Three hundred and fifty two specimens having a length and weight range of 16.5 – 30.1 cm and 29.54 – 155.20 g, respectively were analyzed for morphological measurements (13 morphometric and 11 meristic), LWR and relative condition factor. The maximum correlation were existed between standard length (r > 0.985), fork length (r > 0.979) and pre-dorsal length 1 (r > 0.942) among the various morphometric variables. A disparity in relative growth was noticed among the morphometric traits. The Regression coefficient b value clearly indicates that growth of all the morphometric characters were isometric in connection with the total length, except for pelvic length (negative allometric), body depth (positive allometric) and caudal depth (positive allometric) (p < 0.01). The length-weight relationship of the individual sexes (male, female) and pooled data is indicated as W = 0.02275 L2.6033, W = 0.01786 L2.6815 and W = 0.01945 L2.6541 having the value of coefficient of determination (r2) as 0.9566, 0.9696 and 0.9658, respectively. The ‘b’ values for both males and females divulge negative allometric growth (p < 0.05). There was no significant difference for the relative condition factor (Kn) among the months and size groups

Morphometry, length-weight relationship and relative condition factor of red-toothed trigger fish, Odonus niger

Aim: The study aimed to investigate the morphometric and meristic measurements, length-weight relationship and relative condition factor of Odonus niger landed along coastal Karnataka. Methodology: The morphometric and meristic measurements, length-weight relationship and relative condition factor (Kn) of O. niger was studied for a period of eight months from August 2019 to March 2020. The different morphometric characters were subjected to statistical analysis. The length-weight relationship was analyzed for both the sexes (female and male) and combined data. Monthly relative condition factor was analyzed for both the sexes and for different size group. Results: A comparison of different morphometric measurements exhibited good extent of correlation indicating good extent of interdependence of these characters. Four out of eight morphometric characters are environmentally controlled and suggested wide range of zoogeographical distribution of O. niger. The length-weight relationship is indicated as W = 0.046 L2.565, W = 0.044 L2.589 and W = 0.047 L2.561 with coefficient of determination (r2) of 0.910, 0.913 and 0.910 for male, female and combined sexes, respectively. The 'b' values of both the sexes (male and female) exhibited negative allometric growth (p<0.05) and appeared to be leaner. There was no significant (p<0.05) variation for relative condition factor (Kn) among the months and size groups. However, little higher values were observed during November and February. Interpretation: The study fills the knowledge gap and support for developing a suitable management system for this fish species