Can Probiotics Affect Reproductive Processes of Aquatic Animals? - Aquaculture Nutrition: Gut Health, Probiotics and Prebiotics - page 340

In fact, by investigating zebrafish preovulatory follicles (stages III and IV) by electron
microscopy, an increased number of autophagosomes were observed in follicles from females
fed the probiotic. This was confirmed by increased expression of genes involved in the
autophagic process (such as ambra1, becn1, lc3 and uvrag), by increased LC3-II protein levels
and by decreased p62 protein levels in preovulatory follicles from females fed the probiotic.
Concomitantly a decrease in the apoptotic process in the ovary was indicated from TUNEL
assays and confirmed by lower expression of genes involved in apoptosis (i.e. p53, bax, apaf
and cas3) and higher expression of igfII and igf1r (Gioacchini et al. 2013). During teleost
vitellogenesis, apoptosis controls the number of developing oocytes, whereas autophagy
provides a source of energy from those oocytes that fail to develop properly (Wood and Van
Der Kraak 2003; Santos et al . 2008), and therefore the findings following administration of
Lb. rhamnosus (Gioacchini et al. 2013) may infer an elevated efficacy for energy recycling in
highly active ovaries to produce an elevated number of mature oocytes and eggs.

12.5.3 Probiotic effects on killifish reproduction
The results obtained by Lombardo and co-workers (2011) represent the only data currently
available on the effects of probiotics on the reproduction of marine fish species at this time.
These authors administered dietary Lb. rhamnosus at 10 6 CFU g -1 to killifish, a euryhaline
oviparous teleost that in nature displays semi-lunar spawning cycles synchronized with new
and full moon tides (Taylor 1986). Due to its appropriate size and its capacity for successful
reproduction under laboratory conditions, this species can be utilized as an excellent fish
model for research studying the endocrine control of reproductive cycles in marine teleosts
(Shimizu 2003).
After 10 days administration of Lb. rhamnosus to killifish breeders, a significantly higher
fecundity, in terms of mean numbers of eggs spawned (twofold increase) and a higher GSI
(+15%), was observed in females fed the probiotic supplemented diet when compared with
females fed the control diet. The hatching rate of killifish occurred at 8 days post fertilization
(dpf), which was not affected by Lb. rhamnosus administration, but the embryo survival rate
at 8 dpf was significantly enhanced by probiotic treatment (Table 12.2). From 10 days post
hatching (dph) larvae hatched from the probiotic group showed a significantly higher total
length (TL) with respect to the control larvae and the differences remained significant until
the end of the experiment (30 dph); indeed, the TL of larvae hatched from the probiotic fed
group at 20 dph was the same as the TL of larvae hatched from the control group at 30 dph.
Differences in body weight (BW) were significant only at 30 dph. Larval survivorship was not
affected by probiotic treatment.

Table 12.2 Reproductive performance of control and probiotic fed groups of
Fundulus heteroclitus. Mean values per female ± standard deviation. Different
superscript letters indicate statistically significant differences ( P 0.05).

<

Control Lb. rhamnosus

8.0 ± 1.2 a 15.0 ± 1.5 b Gonadosomatic index (%)

107.9 ± 36.1 a 204.3 ± 49.2 b Fecundity (number of eggs spawned per day)

92.8 ± 28.0 a 181.9 ± 47.7 b Embryo survival (at 8 dph)

75.7 ± 10.8 a 79.2 ± 6.6 b

Hatching rate (%)

Source: Lombardo et al . 2011.