In eukaryotes the 40S and 60S ribosomal subunits are assembled in the nucleolus, but there appear to be mechanisms preventing mRNA binding, 80S formation, and initiation of translation in the nucleus. To visualize association between ribosomal subunits, we tagged pairs of Drosophila ribosomal proteins (RPs) located in different subunits with mutually complementing halves of fluorescent proteins. Pairs of tagged RPs expected to interact, or be adjacent in the 80S structure, showed strong fluorescence, while pairs that were not in close proximity did not. Moreover, the complementation signal is found in ribosomal fractions and it was enhanced by translation elongation inhibitors and reduced by initiation inhibitors. Our technique achieved 80S visualization both in cultured cells and in fly tissues in vivo. Notably, while the main 80S signal was in the cytoplasm, clear signals were also seen in the nucleolus and at other nuclear sites. Furthermore, we detected rapid puromycin incorporation in the nucleolus and at transcription sites, providing an independent indication of functional 80S in the nucleolus and 80S association with nascent transcripts.

The nucleolus is the most prominent morphological feature within the nucleus of eukaryotic cells and is best known for its role in ribosome biogenesis. It forms around highly transcribed ribosomal RNA gene repeats which yield precursor rRNAs that are co-transcriptionally processed, folded and, while still within the nucleolus, associate with most of the ribosomal proteins. The nucleolus is therefore often thought of as a factory for making ribosomal subunits, which are exported as inactive precursors to the cytoplasm where late maturation makes them capable of mRNA binding and translation initiation. However, recent studies have shown substantial evidence for the presence of functional, translation competent ribosomal subunits within the nucleus, particularly in the nucleolus. These observations raise the intriguing possibility that the nucleolus, as well as being a ribosome factory, is also an important nuclear protein-synthesis plant.

The distribution of assembled, and potentially translating, ribosomes within cells can be visualised in Drosophila by using Bimolecular Fluorescence Complementation (BiFC) to monitor the interaction between tagged pairs of 40S and 60S ribosomal proteins (RPs) that are close neighbours across inter-subunit junctions in the assembled 80S ribosome. Here we describe transgenes expressing two novel RP pairs tagged with Venus-based BiFC fragments that considerably increase the sensitivity of this technique we termed Ribo-BiFC. This improved method should provide a convenient way of monitoring the local distribution of ribosomes in most Drosophila cells and we suggest that it could be implemented in other organisms. We visualised 80S ribosomes in different neurons, particularly photoreceptors in the larva, pupa and adult brain. Assembled ribosomes are most abundant in the various neuronal cell bodies, but they are also present along the full length of axons. They are concentrated in growth cones of developing photoreceptors and are apparent at the terminals of mature larval photoreceptors targeting the larval optical neuropil. Surprisingly, there is relatively less puromycin incorporation in the distal portion of axons in the larval optic stalk, suggesting that some of the ribosomes that have initiated translation may not be engaged in elongation in growing axons. This article has an associated First Person interview with the first author of the paper.

8Rates of protein synthesis and the number of translating ribosomes vary greatly between 9 different cells in various cell states. The distribution of assembled, and potentially 10 translating, ribosomes within cells can be visualised in Drosophila by using Bimolecular 11Fluorescence Complementation (BiFC) to monitor the interaction between tagged pairs of 12 40S and 60S ribosomal proteins (RPs) that are close neighbours across inter-subunit 13 junctions in the assembled 80S ribosome. Here we describe transgenes that express two 14 novel RP pairs tagged with Venus-based BiFC fragments that considerably increase the 15 sensitivity of this technique that we termed Ribo-BiFC. This improved method should 16 provide a convenient way of monitoring the local distribution of ribosomes in most 17Drosophila cells and we suggest that could be implemented in other organisms. We 18 visualized 80S ribosomes in larval photoreceptors and in other neurons. Assembled 19 ribosomes are most abundant in the various neuronal cell bodies, but they are also present 20 along the lengths of axons and are concentrated in growth cones of larval and pupal 21 photoreceptors. Surprisingly, there is relatively less puromycin incorporation in the distal 22 portion of axons in the optic stalk, suggesting that some of the ribosomes that have 23 started translation may not be engaged in elongation in axons that are still growing. 24Running title: Ribosomes in axon growth cones 25

Aim: To determine the prevalence, pattern and risk factors of dating violence among undergraduate students of Usmanu Danfodiyo University Sokoto (UDUS). Methodology: It was a descriptive cross-sectional study involving 340 undergraduate students, selected via multistage sampling technique. A structured self-administered questionnaire was used to collect data from the respondents, and data were analyzed using IBM SPSS version 26.0 and Microsoft Excel 2016. Results: The ages of the respondents ranged from 18 to 29 years, with mean of 22.4±2 years; 218(66.9%) were males, 214(65.6%) were Hausa/Fulani and 266(81.9%) were Muslims. Majority of the respondents have been in a dating relationship for more than one academic year; 106(37.3%) of the dating partners were students of the university, of which 26(24.8%) were class mates. Current and lifetime prevalence of dating violence were 56% and 59.5% respectively. Form of dating violence experienced mostly by respondents was emotional/psychological violence [44(22.4%)], physical violence was the least experienced [27(14.04%)]. Up to 93(48%) of the dating violence took place on campus and 68(35%) of the perpetrators were current partners. Factors associated with dating violence included feeling overburdened by partners’ demands, and spending too much on partner. Conclusion: Current and lifetime prevalence of dating violence were high and emotional violence was the commonest form of dating violence experienced by respondents. There is need for school authorities to put in place mechanisms to identify victims of dating violence and come up with measures aimed at stemming the tide of dating violence in university campuses.